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A-59

INSTRUCTION SET REFERENCE

Operation:

DJNZ
(PC)

←

(PC) + 2

(Rn)

←

(Rn) – 1

IF (Rn) > 0 or (Rn) < 0
THEN
(PC)

←

(PC) + rel

ECALL <dest>

Function:

Extended call

Description:

Calls a subroutine located at the specified address. The instruction adds four to the program
counter to generate the address of the next instruction and then pushes the 24-bit result
onto the stack (high byte first), incrementing the stack pointer by three. The 8 bits of the high
word and the 16 bits of the low word of the PC are then loaded, respectively, with the
second, third and fourth bytes of the ECALL instruction. Program execution continues with
the instruction at this address. The subroutine may therefore begin anywhere in the full 16-
Mbyte memory space.

Flags:

Example:

The stack pointer contains 07H and the label “SUBRTN” is assigned to program memory
location 123456H. After executing the instruction

ECALL SUBRTN

at location 012345H, SP contains 0AH; on-chip RAM locations 08H, 09H and 0AH contain
01H, 23H and

45H,

respectively; and the PC contains 123456H.

Variations

ECALL addr24

Binary Mode

Source Mode

Bytes:

5

4

States:

14

13

Hex Code in:

Binary Mode = [A5][Encoding]
Source Mode = [Encoding]

Operation:

ECALL
(PC)

←

(PC) + 4

(SP)

←

(SP) + 1

((SP))

←

(PC.23:16)

(SP)

←

(SP) + 1

((SP))

←

(PC.15:8)

(SP)

←

(SP) + 1

((SP))

←

(PC.7:0)

(PC)

←

(addr.23:0)

CY

AC

OV

N

Z

—

—

—

—

—

[Encoding]

1 0 0 1

1 0 1 0

addr23–

addr16

addr15–addr8

addr7–addr0

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Содержание 8XC251SA

Страница 1: ...8XC251SA 8XC251SB 8XC251SP 8XC251SQ Embedded Microcontroller User s Manual 8XC251SA 8XC251SB 8XC251SP 8XC251SQ Embedded Microcontroller User s Manual 27279502 qxd 6 18 96 9 25 AM Page 1...

Страница 2: ......

Страница 3: ...May 1996 8XC251SA 8XC251SB 8XC251SP 8XC251SQ Embedded Microcontroller User s Manual...

Страница 4: ...ut notice Microcontroller products may have minor variations to this specification known as errata Other brands and names are the property of their respective owners Contact your local Intel sales off...

Страница 5: ...chip Code Memory 2 7 2 2 5 On chip RAM 2 7 2 3 ON CHIP PERIPHERALS 2 7 2 3 1 Timer Counters and Watchdog Timer 2 7 2 3 2 Programmable Counter Array PCA 2 8 2 3 3 Serial I O Port 2 8 CHAPTER 3 ADDRESS...

Страница 6: ...12 4 5 3 1 Configuration Bits WSA1 0 WSB1 4 12 4 5 3 2 Configuration Bit WSB 4 12 4 5 3 3 Configuration Bit XALE 4 13 4 6 OPCODE CONFIGURATIONS SRC 4 13 4 6 1 Selecting Binary Mode or Source Mode 4 1...

Страница 7: ...INTERRUPT PRIORITIES 6 7 6 7 INTERRUPT PROCESSING 6 9 6 7 1 Minimum Fixed Interrupt Time 6 10 6 7 2 Variable Interrupt Parameters 6 10 6 7 2 1 Response Time Variables 6 10 6 7 2 2 Computation of Wors...

Страница 8: ...e 8 11 8 6 2 Auto reload Mode 8 12 8 6 2 1 Up Counter Operation 8 12 8 6 2 2 Up Down Counter Operation 8 13 8 6 3 Baud Rate Generator Mode 8 14 8 6 4 Clock out Mode 8 14 8 7 WATCHDOG TIMER 8 16 8 7 1...

Страница 9: ...0 6 3 1 Timer 1 Generated Baud Rates Modes 1 and 3 10 11 10 6 3 2 Selecting Timer 1 as the Baud Rate Generator 10 11 10 6 3 3 Timer 2 Generated Baud Rates Modes 1 and 3 10 12 10 6 3 4 Selecting Timer...

Страница 10: ...13 5 1 Real time WAIT Enable RTWE 13 12 13 5 2 Real time WAIT CLOCK Enable RTWCE 13 12 13 5 3 Real time Wait State Bus Cycle Diagrams 13 12 13 6 CONFIGURATION BYTE BUS CYCLES 13 15 13 7 PORT 0 AND POR...

Страница 11: ...NS 14 6 14 6 1 On chip Code Memory 14 7 14 6 2 Configuration Bytes 14 7 14 6 3 Lock Bit System 14 7 14 6 4 Encryption Array 14 8 14 6 5 Signature Bytes 14 8 14 7 VERIFYING THE 83C251SA SB SP SQ ROM 14...

Страница 12: ...1 0 10 and 11 4 11 4 7 Binary Mode Opcode Map 4 15 4 8 Source Mode Opcode Map 4 15 5 1 Word and Double word Storage in Big Endien Form 5 3 5 2 Program Status Word Register 5 18 5 3 Program Status Word...

Страница 13: ...Mode and Page Mode 13 1 13 2 External Code Fetch Nonpage Mode 13 4 13 3 External Data Read Nonpage Mode 13 4 13 4 External Data Write Nonpage Mode 13 5 13 5 External Code Fetch Page Mode 13 6 13 6 Ext...

Страница 14: ...51SB in Nonpage Mode 13 27 13 26 Address Space for Examples 5 and 6 13 28 13 27 Bus Diagram for Example 6 80C251SB in Page Mode 13 29 13 28 Bus Diagram for Example 7 80C251SB in Page Mode 13 30 14 1 S...

Страница 15: ...hitecture 5 6 5 4 Addressing Modes for Data Instructions in the MCS 251 Architecture 5 7 5 5 Bit addressable Locations 5 11 5 6 Addressing Two Sample Bits 5 12 5 7 Addressing Modes for Bit Instruction...

Страница 16: ...re A 5 A 8 Data Instructions A 6 A 9 High Nibble Byte 0 of Data Instructions A 6 A 10 Bit Instructions A 7 A 11 Byte 1 High Nibble for Bit Instructions A 7 A 12 PUSH POP Instructions A 8 A 13 Control...

Страница 17: ...CONTENTS xv TABLES Table Page C 4 Serial I O SFRs C 4 C 5 Timer Counter and Watchdog Timer SFRs C 4 C 6 Programmable Counter Array PCA SFRs C 5 C 7 Register File C 6...

Страница 18: ......

Страница 19: ...1 Guide to This Manual...

Страница 20: ......

Страница 21: ...ping of the address spaces of the MCS 51 architecture into the address spaces of the MCS 251 architecture Chapter 4 Device Configuration describes microcontroller features that are configured at devic...

Страница 22: ...es on chip and external clock sources and describes de vice resets including power on reset Chapter 12 Special Operating Modes provides an overview of the idle powerdown and on circuit emulation ONCE...

Страница 23: ...een the two possible meanings Variables in registers and signal names are commonly represented by x and y where x represents the first variable and y represents the second variable For example in regi...

Страница 24: ...represented by the register name followed by a period and the bit number For example PCON 4 is bit 4 of the power control register In some discussions bit names are used For example the name of PCON 4...

Страница 25: ...A microamps microamperes F microfarads s microseconds W microwatts 1 3 RELATED DOCUMENTS The following documents contain additional information that is useful in designing systems that incorporate the...

Страница 26: ...ormance Using MCS 251 Microcontroller Order Number 272671 Programming the 8XC251SB AP 710 Migrating from the MCS 51 Microcontroller to the MCS 251 Order Number 272672 Microcontroller 8XC251SB Software...

Страница 27: ...intel com design mcs96 Also visit Intel s Web site for financials history and news 1 4 2 CompuServe Forums Intel maintains several CompuServe forums that provide a means for you to gather information...

Страница 28: ...r number of each document that has been added revised or deleted dur ing the past eight weeks The daily update catalogs are numbered with the subject catalog number followed by a zero For example for...

Страница 29: ...1 on page 1 7 and respond to the system prompts During your first session the system asks you to register with the system oper ator by entering your name and location The system operator will set up y...

Страница 30: ......

Страница 31: ...2 Architectural Overview...

Страница 32: ......

Страница 33: ...251 microcontrollers share a set of common features 24 bit linear addressing and up to 16 Mbytes of memory a register based CPU with registers accessible as bytes words and double words a page mode fo...

Страница 34: ...erial I O Peripherals Port 2 Drivers P2 7 0 Port 0 Drivers P0 7 0 Port 3 Drivers P3 7 0 Port 1 Drivers P1 7 0 Data Address 24 Data Bus 8 Memory Address 16 MCS 251 Microcontroller Core System Bus and I...

Страница 35: ...lly programmed as a general I O signal or as a special function sig nal that supports the external bus or one of the on chip peripherals Ports P0 and P2 comprise a 16 line external bus which transmits...

Страница 36: ...ent for MCS 251 architecture instructions and binary mode is more efficient for MCS 51 architecture instructions In binary mode object code for an MCS 51 microcontroller runs on the 8XC251Sx without r...

Страница 37: ...XC251Sx register file has forty registers which can be accessed as bytes words and double words As in the MCS 51 architecture registers 0 7 consist of four banks of eight registers each where the acti...

Страница 38: ...mes This periph eral cycle is particular to the 8XC251Sx and not a characteristic of the MCS 251 architecture A one clock interval in a peripheral cycle is denoted by its state and phase For example t...

Страница 39: ...51SA and 8XC251SB have 1 Kbyte of on chip data RAM at locations 20H 41FH The 8XC251SP and 8XC251SQ have 512 bytes of on chip data RAM at locations 20H 21FH These RAM locations can be accessed with dir...

Страница 40: ...serving as a software watchdog timer Chapter 9 Program mable Counter Array describes this peripheral in detail 2 3 3 Serial I O Port The serial I O port provides one synchronous and three asynchronou...

Страница 41: ...3 Address Spaces...

Страница 42: ......

Страница 43: ...tecture and the MCS 51 architecture in terms of their address spaces 3 1 ADDRESS SPACES FOR MCS 251 MICROCONTROLLERS Figure 3 1 shows the memory space the SFR space and the register file for MCS 251 m...

Страница 44: ...SP SQ Register File on page 3 10 for a further description of the register file The SFR space can accommodate up to 512 8 bit special function registers with addresses S 000H S 1FFH Some of these loc...

Страница 45: ...ontrollers maps into region FF of the memory space for MCS 251 microcontrollers Assemblers for MCS 251 microcontrollers assemble code for MCS 51 microcontrollers into region FF and data accesses to co...

Страница 46: ...H 01 FFFFH Internal Data 128 bytes 00H 7FH Direct Indirect 00 0000H 00 007FH 128 bytes 80H FFH Indirect 00 0080H 00 00FFH SFRs 128 bytes S 80H S FFH Direct S 080H S 0FFH Register File 8 bytes R0 R7 Re...

Страница 47: ...on page 3 5 The 128 byte SFR space for MCS 51 microcontrollers is mapped into the 512 byte SFR space of the MCS 251 architecture starting at address S 080H as shown in Figure 3 3 This provides com ple...

Страница 48: ...FFFFH FE FFFFH FF FFFFH 01 0000H FE 0000H FF 0000H Memory Address Space 16 Mbytes 00 0080H 00 0020H 00 007FH 00 0000H 00 001FH 00 FFFFH Indirect and Displacement Addressing 16 Mbytes Direct Addressing...

Страница 49: ...FF 0000H External Memory External Memory Registers R0 R7 External Memory 00 0000H 00 FFFFH On chip ROM 8 or 16 Kbytes On chip RAM 512 or 1024 Bytes External Memory Eight byte configuration array FF FF...

Страница 50: ...byte is provided for general data storage Figure 3 5 Instruc tions cannot execute from on chip data RAM The data is accessible by direct indirect and dis placement addressing Locations 00 0020H 00 007...

Страница 51: ...to external code memory is transparent to the user 3 2 2 1 Accessing On chip Code Memory in Region 00 The 87C251SB SQ and the 83C251SB SQ can be configured so that the upper half of the 16 Kbyte on c...

Страница 52: ...al Memory Interface on page 4 8 and Chapter 13 External Memory Interface 3 3 8XC251SA SB SP SQ REGISTER FILE The 8XC251Sx register file consists of 40 locations 0 31 and 56 63 as shown in Figure 3 6 T...

Страница 53: ...4 Locations 32 55 are Reserved 63 62 61 60 59 58 57 56 R7 R6 R5 R4 R3 R2 R1 R0 R15 R14 R13 R12 R11 R10 R9 R8 DR20 DR16 DR28 DR24 WR6 WR4 WR2 WR0 WR14 WR12 WR10 WR8 WR22 WR20 WR18 WR16 WR30 WR28 WR26 W...

Страница 54: ...locations 8 31 and 56 63 are always accessible These locations are implemented as registers in the CPU Register file locations 32 55 are reserved and cannot be accessed Figure 3 7 Register File Locat...

Страница 55: ...0 001FH in the memory space 3 3 2 Dedicated Registers The register file has four dedicated registers R10 is the B register R11 is the accumulator ACC DR56 is the extended data pointer DPX DR60 is the...

Страница 56: ...e Register File and their Corresponding SFRs Bits in the PSW and PSW1 registers reflect the status of the accumulator There are no equivalent status indicators for the other registers R11 Accumulator...

Страница 57: ...nter SPX Figure 3 8 The byte at location 63 is the 8 bit stack pointer SP in the MCS 51 architecture The byte at location 62 is the stack pointer high SPH The two bytes allow the stack to extend to th...

Страница 58: ...receded by S to differentiate them from addresses in the memory space Unoccupied lo cations in the SFR space the shaded locations in Table 3 5 are unimplemented i e no register exists If an instructio...

Страница 59: ...000000 PSW1 00000000 D7 C8 T2CON 00000000 T2MOD xxxxxx00 RCAP2L 00000000 RCAP2H 00000000 TL2 00000000 TH2 00000000 CF C0 C7 B8 IPL0 x0000000 SADEN 00000000 SPH 00000000 BF B0 P3 11111111 IPH0 x0000000...

Страница 60: ...rogram Status Word 1 S D1H SP Stack Pointer LSB of SPX S 81H SPH Stack Pointer High MSB of SPX S BEH DPTR Data Pointer 2 bytes DPL Low Byte of DPTR S 82H DPH High Byte of DPTR S 83H DPXL Data Pointer...

Страница 61: ...nter 2 High Byte S CDH TCON Timer Counter 0 and 1 Control S 88H TMOD Timer Counter 0 and 1 Mode Control S 89H T2CON Timer Counter 2 Control S C8H T2MOD Timer Counter 2 Mode Control S C9H RCAP2L Timer...

Страница 62: ...Byte S ECH CCAP3L PCA Compare Capture Module 3 Low Byte S EDH CCAP4L PCA Compare Capture Module 4 Low Byte S EEH CCAP0H PCA Compare Capture Module 0 High Byte S FAH CCAP1H PCA Compare Capture Module 1...

Страница 63: ...4 Device Configuration...

Страница 64: ......

Страница 65: ...ps into the external memory See 4 5 Configuring the External Memory Interface Section 4 6 Opcode Configurations SRC discusses the choice of source mode or binary mode opcode arrangements 4 1 CONFIGURA...

Страница 66: ...internal addresses FF FFF8H and FF FFF9H CAUTION The eight highest addresses in the memory address space FF FFF8H FF FFFFH are reserved for the configuration array Do not read or write these locations...

Страница 67: ...FF9H x xFF8H UCONFIG1 UCONFIG0 Reserved This figure shows the addresses of configuration bytes UCONFIG1 and UCONFIG0 in external memory for several memory implementations For EA 0 the 8XC251Sx obtains...

Страница 68: ...2 XALE Extends the ALE pulse WSA1 0 Selects 0 1 2 or 3 pre programmed wait states for all regions except 01 WSB1 0 Selects 0 3 pre programmed wait states for memory region 01 EMAP Affects the externa...

Страница 69: ...from on chip nonvol atile memory at addresses FF FFF8H to FF FFFFH The configuration bytes are located at loca tions FF FFF8H and FF FFF9H If UCON is set e g UCON 1 the state of the EA pin at device r...

Страница 70: ...on RD1 0 bit codes specify an 18 bit 17 bit or 16 bit external address bus and address ranges for RD WR and PSEN See Table 4 2 1 PAGE Page Mode Select Clear this bit for page mode enabled with A15 8 D...

Страница 71: ...on chip code memory clear this bit to map the upper half of on chip code memory to region 00 data memory Maps FF 2000H FF 3FFFH to 00 E000H 00 FFFFH If this bit is set mapping does not occur and addre...

Страница 72: ...cture is the same as for the MCS 51 architecture with data D7 0 multiplexed with A7 0 on P0 External code fetches require two state times 4TOSC Page mode PAGE 0 The bus structure differs from the bus...

Страница 73: ...ry In some situations however a multiple mapping from internal memory to external memory does not preclude using more than one region For example for a device with on chip ROM OTPROM EPROM configured...

Страница 74: ...and WR Sections 13 8 2 and 13 8 3 show examples of memory designs with this option Figure 4 5 Internal External Address Mapping RD1 0 00 and 01 FF 01 PSEN WR PSEN WR A4218 02 FF FE 01 00 RD1 0 00 18...

Страница 75: ...2 PSEN WR PSEN WR FE FF 00 01 00 01 FE FF 64 Kbytes 128 Kbytes Notes 1 Single read signal 2 P3 7 RD A16 functions only as P3 7 Note 1 Compatible with MCS 51 microcontrollers 2 Cannot write to regions...

Страница 76: ...icrocontrollers which have separate external memory spaces for code and data 4 5 3 Wait State Configuration Bits You can add wait states to external bus cycles by extending the RD WR PSEN pulse and or...

Страница 77: ...hich set of opcodes is assigned to columns 6H through FH and which set is the alternative Binary mode and source mode refer to two ways of assigning opcodes to the instruction set for the MCS 251 arch...

Страница 78: ...e that was written for an MCS 51 microcontroller and you want to run it unmod ified on an MCS 251 microcontroller choose binary mode You can use the object code without reassembling the source code Yo...

Страница 79: ...4 8 Source Mode Opcode Map A4131 01 I II 0H 5H FH 6H 0H FH MCS 51 Architecture MCS 51 Architecture III 6H FH 0H FH MCS 251 Architecture A5H Prefix A4130 01 I III 0H 5H FH 6H 0H FH MCS 51 Architecture...

Страница 80: ...0 FFFFH EMAP 1 Mapping of on chip code memory to region 00 does not occur Addresses in the range 00 E000H 00 FFFFH access external RAM 4 8 INTERRUPT MODE INTR The INTR bit UCONFIG1 4 determines what b...

Страница 81: ...5 Programming...

Страница 82: ......

Страница 83: ...er to the two ways of assigning opcodes to the instruction set of the MCS 251 architecture Depending on the application one mode or the other may produce more efficient code The mode is established du...

Страница 84: ...ption of the register file see section 3 3 8XC251SA SB SP SQ Register File The code fragment in Figure 5 1 illustrates the storage of words and double words in big endien form 5 2 2 Register Notation...

Страница 85: ...prefixes 00 01 FF and the SFR prefix S are required Also software tools for the MCS 251 architecture permit 00 to be used for memory addresses 00H FFH and permit the prefix S to be used for SFR ad dre...

Страница 86: ...essing Modes for Control Instructions 5 3 DATA INSTRUCTIONS Data instructions consist of arithmetic logical and data transfer instructions for 8 bit 16 bit and 32 bit data This section describes the d...

Страница 87: ...bit immediate data into a dword register DRk place the data either into the upper word while leaving the lower word unchanged or into the lower word with a sign extension or a zero extension The incr...

Страница 88: ...l data RAM See the notes in section 5 3 1 Data Addressing Modes regarding the region of external data RAM that is addressed by instructions in the MCS 51 architecture Byte register Ri i 1 2 Registers...

Страница 89: ...7FH On chip RAM SFRs dir8 S 080H S 1FFH 2 or SFR mnemonic SFR address Direct 16 address bits 00 0000H 00 FFFFH dir16 00 0000H 00 FFFFH Indirect 16 address bits 00 0000H 00 FFFFH WR0 WR30 Indirect 24 a...

Страница 90: ...fset which is added to the base address 5 3 2 Arithmetic Instructions The set of arithmetic instructions is greatly expanded in the MCS 251 architecture The ADD and SUB instructions Table A 19 on page...

Страница 91: ...tains the first operand register The quotient is stored in the lower byte and the remainder is stored in the higher byte A 16 bit divide is similar The first operand is a word register and the result...

Страница 92: ...s 01H See section 3 3 2 Dedicated Registers The MOVC Move Code instruction moves a byte from code memory region FF to the accu mulator MOVS Move with Sign Extension and MOVZ Move with Zero Extension m...

Страница 93: ...5 5 The bit instructions that are unique to the MCS 251 architecture can address a wider range of bits than the instructions from the MCS 51 architecture There are some differences in the way the ins...

Страница 94: ...ocontrollers have a 24 bit program counter PC which allows a target instruction to be anywhere in the 16 Mbyte address space However as discussed in this section some con trol instructions restrict th...

Страница 95: ...addressing There are two types of indirect addressing for control instructions For the instructions LCALL WRj and LJMP WRj the target address is in the current 64 Kbyte region The 16 bit address in W...

Страница 96: ...Bit Addressing describes the bit addressing used in these instructions Compare conditional jumps test a condition resulting from a compare CMP instruction that is assumed to precede the jump instructi...

Страница 97: ...ruction address onto the stack and then changes the lower 11 bits of the PC to the 11 bit address specified by the instruction The call is to an address that is in the same 2 Kbyte block of memory as...

Страница 98: ...is useful for the development of emulations of an MCS 251 microcontrol ler 5 6 PROGRAM STATUS WORDS The Program Status Word PSW register and the Program Status Word 1 PSW1 register contain four types...

Страница 99: ...L SRA 4 X X X Program Control CJNE X X X DJNE X X NOTES 1 X the flag can be affected by the instruction 0 the flag is cleared by the instruction 2 The AC flag is affected only by operations on 8 bit o...

Страница 100: ...lag is useful for BCD arithmetic see Table 5 10 5 F0 Flag 0 This general purpose flag is available to the user 4 3 RS1 0 Register Bank Select Bits 1 and 0 These bits select the memory locations that c...

Страница 101: ...Negative Flag This bit is set if the result of the last logical or arithmetic operation was negative i e bit 15 1 Otherwise it is cleared 4 3 RS1 0 Register Bank Select Bits 0 and 1 Identical to the R...

Страница 102: ......

Страница 103: ...6 Interrupt System...

Страница 104: ......

Страница 105: ...Table 6 2 Interrupt System Special Function Registers is compared to the priority of other interrupts by the interrupt handler A high priority causes the handler to set an interrupt flag This signals...

Страница 106: ...1 INT1 Timer 1 0 1 0 1 ECF ECCFx IT0 IT1 5 A4149 01 IP Interrupt Enable Priority Enable EX0 ET0 EX1 ET1 EC ES ET2 TF0 CF CCFx RI TI TF2 EXF2 TF1 PCA Counter Overflow PCA Match or Capture Receive Trans...

Страница 107: ...hardware vectors to service routines only if the interrupt is negative edge triggered If the interrupt is level triggered the in terrupt service routine must clear the request bit External hardware m...

Страница 108: ...determine if TF2 or EXF2 generated the interrupt and then clear the bit Timer 2 interrupt is enabled by ET2 in register IE0 Table 6 3 Interrupt Control Matrix Interrupt Name Global Enable PCA Timer 2...

Страница 109: ...e Figure 9 8 on page 9 14 and Figure 9 9 on page 9 15 NOTE CCFx refers to 5 separate bits one for each PCA module CCF0 CCF1 CCF2 CCF3 CCF4 CCAPMx refers to 5 separate registers one for each PCA module...

Страница 110: ...rrupt Enable Setting this bit enables the PCA interrupt 5 ET2 Timer 2 Overflow Interrupt Enable Setting this bit enables the timer 2 overflow interrupt 4 ES Serial I O Port Interrupt Enable Setting th...

Страница 111: ...rrupted by any other in terrupt source Higher priority interrupts are serviced before lower priority interrupts The response to simultaneous occurrence of equal priority interrupts i e sampled within...

Страница 112: ...ority Bit High 2 IPH0 2 External Interrupt 1 Priority Bit High 1 IPH0 1 Timer 0 Overflow Interrupt Priority Bit High 0 IPH0 0 External Interrupt 0 Priority Bit High IPL0 Address S B8H Reset State X000...

Страница 113: ...with the request The subsequent minimum fixed sequence comprises the interrupt sample poll and request operations The variables consist of but are not limited to specific instructions in use at reque...

Страница 114: ...ari able is the completion time of an instruction cycle coincident with the occurrence of an interrupt request Worst case predictions typically use the longest executing instruction in an architecture...

Страница 115: ...o the execution unit If 9 states of a 10 state instruction have completed when the context switch is requested the total response time is 6 states with a context switch immediately after the final sta...

Страница 116: ...ate with the assumption the instruction state overlaps the request state therefore 16 bit DIV is 21 state times 1 20 states for latency calculations The calculations add fixed and vari able interrupt...

Страница 117: ...n the current 64 Kbyte region Finally three states are added for the current instruction to complete The actual latency is 26 states Worst case latency calculations predict 43 states for this example...

Страница 118: ...hree ensures at least one more instruction executes before the system vectors to additional interrupts if the in struction in progress is a RETI or any write to IE0 IPH0 or IPL0 The complete polling c...

Страница 119: ...Sx this causes a compatibility problem if INTR 1 in configuration byte CONFIG1 In this case the CPU pushes four bytes the three byte PC and PSW1 onto the stack when the routine is called and pops the...

Страница 120: ......

Страница 121: ...7 Input Output Ports...

Страница 122: ......

Страница 123: ...port 3 pins serve for both general purpose I O and alternate functions see Table 7 1 Table 7 1 Input Output Port Pin Descriptions Pin Name Type Alternate Pin Name Alternate Description Alternate Type...

Страница 124: ...r for general purpose I O or for its al ternate input or output function Table 7 1 To use a pin for general purpose output set or clear the corresponding bit in the Px register x 1 3 To use a pin for...

Страница 125: ...0 Structure Read Latch Read Pin Write to Latch Internal Bus Alternate Output Function D CL Q Q P3 x Latch Internal Pullup P3 x Alternate Input Function A2239 01 VCC Read Latch Read Pin Address Data C...

Страница 126: ...scusses the operation of port 0 and port 2 as the external address data bus NOTE Port 0 and port 2 are precluded from use as general purpose I O ports when used as address data bus drivers Port 0 inte...

Страница 127: ...DJNZ P3 LABEL MOV PX Y C move carry bit to bit Y of port X CLR PX Y clear bit Y of port X SETB PX Y set bit Y of port x It is not obvious that the last three instructions in this list are read modify...

Страница 128: ...t buffers and therefore the pin state update early in the instruction after the read modify write instruction cycle Logical zero to one transitions in port 1 port 2 and port 3 utilize an additional pu...

Страница 129: ...zero see VOL1 in the 8XC251Sx data sheet However the port 0 pins require external pullups to drive external gate inputs See the latest revision of the 8XC251Sx datasheet for com plete electrical desig...

Страница 130: ...ress byte In page mode port 2 uses a strong internal pullup FET to output ones or a strong internal pulldown FET to output zeros for the upper address byte and data Port 2 is in a high impedance state...

Страница 131: ...ata is written to port 0 just prior to the write WR pin asserting VOL Data remains valid until WR is undriven For read cycles data returned from external memory must appear at port 0 before the read R...

Страница 132: ......

Страница 133: ...8 Timer Counters and Watchdog Timer...

Страница 134: ......

Страница 135: ...d associated control and cap ture registers are implemented as addressable special function registers SFRs Table 8 1 briefly describes the SFRs referred to in this chapter Four of the SFRs provide pro...

Страница 136: ...ock signal with frequency FOSC 12 timer operation or an external input event counter operation S CCH S CDH TCON Timer 0 1 Control Register Contains the run control bits overflow flags interrupt flags...

Страница 137: ...r event counter in four modes of operation Figures 8 2 8 3 and 8 4 show the logical configuration of each mode Timer 0 is controlled by the four low order bits of the TMOD register Figure 8 5 and bits...

Страница 138: ...es timer 0 as a 13 bit timer which is set up as an 8 bit timer TH0 register with a modulo 32 prescalar implemented with the lower five bits of the TL0 register Figure 8 2 The upper three bits of the T...

Страница 139: ...0 operate as separate 8 bit timers Fig ure 8 4 This mode is provided for applications requiring an additional 8 bit timer or counter TL0 uses the timer 0 control bits C T0 and GATE0 in TMOD and TR0 an...

Страница 140: ...imer 1 can serve as the baud rate generator for the serial port Mode 2 is best suited for this purpose For normal timer operation GATE1 0 setting TR1 allows timer register TL1 to be increment ed by th...

Страница 141: ...1 with 5 bit prescalar TL1 0 1 Mode 1 16 bit timer counter 1 0 Mode 2 8 bit auto reload timer counter TL1 Reloaded from TH1 at overflow 1 1 Mode 3 Timer 1 halted Retains count 3 GATE0 Timer 0 Gate Whe...

Страница 142: ...f 5 TF0 Timer 0 Overflow Flag Set by hardware when the timer 0 register overflows Cleared by hardware when the processor vectors to the interrupt routine 4 TR0 Timer 0 Run Control Bit Set cleared by s...

Страница 143: ...ode 3 Halt Placing timer 1 in mode 3 causes it to halt and hold its count This can be used to halt timer 1 when the TR1 run control bit is not available i e when timer 0 is in mode 3 See the final par...

Страница 144: ...order bits of the TMOD register Figure 8 5 to specify mode 1 for timer 0 C T0 0 to select FOSC 12 as the timer input and GATE0 1 to select INT0 as timer run control 2 Enter an initial value of all zer...

Страница 145: ...ut The operating modes are described in the following paragraphs Block diagrams in Figures 8 7 through 8 10 show the timer 2 configuration for each mode 8 6 1 Capture Mode In the capture mode timer 2...

Страница 146: ...register provides two options Figure 8 12 If EXEN2 0 timer 2 counts up to FFFFH and sets the TF2 overflow flag The overflow condition loads the 16 bit value in the re load capture registers RCAP2H RCA...

Страница 147: ...low timer 2 counts down Timer underflow occurs when the count in the timer registers TH2 TL2 equals the value stored in RCAP2H and RCAP2L The underflow sets the TF2 bit and reloads FFFFH into the tim...

Страница 148: ...clock timer 2 has a programmable frequency range of 61 Hz to 4 MHz The generated clock signal is brought out to the T2 pin Timer 2 is programmed for the clock out mode as follows 1 Set the T2OE bit i...

Страница 149: ...2 Modes of Operation Mode RCLK OR TCLK in T2CON CP RL2 in T2CON T2OE in T2MOD Auto reload Mode 0 0 0 Capture Mode 0 1 0 Baud Rate Generator Mode 1 X X Programmable Clock Out X 0 1 Interrupt Request T2...

Страница 150: ...ac cess to the WDT Two operations control the WDT Device reset clears and disables the WDT see section 11 4 Reset Writing a specific two byte sequence to the WDTRST register clears and enables the WD...

Страница 151: ...or timer 1 overflow pulses TCLK 0 as the baud rate generator for serial port modes 1 and 3 3 EXEN2 Timer 2 External Enable Bit Setting EXEN2 causes a capture or reload to occur as a result of a negat...

Страница 152: ...power reduction modes deserves special attention The WDT continues to count while the microcontroller is in idle mode This means the user must service the WDT during idle One approach is to use a peri...

Страница 153: ...9 Programmable Counter Array...

Страница 154: ......

Страница 155: ...9 9 For a list of SFRs associated with the PCA see Table 9 1 For an address map of all SFRs see Table 3 5 on page 3 17 Port 1 provides external I O for the PCA on a shared basis with other functions...

Страница 156: ...byte register When CL overflows the CH high byte register increments after two oscil lator periods when CH overflows it sets the PCA overflow flag CF in the CCON register gen erating a PCA interrupt r...

Страница 157: ...er writing to them is inhibited while they are counting i e when the CR bit is set Figure 9 1 Programmable Counter Array 16 bit Bus CL 8 Bits CH 8 Bits CF Interrupt Request FOSC 12 PCA Timer Counter C...

Страница 158: ...cycle of the output waveform S FBH S EBH CCAP2H CCAP2L PCA Module 2 Compare Capture Registers This register pair stores the comparison value or the captured value In the PWM mode the low byte registe...

Страница 159: ...na tions of the available modes Other bit combinations are invalid and produce undefined results The compare capture modules perform their programmed functions when their common time base the PCA time...

Страница 160: ...to the compare capture registers CCAPxH CCAPxL and to set the module s compare capture flag CCFx in the CCON register If the corresponding in terrupt enable bit ECCFx in the CCAPMx register is set Fig...

Страница 161: ...peration 2 Select the input signal for the PCA timer counter 3 Load the comparison value into the module s compare capture register pair 4 Set the PCA timer counter run control bit 5 After a match cau...

Страница 162: ...9 3 on page 9 14 lists the bit combinations for selecting module modes A match between the PCA timer counter and the compare capture registers CCAPxH CCAPxL toggles the CEXx pin and sets the module s...

Страница 163: ...are used in applications that are subject to electrical noise power glitches elec trostatic discharges etc or where high reliability is required In addition to the 8XC251Sx s 14 bit hardware WDT the P...

Страница 164: ...then later re enable it The first two options are more reliable because the WDT is not disabled as in the third option The second option is not recommended if other PCA modules are in use since the fi...

Страница 165: ...ter CL is continuously compared with the value in the low byte of the compare capture register CCAPxL When CL CCAPxL the output waveform Figure 9 6 is low When a match occurs CL CCAPxL the output wave...

Страница 166: ...The highest frequency occurs when the FOSC 4 input is selected for the PCA tim er counter For FOSC 16 MHz this is 15 6 KHz To program a compare capture module for the PWM mode set the ECOMx and PWMx...

Страница 167: ...to run during idle mode 6 WDTE Watchdog Timer Enable WDTE 1 enables the watchdog timer output on PCA module 4 WDTE 0 disables the PCA watchdog timer output 5 3 Reserved The values read from these bit...

Страница 168: ...s This generates a PCA interrupt request if the ECCFx interrupt enable bit in the corresponding CCAPMx register is set Must be cleared by software Table 9 3 PCA Module Modes ECOMx CAPPx CAPNx MATx TOG...

Страница 169: ...apture triggered by a positive edge on pin CEXx 4 CAPNx Capture Mode Negative CAPNx 1 enables the capture function with capture triggered by a negative edge on pin CEXx 3 MATx Match Set ECOMx and MATx...

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Страница 171: ...10 Serial I O Port...

Страница 172: ......

Страница 173: ...serial port special function registers are described in Table 10 2 Figure 10 1 is a block diagram of the serial port For the three asynchronous modes the UART transmits on the TXD pin and receives on...

Страница 174: ...rial port operating mode SCON enables and disables the receiver framing bit error detection multiprocessor communication automatic address recognition and the serial port interrupt bits 98H SADDR Seri...

Страница 175: ...operating mode SM0 SM1 Mode Description Baud Rate 0 0 0 Shift register FOSC 12 0 1 1 8 bit UART Variable 1 0 2 9 bit UART FOSC 32 or FOSC 64 1 1 3 9 bit UART Variable Select by programming the SMOD bi...

Страница 176: ...e 0 10 2 1 1 Transmission Mode 0 Follow these steps to begin a transmission 1 Write to the SCON register clearing bits SM0 SM1 and REN 2 Write the byte to be transmitted to the SBUF register This writ...

Страница 177: ...ck signal pulse and the LSB D0 is sampled on the RXD pin at S5P2 The D0 bit is then shift ed into the shift register After eight shifts at S6P2 of every peripheral cycle the LSB D7 is shift ed into th...

Страница 178: ...n On receive the ninth bit is read from the RB8 bit in the SCON register On transmit the ninth data bit is written to the TB8 bit in the SCON register Alternatively you can use the ninth bit as a comm...

Страница 179: ...ocessor com munication feature is enabled the serial port can differentiate between data frames ninth bit clear and address frames ninth bit set This allows the microcontroller to function as a slave...

Страница 180: ...recognition features cannot be enabled in mode 0 i e setting the SM2 bit in the SCON register in mode 0 has no effect To support automatic address recognition a device is identified by a given address...

Страница 181: ...nd C the master must send an address with bit 0 set bit 1 clear and bit 2 clear e g 1111 0001 10 5 2 Broadcast Address A broadcast address is formed from the logical OR of the SADDR and SADEN register...

Страница 182: ...nt Table 10 3 summarizes the baud rates that can be used for the four serial I O modes 10 6 1 Baud Rate for Mode 0 The baud rate for mode 0 is fixed at FOSC 12 10 6 2 Baud Rates for Mode 2 Mode 2 has...

Страница 183: ...TMOD register Figure 8 5 on page 8 7 Select timer mode 0 3 by programming the M1 M0 bits in the TMOD register In most applications timer 1 is configured as a timer in auto reload mode high nibble of...

Страница 184: ...r 2 into its baud rate generator mode Figure 10 5 In this mode a rollover in the TH2 register does not set the TF2 bit in the T2CON register Also a high to low transition at the T2EX pin sets the EXF2...

Страница 185: ...Rate Generator s RCLCK Bit TCLCK Bit Receiver Baud Rate Generator Transmitter Baud Rate Generator 0 0 Timer 1 Timer 1 0 1 Timer 1 Timer 2 1 0 Timer 2 Timer 1 1 1 Timer 2 Timer 2 T2EX 2 T2 Timer 1 Ove...

Страница 186: ...esults of a read or write may not be accurate In addition you may read but not write to the RCAP2 registers a write may overlap a reload and cause write and or reload errors Table 10 6 lists commonly...

Страница 187: ...11 Minimum Hardware Setup...

Страница 188: ......

Страница 189: ...dware setup that employs the on chip oscillator for the system clock and provides power on reset Control signals and Ports 0 1 2 and 3 are not shown See sections 11 3 Clock Sources and 11 4 4 Power on...

Страница 190: ...d VSS They are not required for proper de vice operation thus the 8XC251Sx is compatible with designs that do not provide connections to these pins 11 2 2 Unused Pins To provide stable predictable per...

Страница 191: ...high quality components C1 C2 30 pF is adequate for this application Pins XTAL1 and XTAL2 are protected by on chip electrostatic discharge ESD devices D1 and D2 which are diodes parasitic to the RF FE...

Страница 192: ...different capacitor values and circuit configuration Consult the manufacturer s data sheet for specific information 11 3 3 External Clock To operate the CHMOS 8XC251Sx from an external clock connect...

Страница 193: ...k capacitance i e the Miller effect at power on Once the input waveform requirements are met the input capacitance remains under 20 pF Figure 11 4 External Clock Drive Waveforms 11 4 RESET A device re...

Страница 194: ...hardware WDT overflow or the PCA WDT comparison match generates a reset signal WDT initiated resets have the same effect as an external reset See section 8 7 Watchdog Timer and section 9 3 5 PCA Watc...

Страница 195: ...at power on connect the RST pin to the VCC pin through a 1 F capacitor as shown in Figure 11 1 When VCC is applied the RST pin rises to VCC then decays exponentially as the capacitor charg es The time...

Страница 196: ...8XC251SA SB SP SQ USER S MANUAL 11 8 Figure 11 5 Reset Timing Sequence RST XTAL Internal Reset Routine ALE A4103 01 PSEN 64 TOSC 1 2 3 32 First ALE...

Страница 197: ...12 Special Operating Modes...

Страница 198: ......

Страница 199: ...er off flag and two general purpose flags 12 2 1 Serial I O Control Bits The SMOD1 bit in the PCON register is a factor in determining the serial I O baud rate See Fig ure 12 1 and section 10 6 Baud R...

Страница 200: ...a zero to this bit 4 POF Power Off Flag Set by hardware as VCC rises above 3 V to indicate that power has been off or VCC had fallen below 3 V and that on chip volatile memory is indeterminate Set or...

Страница 201: ...eset Don t Care Weak High Weak High Floating Weak High Weak High Weak High Idle Internal 1 1 Data Data Data Data Idle External 1 1 Floating Data Data Data Powerdown Internal 0 0 Data Data Data Data Po...

Страница 202: ...ion of the program memory Internal program memory the ALE and PSEN pins are pulled high and the ports 0 1 2 and 3 pins are reading data Table 12 1 External program memory the ALE and PSEN pins are pul...

Страница 203: ...C251Sx and vectors the CPU to address FF 0000H NOTE During the time that execution resumes the internal RAM cannot be accessed however it is possible for the port pins to be accessed To avoid unexpect...

Страница 204: ...t set the IE register EX0 and or EX1 bit s The external interrupt used to exit powerdown mode must be configured as level sensitive and must be assigned the highest priority In addition the duration o...

Страница 205: ...ets and the reset waveforms in Figure 11 5 on page 11 8 2 While holding RST asserted apply and hold logic levels to I O pins as follows PSEN low P0 7 5 low P0 4 high P0 3 0 low i e port 0 10H 3 Deasse...

Страница 206: ......

Страница 207: ...13 External Memory Interface...

Страница 208: ......

Страница 209: ...r page mode or nonpage mode Page mode pro vides increased performance by reducing the time for external code fetches Page mode does not apply to code fetches from on chip memory The reset routine conf...

Страница 210: ...0 All addresses 0 1 All addresses 1 0 All addresses 1 1 All addresses 80 0000H RD O Read or 17th Address Bit A16 Read signal output to external data memory or 17th external address bit A16 depending...

Страница 211: ...es It also shows the activity on the bus for nonpage mode and page mode bus cycles with no wait states There are three types of nonpage mode bus cycles code read data read and data write There are fou...

Страница 212: ...ite bus cycles Figure 13 4 execute in approximately three state times For the write cycle Figure 13 4 a third state is appended to provide recovery time for the bus Note that the write signal WR is as...

Страница 213: ...ss it again requires a two state bus cy cle The following external code fetches are always page miss cycles the first external code fetch after a page rollover the first external code fetch after an e...

Страница 214: ...ed on port 0 and memory places the in struction byte on port 2 Notice that a page hit reduces the available address access time by one state Therefore faster memories may be required to support page m...

Страница 215: ...External Data Read Page Mode Figure 13 7 External Data Write Page Mode A17 A16 P0 P2 ALE RD PSEN State 1 State 2 XTAL State 3 A2811 04 A15 8 D7 0 A17 A16 A7 0 A17 A16 P0 P2 ALE WR State 1 State 2 XTA...

Страница 216: ...SP SQ supports traditional real time wait state operations for dy namic bus control The real time wait state operations are enabled with the WCON SFR bits at address S 0A7H The device can also be conf...

Страница 217: ...Mode One RD PSEN Wait State Figure 13 9 External Data Write Nonpage Mode One WR Wait State P0 A17 A16 P2 ALE RD PSEN State 1 State 2 XTAL State 3 A2812 04 A7 0 D7 0 A17 A16 A15 8 P0 A17 A16 P2 ALE WR...

Страница 218: ...TH REAL TIME WAIT STATES In addition to fixed length wait states such as RD WR PSEN and ALE the 8XC251SA SB SP SQ offers a real time wait state The programmer can dynamically adjust the delay of the r...

Страница 219: ...o drive address signal A17 in some memory designs The A17 address signal always takes priority over other alternate functions in this case both PCA 4 and WCLK Even if RTWCE is enabled in WCON 1 the WC...

Страница 220: ...tasheet 13 5 2 Real time WAIT CLOCK Enable RTWCE The real time WAIT CLOCK output is driven at port 1 7 WCLK by writing a logical 1 to the WCON 1 RTWCE bit at S A7H When enabled the WCLK output produce...

Страница 221: ...External Data Write Nonpage Mode RT Wait State A0 A7 WCLK ALE RD PSEN WAIT P0 P2 A8 A15 A5007 01 State 1 State 2 State 3 State 1 next cycle A0 A7 D0 D7 stretched A8 A15 stretched RD PSEN stretched A0...

Страница 222: ...xternal Data Write Page Mode RT Wait State A8 A15 WCLK ALE RD PSEN WAIT P2 P0 A0 A7 A5008 01 State 1 State 2 State 3 State 1 next cycle A8 A15 D0 D7 stretched A0 A7 stretched RD PSEN stretched A8 A15...

Страница 223: ...3 16 If the external memory is set up for page mode it places UCONFIG0 on P2 as D7 0 overwriting A15 8 FFH If external memory is set up for nonpage mode A15 8 is not overwritten The 8XC251Sx examines...

Страница 224: ...hose on the 8XC51FX For an external memory instruction using a 16 bit address the port pins carry address and data bits during the bus cycle However if the instruction uses an 8 bit address e g MOVX R...

Страница 225: ...the instruction uses an 8 bit address e g MOVX Ri the contents of P2 are driven onto the pins when data is not on the pins These logic levels can be used to select 256 bit pages in external memory Dur...

Страница 226: ...ace on page 4 8 Figure 4 5 on page 4 10 and Figure 4 6 on page 4 11 depict the mapping of internal memory space into external memory 13 8 1 Example 1 RD1 0 00 18 bit Bus External Flash and RAM In this...

Страница 227: ...ORY INTERFACE Figure 13 18 Address Space for Example 1 A4220 02 1056 Bytes On chip RAM 01 00 FE FF 128 Kbytes External Flash Address Space 256 Kbytes 0000H FFFFH 0420H FFFFH 128 Kbytes 1056 Bytes Exte...

Страница 228: ...hat PSEN is asserted for all reads and RD functions as A16 RD1 0 01 Figure 13 20 shows how the external flash and RAM are addressed in the internal address space Addresses 0420H 7FFFH in external RAM...

Страница 229: ...MORY INTERFACE Figure 13 20 Address Space for Example 2 A4168 03 1056 Bytes On chip RAM 01 00 FE FF 64 Kbytes External Flash Address Space 256 Kbytes 0000H FFFFH 0420H 32 Kbytes 1056 Bytes External RA...

Страница 230: ...of external RAM Figure 13 21 The 87C251SB 83C251SB is configured so that RD functions as A16 and PSEN is asserted for all reads Figure 13 22 shows how the external RAM is addressed in the internal add...

Страница 231: ...NTERFACE Figure 13 22 Address Space for Example 3 A4169 03 1056 Bytes On chip RAM 01 00 FE FF 16 Kbytes On chip Code Memory Address Space 256 Kbytes 0000H FFFFH 0420H FFFFH 128 Kbytes 1056 Bytes Exter...

Страница 232: ...ion leaves P3 7 RD A16 available for general I O RD1 0 10 A maximum of 64 Kbytes of external memory can be used and all regions of internal memory map into the single 64 Kbyte region in external memor...

Страница 233: ...INTERFACE Figure 13 24 Address Space for Example 4 A4224 02 1056 Bytes On chip RAM 01 00 FE FF 16 Kbytes On chip Code Memory Address Space 256 Kbytes FFFFH 0420H FFFFH External RAM 64 Kbytes 1056 Byte...

Страница 234: ...ss the real time wait states are selected see Figure 13 11 on page 13 11 The examples that follow illustrate two possibilities for addressing the external RAM 13 8 5 1 An Application Requiring Fast Ac...

Страница 235: ...INTERFACE Figure 13 25 Bus Diagram for Example 5 80C251SB in Nonpage Mode A4145 01 A7 0 Latch A15 8 A D7 0 EPROM 64 Kbytes OE CE A15 8 A7 0 D7 0 PSEN 80C251SB RD WR EA P2 P0 D7 0 A15 8 A7 0 RAM 64 Kby...

Страница 236: ...ytes On chip RAM 01 00 FE FF 64 Kbytes External EPROM Address Space 256 Kbytes 0000H FFFFH 0420H FFFFH External RAM 64 Kbytes 1056 Bytes 1056 Bytes On chip RAM 01 00 FE FF 64 Kbytes External EPROM Add...

Страница 237: ...for addresses 7F FFFFH and PSEN is asserted for addresses 80 0000 This system is the same as Example 5 Figure 13 25 except that it operates in page mode Ac cordingly the two systems have the same mem...

Страница 238: ...e upper address bits A15 0 and the data D7 0 while port 0 carries only the lower address bits A7 0 The 80C251SB is configured for a single read signal PSEN The 128 Kbytes of external flash are accesse...

Страница 239: ...14 Programming and Verifying Nonvolatile Memory...

Страница 240: ......

Страница 241: ...g the signature bytes 3 bytes Programming instructions apply to the 87C251Sx one time programmable ROM OTPROM and erasable programmable ROM EPROM Verify instructions apply to the 87C251Sx the 83C251Sx...

Страница 242: ...ternal addresses For a detailed discussion of device configuration see Chapter 4 ROM OTPROM EPROM devices have on chip user code memory at FF 0000 FF 1FFFH 8 Kbytes or FF 0000H FF 3FFFH 16 Kbytes Addr...

Страница 243: ...memory for devices without ROM OTPROM EPROM Figure 4 2 on page 4 3 14 3 GENERAL SETUP Figure 14 1 shows the general setup for programming and verifying nonvolatile memory on the 87C251Sx The figure a...

Страница 244: ...gh 29H data FFF8H FFFFH 4 Program Mode Lock Bits 87C251Sx High Low 5 V 12 75 V 25 Pulses 6BH data 0001H 0003H 1 2 Verify Mode Lock bits 87C251Sx 83C251Sx High Low 5 V High 2BH data 0000H 3 Program Mod...

Страница 245: ...on chip code memory and the configuration bytes and 25 times for the encryption array and the lock bits 6 Reduce the voltage on the VPP pin to 5 V 7 If the procedure is program immediate verify go to...

Страница 246: ...controller for operation in the appropriate mode according to Table 14 1 2 Input the 16 bit address on ports P1 and P3 3 Wait for the data on port P2 to become valid TAVQV 48 clock cycles see the dat...

Страница 247: ...8H and UCONFIG1 FF FFF9H are imple mented the remaining bytes are reserved for future use See Figure 4 1 on page 4 2 Figure 4 3 on page 4 6 and Figure 4 4 on page 4 7 To program the 87C251Sx configura...

Страница 248: ...cryption array perform the procedure described in section 14 4 Programming Algorithm using the program encryption array mode Table 14 1 To preserve the secrecy of the encryption key byte sequence the...

Страница 249: ...f nonvolatile memory on the 83C251Sx see 14 6 Programmable Functions for each function desired Or more directly perform the verification procedure described in 14 5 Verify Algorithm using the appropri...

Страница 250: ......

Страница 251: ...A Instruction Set Reference...

Страница 252: ......

Страница 253: ...ons Table A 19 Compare Instructions Table A 20 Increment and Decrement Instructions Table A 21 Multiply Divide and Decimal adjust Instructions Table A 22 Logical Instructions Table A 23 Move Instructi...

Страница 254: ...ry location 00 0000H 00 FFFFH addressed indirectly through word register WR0 WR30 WRj Data RAM location 00 0000H 00 FFFFH addressed indirectly dis16 through a word register WR0 WR30 displacement value...

Страница 255: ...MCS 251 Arch MCS 51 Arch bit y y y A directly addressed bit in memory locations 00 0020H 00 007FH or in any defined SFR A binary representation of the bit number 0 7 within a byte bit51 A directly add...

Страница 256: ...Z rel AJMP addr11 XRL dir8 A XRL dir8 data XRL A data XRL A dir8 XRL A Ri XRL A Rn 7 JNZ rel ACALL addr11 ORL CY bit JMP A DPTR MOV A data MOV dir8 data MOV Ri data MOV Rn data 8 SJMP rel AJMP addr11...

Страница 257: ...s ORL Rm Rm ORL WRj WRj ORL reg op2 2 5 JSGE rel MOV WRj dis WRj ANL Rm Rm ANL WRj WRj ANL reg op2 2 6 JE rel MOV WRj DRk dis XRL Rm Rm XRL WRj WRj XRL reg op2 2 7 JNE rel MOV DRk dis WRj MOV op1 reg...

Страница 258: ...r Oper Rm dir16 x E m 0011 dir16 addr high dir16 addr low Oper WRj dir16 x E j 2 0111 dir16 addr high dir16 addr low Oper DRk dir16 1 x E k 4 1111 dir16 addr high dir16 addr low Oper Rm WRj x E j 2 10...

Страница 259: ...nstruction as given in Table A 10 Table A 10 Bit Instructions Instruction Byte 0 x Byte 1 Byte 2 Byte 3 1 Bit Instr dir8 A 9 xxxx 0 bit dir8 addr rel addr Table A 11 Byte 1 High Nibble for Bit Instruc...

Страница 260: ...4 0001 POP Rm D A m 1000 POP WRj D A j 2 1001 POP DRk D A k 4 1011 Table A 13 Control Instructions Instruction Byte 0 x Byte 1 Byte 2 Byte 3 EJMP addr24 8 A addr 23 16 addr 15 8 addr 7 0 ECALL addr24...

Страница 261: ...m k 4 dis 15 8 dis 7 0 MOV DRk dis WRj 7 9 j 2 k 4 dis 15 8 dis 7 0 MOVS WRj Rm 1 A j 2 m MOVZ WRj Rm 0 A j 2 m MOV WRj WRj 0 B j 2 1000 j 2 0000 MOV WRj DRk 0 B k 4 1010 j 2 0000 MOV WRj WRj 1 B j 2...

Страница 262: ...NC DRk short 0 B k 4 11 ss 4 DEC Rm short 1 B m 00 ss 5 DEC WRj short 1 B j 2 01 ss 6 DEC DRk short 1 B k 4 11 ss Table A 16 Encoding for INC DEC ss short 00 1 01 2 10 4 Table A 17 Shifts Instruction...

Страница 263: ...Execution Times for Instructions that Access the Port SFRs The execution times for some instructions increase when the instruction accesses a port SFR Px x 0 3 as opposed to any other SFR Table A 18 l...

Страница 264: ...dir8 data 3 3 2 4 6 8 ANL dir8 A 2 2 2 4 6 8 ANL Rm dir8 3 2 1 2 3 4 CLR bit 4 3 2 4 6 8 CLR bit51 2 2 2 4 6 8 CMP Rm dir8 3 2 1 2 3 4 CPL bit 4 3 2 4 6 8 CPL bit51 2 2 2 4 6 8 DEC dir8 2 2 2 4 6 8 I...

Страница 265: ...8 SETB bit51 2 2 2 4 6 8 SUB Rm dir8 3 2 1 2 3 4 SUBB A dir8 1 1 1 2 3 4 XCH A dir8 3 3 2 4 6 8 XRL A dir8 1 1 1 2 3 4 XRL dir8 data 3 3 2 4 6 8 XRL dir8 A 2 2 2 4 6 8 XRL Rm dir8 3 2 1 2 3 4 Table A...

Страница 266: ...g to from dword reg 3 5 2 4 Rm data Immediate 8 bit data to from byte reg 4 3 3 2 WRj data16 Immediate 16 bit data to from word reg 5 4 4 3 DRk 0data16 16 bit unsigned immediate data to from dword reg...

Страница 267: ...3 3 2 WRj data16 Word reg with immediate 16 bit data 5 4 4 3 DRk 0data16 Dword reg with zero extended 16 bit immediate data 5 6 4 5 DRk 1data16 Dword reg with one extended 16 bit immediate data 5 6 4...

Страница 268: ...cell denotes an instruction in the MCS 51 architecture 2 If this instruction addresses an I O port Px x 0 3 add 2 to the number of states Table A 22 Summary of Multiply Divide and Decimal adjust Instr...

Страница 269: ...reg 3 3 2 2 Rm data 8 bit data to byte reg 4 3 3 2 WRj data16 16 bit data to word reg 5 4 4 3 Rm dir8 Dir addr to byte reg 4 3 3 3 2 3 WRj dir8 Dir addr to word reg 4 4 3 3 Rm dir16 Dir addr 64K to by...

Страница 270: ...cal OR ORL dest src dest opnd dest opnd V src opnd Logical Exclusive OR XRL dest src dest opnd dest opnd src opnd Clear CLR A A 0 Complement CPL A Ai Ai Rotate RXX A 1 Shift SXX Rm or Wj 1 SWAP A A3 0...

Страница 271: ...yte 3 3 3 3 dir8 Ri Indir RAM to dir byte 2 3 3 4 dir8 data Immediate data to dir byte 3 3 3 3 3 3 Ri A Acc to indir RAM 1 3 2 4 Ri dir8 Dir byte to indir RAM 2 3 3 4 Ri data Immediate data to indir R...

Страница 272: ...e reg 5 6 4 5 WRj WRj dis16 Indir addr with disp 64K to word reg 5 7 4 6 Rm DRk dis24 Indir addr with disp 16M to byte reg 5 7 4 6 WRj DRk dis24 Indir addr with disp 16M to word reg 5 8 4 7 WRj dis16...

Страница 273: ...t addr 4 1 5 1 5 Table A 24 Summary of Move Instructions Continued Move 2 MOV dest src destination src opnd Move with Sign Extension MOVS dest src destination src opnd with sign extend Move with Zero...

Страница 274: ...XCHD A Ri Acc and low nibble in on chip RAM 8 bit addr 1 4 2 5 PUSH dir8 Push dir byte onto stack 2 2 2 2 data Push immediate data onto stack 4 4 3 3 data16 Push 16 bit immediate data onto stack 5 5...

Страница 275: ...1 1 1 bit51 Complement dir bit 2 2 2 2 2 2 bit Complement dir bit 4 4 2 3 3 2 ANL CY bit51 AND dir bit to carry 2 1 3 2 1 3 CY bit AND dir bit to carry 4 3 3 3 2 3 ANL CY bit51 AND complemented dir b...

Страница 276: ...mp indir relative to the DPTR 1 5 1 5 JC rel Jump if carry is set 2 1 4 2 1 4 JNC rel Jump if carry not set 2 1 4 2 1 4 JB bit51 rel Jump if dir bit is set 3 2 5 3 2 5 bit rel Jump if dir bit of 8 bit...

Страница 277: ...o reg and jump if not equal 3 2 5 4 3 6 Ri data rel Compare immediate to indir and jump if not equal 3 3 6 4 4 7 DJNZ Rn rel Decrement reg and jump if not zero 2 2 5 3 3 6 dir8 rel Decrement dir byte...

Страница 278: ...nating bits 15 11 of the incremented PC opcode bits 7 5 and the second byte of the instruction The subroutine called must therefore start within the same 2 Kbyte page of the program memory as the firs...

Страница 279: ...t out of bit 7 or a carry out of bit 7 but not bit 6 the OV flag is set When adding signed integers the OV flag indicates a negative number produced as the sum of two positive operands or a positive s...

Страница 280: ...ding Source Mode Encoding Operation ADD A A dir8 ADD A Ri Binary Mode Source Mode Bytes 1 2 States 2 3 Hex Code in Binary Mode Encoding Source Mode A5 Encoding Operation ADD A A Ri ADD A Rn Binary Mod...

Страница 281: ...js ADD DRkd DRks Binary Mode Source Mode Bytes 3 2 States 5 4 Hex Code in Binary Mode A5 Encoding Source Mode Encoding Operation ADD DRkd DRkd DRks ADD Rm data Binary Mode Source Mode Bytes 4 3 States...

Страница 282: ...e Mode Encoding Operation ADD DRk DRk data16 ADD Rm dir8 Binary Mode Source Mode Bytes 4 3 States 3 2 If this instruction addresses a port Px x 0 3 add 1 state Hex Code in Binary Mode A5 Encoding Sour...

Страница 283: ...r16 ADD WRj dir16 Binary Mode Source Mode Bytes 5 4 States 4 3 Encoding Hex Code in Binary Mode A5 Encoding Source Mode Encoding Operation ADD WRj WRj dir16 ADD Rm WRj Binary Mode Source Mode Bytes 4...

Страница 284: ...bit 7 or a carry out of bit 7 but not bit 6 the OV flag is set When adding signed integers the OV flag indicates a negative number produced as the sum of two positive operands or a positive sum from t...

Страница 285: ...ncoding Source Mode Encoding Operation ADDC A A CY dir8 ADDC A Ri Binary Mode Source Mode Bytes 1 2 States 2 3 Hex Code in Binary Mode Encoding Source Mode A5 Encoding Operation ADDC A A CY Ri ADDC A...

Страница 286: ...Bytes 2 2 States 3 3 Hex Code in Binary Mode Encoding Source Mode Encoding Operation AJMP PC PC 2 PC 10 0 page address ANL dest src Function Logical AND Description Performs the bitwise logical AND op...

Страница 287: ...er or accumulator at run time The instruction ANL P1 01110011B clears bits 7 3 and 2 of output port 1 Variations ANL dir8 A Binary Mode Source Mode Bytes 2 2 States 2 2 If this instruction addresses a...

Страница 288: ...ding Source Mode Encoding Operation ANL A A dir8 ANL A Ri Binary Mode Source Mode Bytes 1 2 States 2 3 Hex Code in Binary Mode Encoding Source Mode A5 Encoding Operation ANL A A Ri ANL A Rn Binary Mod...

Страница 289: ...Rm data Binary Mode Source Mode Bytes 4 3 States 3 2 Hex Code in Binary Mode A5 Encoding Source Mode Encoding Operation ANL Rm Rm data ANL WRj data16 Binary Mode Source Mode Bytes 5 4 States 4 3 Encod...

Страница 290: ...de Bytes 4 3 States 4 3 Hex Code in Binary Mode A5 Encoding Source Mode Encoding Operation ANL WRj WRj dir8 ANL Rm dir16 Binary Mode Source Mode Bytes 5 4 States 3 2 Encoding Hex Code in Binary Mode A...

Страница 291: ...Operation ANL Rm Rm DRk ANL CY src bit Function Logical AND for bit variables Description If the Boolean value of the source bit is a logical 0 clear the CY flag otherwise leave the CY flag in its cur...

Страница 292: ...Binary Mode Encoding Source Mode Encoding Operation ANL CY CY bit51 ANL CY bit51 Binary Mode Source Mode Bytes 2 2 States 1 1 If this instruction addresses a port Px x 0 3 add 1 state Hex Code in Bin...

Страница 293: ...wo operands allow four addressing mode combinations the accumulator may be compared with any directly addressed byte or immediate data and any indirect RAM location or working register can be compared...

Страница 294: ...A data THEN CY 1 ELSE CY 0 CJNE A dir8 rel Binary Mode Source Mode Not Taken Taken Not Taken Taken Bytes 3 3 3 3 States 3 6 3 6 Hex Code in Binary Mode Encoding Source Mode Encoding Operation PC PC 3...

Страница 295: ...s 2 5 3 6 Hex Code in Binary Mode Encoding Source Mode A5 Encoding Operation PC PC 3 IF Rn data THEN PC PC relative offset IF Rn data THEN CY 1 ELSE CY 0 CLR A Function Clear accumulator Description C...

Страница 296: ...instructions with CY as the operand Example Port 1 contains 5DH 01011101B After executing the instruction CLR P1 2 port 1 contains 59H 01011001B Variations CLR bit51 Binary Mode Source Mode Bytes 4 3...

Страница 297: ...g is set otherwise it is clear When subtracting signed integers the OV flag indicates a negative result when a negative value is subtracted from a positive value or a positive result when a positive v...

Страница 298: ...d WRjs CMP DRkd DRks Binary Mode Source Mode Bytes 3 2 States 5 4 Hex Code in Binary Mode A5 Encoding Source Mode Encoding Operation CMP DRkd DRks CMP Rm data Binary Mode Source Mode Bytes 4 3 States...

Страница 299: ...e A5 Encoding Source Mode Encoding Operation CMP DRk 0data16 CMP DRk 1data16 Binary Mode Source Mode Bytes 5 4 States 6 5 Encoding Hex Code in Binary Mode A5 Encoding Source Mode Encoding Operation CM...

Страница 300: ...Mode Source Mode Bytes 5 4 States 3 2 Encoding Hex Code in Binary Mode A5 Encoding Source Mode Encoding Operation CMP Rm dir16 CMP WRj dir16 Binary Mode Source Mode Bytes 5 4 States 4 3 Encoding Hex...

Страница 301: ...g Operation CMP Rm DRk CPL A Function Complement accumulator Description Logically complements each bit of the accumulator one s complement Clear bits are set and set bits are cleared Flags Example Th...

Страница 302: ...the output data latch not the input pin Flags Only for instructions with CY as the operand Example Port 1 contains 5BH 01011101B After executing the instruction sequence CPL P1 1 CPL P1 2 port 1 cont...

Страница 303: ...carry out of the lowest 4 bits propagated through all higher bits but it does not clear the CY flag otherwise If the CY flag is now set or if the upper four bits now exceed nine 1010XXXX 1111XXXX the...

Страница 304: ...iables can be incremented or decremented by adding 01H or 99H If the accumulator contains 30H representing the digits of 30 decimal then the instruction sequence ADD A 99H DA A leaves the CY flag set...

Страница 305: ...ry Mode Source Mode Bytes 1 1 States 1 1 Hex Code in Binary Mode Encoding Source Mode Encoding Operation DEC A A 1 DEC dir8 Binary Mode Source Mode Bytes 2 2 States 2 2 If this instruction addresses a...

Страница 306: ...nd by 1 2 or 4 An original value of 00H underflows to 0FFH Flags Example Register 0 contains 7FH 01111111B After executing the instruction sequence DEC R0 1 register 0 contains 7EH Variations DEC Rm s...

Страница 307: ...esides the 8 bit remainder is stored in the lower byte of the word where Rmd resides For example Register 1 contains 251 0FBH or 11111011B and register 5 contains 18 12H or 00010010B After executing t...

Страница 308: ...d WRjs WRjd 2 remainder WRjd WRjs if dest jd 2 6 10 30 WRjd quotient WRjd WRjs For word operands dest src WRjd WRjs the 16 bit quotient is in WR jd 2 and the 16 bit remainder is in WRjd For example fo...

Страница 309: ...ding Source Mode Encoding Operation DIV A quotient A B B remainder A B DJNZ byte rel addr Function Decrement and jump if not zero Description Decrements the specified location by 1 and branches to the...

Страница 310: ...to 512 machine cycles with a single instruction The instruction sequence toggles P1 7 eight times causing four output pulses to appear at bit 7 of output Port 1 Each pulse lasts three states two for D...

Страница 311: ...truction Program execution continues with the instruction at this address The subroutine may therefore begin anywhere in the full 16 Mbyte memory space Flags Example The stack pointer contains 07H and...

Страница 312: ...order and 16 bits of the low order words of the PC with the second third and fourth instruction bytes The destination may be therefore be anywhere in the full 16 Mbyte memory space Flags Example The...

Страница 313: ...23H and 49H respectively After executing the instruction ERET the stack pointer contains 08H and program execution continues at location 012349H Binary Mode Source Mode Bytes 3 2 States 10 9 Hex Code...

Страница 314: ...INC A Binary Mode Source Mode Bytes 1 1 States 1 1 Hex Code in Binary Mode Encoding Source Mode Encoding Operation INC A A 1 INC dir8 Binary Mode Source Mode Bytes 2 2 States 2 2 If this instruction a...

Страница 315: ...ginal value of 0FFH overflows to 00H Flags Example Register 0 contains 7EH 011111110B After executing the instruction INC R0 1 register 0 contains 7FH Variations INC Rm short Binary Mode Source Mode B...

Страница 316: ...ormed an overflow of the low byte of the data pointer DPL from 0FFH to 00H increments the high byte of the data pointer DPH by one An overflow of the high byte DPH does not increment the high word of...

Страница 317: ...tains 11001010B and the accumulator contains 56 01010110B After the instruction sequence JB P1 2 LABEL1 JB ACC 2 LABEL2 program execution continues at label LABEL2 Variations JB bit51 rel Binary Mode...

Страница 318: ...e first byte of the next instruction Note When this instruction is used to test an output pin the value used as the original data is read from the output data latch not the input pin Flags Example The...

Страница 319: ...h the next instruction The branch destination is computed by adding the signed relative displacement in the second instruction byte to the PC after incrementing the PC twice Flags Example The CY flag...

Страница 320: ...tion JE LABEL1 program execution continues at label LABEL1 Binary Mode Source Mode Not Taken Taken Not Taken Taken Bytes 3 3 2 2 States 2 5 1 4 Hex Code in Binary Mode A5 Encoding Source Mode Encoding...

Страница 321: ...n If the Z flag or the CY flag is set branch to the address specified otherwise proceed with the next instruction The branch destination is computed by adding the signed relative displacement in the s...

Страница 322: ...tor contains 04H at the start this sequence execution jumps to LABEL2 Remember that AJMP is a two byte instruction so the jump instructions start at every other address Binary Mode Source Mode Bytes 1...

Страница 323: ...ode Not Taken Taken Not Taken Taken Bytes 3 3 3 3 States 2 5 2 5 Hex Code in Binary Mode Encoding Source Mode Encoding Operation JNB PC PC 3 IF bit51 0 THEN PC PC rel JNB bit rel Binary Mode Source Mo...

Страница 324: ...nd causes program execution to continue at label LABEL2 Binary Mode Source Mode Not Taken Taken Not Taken Taken Bytes 2 2 2 2 States 1 4 1 4 Hex Code in Binary Mode Encoding Source Mode Encoding Opera...

Страница 325: ...s computed by adding the signed relative displacement in the second instruction byte to the PC after incrementing the PC twice The accumulator is not modified Flags Example The accumulator contains 00...

Страница 326: ...ame value Binary Mode Source Mode Not Taken Taken Not Taken Taken Bytes 3 3 2 2 States 2 5 1 4 Hex Code in Binary Mode A5 Encoding Source Mode Encoding Operation JSG PC PC 2 IF N 0 AND N OV THEN PC PC...

Страница 327: ...the next instruction The branch destination is computed by adding the signed relative displacement in the second instruction byte to the PC after incrementing the PC twice Flags Example The instructio...

Страница 328: ...if the Z flag is set OR if the N flag and the OV flag have different values Binary Mode Source Mode Not Taken Taken Not Taken Taken Bytes 3 3 2 2 States 2 5 1 4 Hex Code in Binary Mode A5 Encoding So...

Страница 329: ...esult onto the stack low byte first The stack pointer is incremented by two The high and low bytes of the PC are then loaded respectively with the second and third bytes of the LCALL instruction Progr...

Страница 330: ...tional branch to the specified address by loading the high and low bytes of the PC respectively with the second and third instruction bytes The destination may therefore be anywhere in the 64 Kbyte me...

Страница 331: ...on Twenty four combinations of source and destination addressing modes are allowed Flags Example On chip RAM location 30H contains 40H on chip RAM location 40H contains 10H and input port 1 contains 1...

Страница 332: ...ng Operation MOV dir8 data MOV Ri data Binary Mode Source Mode Bytes 2 3 States 3 4 Hex Code in Binary Mode Encoding Source Mode A5 Encoding Operation MOV Ri data MOV Rn data Binary Mode Source Mode B...

Страница 333: ...e Source Mode Bytes 2 3 States 2 3 If this instruction addresses a port Px x 0 3 add 1 state Hex Code in Binary Mode Encoding Source Mode A5 Encoding Operation MOV dir8 Rn MOV Ri dir8 Binary Mode Sour...

Страница 334: ...is instruction addresses a port Px x 0 3 add 1 state Hex Code in Binary Mode Encoding Source Mode Encoding Operation MOV A dir8 MOV A Ri Binary Mode Source Mode Bytes 1 2 States 2 3 Hex Code in Binary...

Страница 335: ...Ri A Binary Mode Source Mode Bytes 1 2 States 3 4 Hex Code in Binary Mode Encoding Source Mode A5 Encoding Operation MOV Ri A MOV Rn A Binary Mode Source Mode Bytes 1 2 States 1 2 Hex Code in Binary...

Страница 336: ...V DRkd DRks Binary Mode Source Mode Bytes 3 2 States 3 2 Hex Code in Binary Mode A5 Encoding Source Mode Encoding Operation MOV DRkd DRks MOV Rm data Binary Mode Source Mode Bytes 4 3 States 3 2 Hex C...

Страница 337: ...de Source Mode Bytes 5 4 States 5 4 Encoding Hex Code in Binary Mode A5 Encoding Source Mode Encoding Operation MOV DRk 1data16 MOV Rm dir8 Binary Mode Source Mode Bytes 4 3 States 3 2 If this instruc...

Страница 338: ...6 5 Hex Code in Binary Mode A5 Encoding Source Mode Encoding Operation MOV DRk dir8 MOV Rm dir16 Binary Mode Source Mode Bytes 5 4 States 3 2 Encoding Hex Code in Binary Mode A5 Encoding Source Mode E...

Страница 339: ...inary Mode Source Mode Bytes 4 3 States 2 2 Encoding Hex Code in Binary Mode A5 Encoding Source Mode Encoding Operation MOV Rm WRj MOV Rm DRk Binary Mode Source Mode Bytes 4 3 States 4 3 Encoding Hex...

Страница 340: ...nary Mode A5 Encoding Source Mode Encoding Operation MOV WRj DRk MOV dir8 Rm Binary Mode Source Mode Bytes 4 3 States 4 3 If this instruction addresses a port Px x 0 3 add 1 state Hex Code in Binary M...

Страница 341: ...Mode Bytes 5 4 States 4 3 Encoding Hex Code in Binary Mode A5 Encoding Source Mode Encoding Operation MOV dir16 Rm MOV dir16 WRj Binary Mode Source Mode Bytes 5 4 States 5 4 Encoding Hex Code in Binar...

Страница 342: ...Mode A5 Encoding Source Mode Encoding Operation MOV WRj Rm MOV DRk Rm Binary Mode Source Mode Bytes 4 3 States 5 4 Encoding Hex Code in Binary Mode A5 Encoding Source Mode Encoding Operation MOV DRk R...

Страница 343: ...WRj MOV Rm WRj dis16 Binary Mode Source Mode Bytes 5 4 States 6 5 Encoding Hex Code in Binary Mode A5 Encoding Source Mode Encoding Operation MOV Rm WRj dis MOV WRj WRj dis16 Binary Mode Source Mode B...

Страница 344: ...7 Encoding Hex Code in Binary Mode A5 Encoding Source Mode Encoding Operation MOV WRj DRk dis MOV WRj dis16 Rm Binary Mode Source Mode Bytes 5 4 States 6 5 Encoding Hex Code in Binary Mode A5 Encoding...

Страница 345: ...Encoding Hex Code in Binary Mode A5 Encoding Source Mode Encoding Operation MOV DRk dis WRj MOV dest bit src bit Function Move bit data Description Copies the Boolean variable specified by the second...

Страница 346: ...0 3 add 2 states Hex Code in Binary Mode Encoding Source Mode Encoding Operation MOV bit51 CY MOV CY bit51 Binary Mode Source Mode Bytes 2 2 States 1 1 If this instruction addresses a port Px x 0 3 ad...

Страница 347: ...ointer DPTR with the specified 16 bit constant The high byte of the constant is loaded into the high byte of the data pointer DPH The low byte of the constant is loaded into the low byte of the data p...

Страница 348: ...ween 0 and 3 The following instruction sequence translates the value in the accumulator to one of four values defined by the DB define byte directive If the subroutine is called with the accumulator e...

Страница 349: ...nstruction MOVH DRk 1122H executes DRk contains 1122 7788H Variations MOVH DRk data16 Binary Mode Source Mode Bytes 5 4 States 3 2 Encoding Hex Code in Binary Mode A5 Encoding Source Mode Encoding Ope...

Страница 350: ...es an 8 bit address on port 0 Eight bits are sufficient for external I O expansion decoding or for a relatively small RAM array For larger arrays any port pins can be used to output higher address bit...

Страница 351: ...the instruction sequence MOVX A R1 MOVX R0 A the accumulator and external RAM location 12H contain 56H Variations MOVX A DPTR Binary Mode Source Mode Bytes 1 1 States 5 5 Hex Code in Binary Mode Enco...

Страница 352: ...f the 16 bit register is filled with zeros Flags Example Eight bit register Rm contains 055H 01010101B and 16 bit register WRj contains 0FFFFH 11111111 11111111B The instruction MOVZ WRj Rm moves the...

Страница 353: ...red in the following word register In this operation the OV flag is set if the product is greater than 0FFFFH otherwise it is cleared The CY flag is always cleared The N flag is set when the MSB of th...

Страница 354: ...the 16 bit product is left in the accumulator and the high byte is left in register B If the product is greater than 255 0FFH the OV flag is set otherwise it is clear The CY flag is always clear Flags...

Страница 355: ...dest src Function Logical OR for byte variables Description Performs the bitwise logical OR operation V between the specified variables storing the results in the destination operand The destination o...

Страница 356: ...r at run time After executing the instruction ORL P1 00110010B sets bits 5 4 and 1 of output Port 1 Variations ORL dir8 A Binary Mode Source Mode Bytes 2 2 States 2 2 If this instruction addresses a p...

Страница 357: ...Operation ORL A A V dir8 ORL A Ri Binary Mode Source Mode Bytes 1 2 States 2 3 Hex Code in Binary Mode Encoding Source Mode A5 Encoding Operation ORL A A V Ri ORL A Rn Binary Mode Source Mode Bytes 1...

Страница 358: ...WRjd WRjd V WRjs ORL Rm data Binary Mode Source Mode Bytes 4 3 States 3 2 Hex Code in Binary Mode A5 Encoding Source Mode Encoding Operation ORL Rm Rm V data ORL WRj data16 Binary Mode Source Mode By...

Страница 359: ...s 4 3 States 4 3 Hex Code in Binary Mode A5 Encoding Source Mode Encoding Operation ORL WRj WRj V dir8 ORL Rm dir16 Binary Mode Source Mode Bytes 5 4 States 3 2 Encoding Hex Code in Binary Mode A5 Enc...

Страница 360: ...coding Source Mode Encoding Operation ORL Rm Rm V DRk ORL CY src bit Function Logical OR for bit variables Description Sets the CY flag if the Boolean value is a logical 1 leaves the CY flag in its cu...

Страница 361: ...coding Source Mode Encoding Operation ORL CY CY V bit51 ORL CY bit51 Binary Mode Source Mode Bytes 2 2 States 1 1 If this instruction addresses a port Px x 0 3 add 1 state Hex Code in Binary Mode Enco...

Страница 362: ...rred to the newly addressed location which can be 8 bit or 16 bit Flags Example The stack pointer contains 32H and on chip RAM locations 30H through 32H contain 01H 23H and 20H respectively After exec...

Страница 363: ...POP Rm SP SP SP 1 POP WRj Binary Mode Source Mode Bytes 3 2 States 5 4 Hex Code in Binary Mode A5 Encoding Source Mode Encoding Operation POP SP SP 1 WRj SP SP SP 1 POP DRk Binary Mode Source Mode Byt...

Страница 364: ...H After executing the instruction sequence PUSH DPL PUSH DPH the stack pointer contains 0BH and on chip RAM locations 0AH and 0BH contain 01H and 23H respectively Variations PUSH dir8 Binary Mode Sour...

Страница 365: ...H Rm Binary Mode Source Mode Bytes 3 2 States 4 3 Hex Code in Binary Mode A5 Encoding Source Mode Encoding Operation PUSH SP SP 1 SP Rm PUSH WRj Binary Mode Source Mode Bytes 3 2 States 5 4 Hex Code i...

Страница 366: ...nues at the resulting address which normally is the instruction immediately following ACALL or LCALL Flags Example The stack pointer contains 0BH and on chip RAM locations 0AH and 0BH contain 01H and...

Страница 367: ...ected For either value of INTR hardware restores the interrupt logic to accept additional interrupts at the same priority level as the one just processed Program execution continues at the return addr...

Страница 368: ...After executing the instruction RL A the accumulator contains 8BH 10001011B the CY flag is unaffected Binary Mode Source Mode Bytes 1 1 States 1 1 Hex Code in Binary Mode Encoding Source Mode Encodin...

Страница 369: ...A 0 CY CY A 7 RR A Function Rotate accumulator right Description Rotates the 8 or 16 bits in the accumulator one bit to the right Bit 0 is moved into the bit 7 or 15 position Flags Example The accumul...

Страница 370: ...62 01100010B and the CY flag is set Binary Mode Source Mode Bytes 1 1 States 1 1 Hex Code in Binary Mode Encoding Source Mode Encoding Operation RRC A a A a 1 A 7 CY CY A 0 SETB bit Function Set bit...

Страница 371: ...his instruction addresses a port Px x 0 3 add 2 states Encoding Hex Code in Binary Mode A5 Encoding Source Mode Encoding Operation SETB bit 1 SJMP rel Function Short jump Description Program control b...

Страница 372: ...would be a one instruction infinite loop Binary Mode Source Mode Bytes 2 2 States 4 4 Hex Code in Binary Mode Encoding Source Mode Encoding Operation SJMP PC PC 2 PC PC rel SLL src Function Shift log...

Страница 373: ...ription Shifts the specified variable to the arithmetic right by 1 bit The MSB is unchanged The bit shifted out LSB is stored in the CY bit Flags Example Register 1 contains 0C5H 11000101B After execu...

Страница 374: ...the right by 1 bit replacing the MSB with a zero The bit shifted out LSB is stored in the CY bit Flags Example Register 1 contains 0C5H 11000101B After executing the instruction SRL register 1 Regist...

Страница 375: ...is subtracted from a positive value or a positive result when a positive number is subtracted from a negative number Bit 7 in this description refers to the most significant byte of the operand 8 16 o...

Страница 376: ...DRkd DRks Binary Mode Source Mode Bytes 3 2 States 5 4 Hex Code in Binary Mode A5 Encoding Source Mode Encoding Operation SUB DRkd DRkd DRks SUB Rm data Binary Mode Source Mode Bytes 4 3 States 3 2 H...

Страница 377: ...Mode Bytes 4 3 States 3 2 If this instruction addresses a port Px x 0 3 add 1 state Hex Code in Binary Mode A5 Encoding Source Mode Encoding Operation SUB Rm Rm dir8 SUB WRj dir8 Binary Mode Source M...

Страница 378: ...ding Hex Code in Binary Mode A5 Encoding Source Mode Encoding Operation SUB WRj WRj dir16 SUB Rm WRj Binary Mode Source Mode Bytes 4 3 States 3 2 Encoding Hex Code in Binary Mode A5 Encoding Source Mo...

Страница 379: ...gative number produced when a negative value is subtracted from a positive value or a positive result when a positive number is subtracted from a negative number Bit 6 and bit 7 in this description re...

Страница 380: ...e Encoding Source Mode Encoding Operation SUBB A A CY dir8 SUBB A Ri Binary Mode Source Mode Bytes 1 2 States 2 3 Hex Code in Binary Mode Encoding Source Mode A5 Encoding Operation SUBB A A CY Ri SUBB...

Страница 381: ...y Mode Encoding Source Mode Encoding Operation SWAP A 3 0 A 7 4 TRAP Function Causes interrupt call Description Causes an interrupt call that is vectored through location 0FF007BH The operation of thi...

Страница 382: ...ariable The source destination operand can use register direct or register indirect addressing Flags Example R0 contains the address 20H the accumulator contains 3FH 00111111B and on chip RAM location...

Страница 383: ...he low nibble of the accumulator bits 3 0 generally representing a hexadecimal or BCD digit with that of the on chip RAM location indirectly addressed by the specified register Does not affect the hig...

Страница 384: ...or immediate data Note When this instruction is used to modify an output port the value used as the original port data is read from the output data latch not the input pins Flags Example The accumula...

Страница 385: ...dir8 dir8 data XRL A data Binary Mode Source Mode Bytes 2 2 States 1 1 Hex Code in Binary Mode Encoding Source Mode Encoding Operation XRL A A data XRL A dir8 Binary Mode Source Mode Bytes 2 2 States...

Страница 386: ...de Encoding Source Mode A5 Encoding Operation XRL A A Rn XRL Rmd Rms Binary Mode Source Mode Bytes 3 2 States 2 1 Hex Code in Binary Mode A5 Encoding Source Mode Encoding Operation XRL Rmd Rmd Rms XRL...

Страница 387: ...Source Mode Encoding Operation XRL WRj WRj data16 XRL Rm dir8 Binary Mode Source Mode Bytes 4 3 States 3 2 If this instruction addresses a port Px x 0 3 add 1 state Hex Code in Binary Mode A5 Encoding...

Страница 388: ...m dir16 XRL WRj dir16 Binary Mode Source Mode Bytes 5 4 States 4 3 Encoding Hex Code in Binary Mode A5 Encoding Source Mode Encoding Operation XRL WRj WRj dir16 XRL Rm Wrj Binary Mode Source Mode Byte...

Страница 389: ...TION SET REFERENCE XRL Rm Drk Binary Mode Source Mode Bytes 4 3 States 4 3 Encoding Hex Code In Binary Mode A5 Encoding Source Mode Encoding Operation XRL Rm Rm DRk 0 1 1 0 1 1 1 0 u u u u 1 0 1 1 s s...

Страница 390: ......

Страница 391: ...B Signal Descriptions...

Страница 392: ......

Страница 393: ...RD WR and PSEN pins for exter nal memory accesses Figure B 1 8XC251SA SB SP SQ 44 pin PLCC Package AD4 P0 4 AD5 P0 5 AD6 P0 6 AD7 P0 7 EA VPP VSS2 ALE PROG PSEN A15 P2 7 A14 P2 6 A13 P2 5 P1 4 CEX1 P...

Страница 394: ...WAIT 8 7 AD7 P0 7 36 32 P1 7 CEX4 A17WCLK 9 8 A8 P2 0 24 21 P3 0 RXD 11 10 A9 P2 1 25 22 P3 1 TXD 13 11 A10 P2 2 26 23 P3 4 T0 16 14 A11 P2 3 27 24 P3 5 T1 17 15 A12 P2 4 28 25 A13 P2 5 29 26 Power G...

Страница 395: ...formation is available on lines A15 8 and AD7 0 An external latch can use ALE to demultiplex the address from the address data bus PROG The descriptions of A15 8 P2 7 0 and AD7 0 P0 7 0 are for the no...

Страница 396: ...0 P1 0 P1 1 P1 2 P1 5 3 P1 6 P1 7 I O Port 1 This is an 8 bit bidirectional I O port with internal pullups T2 T2EX ECI CEX2 0 CEX3 WAIT CEX4 A17 WCLK P2 7 0 I O Port 2 This is an 8 bit bidirectional...

Страница 397: ...smit Serial Data TXD outputs the shift clock in serial I O mode 0 and transmits serial data in serial I O modes 1 2 and 3 P3 1 VCC PWR Supply Voltage Connect this pin to the 5V supply voltage VCC2 PWR...

Страница 398: ...cillator frequency P1 7 CEX4 A17 WR O Write Write signal output to external memory Asserted for the memory address range specified by configuration byte UCONFIG0 bits RD1 0 Table B 3 Also see RD P3 6...

Страница 399: ...to all memory locations 128 Kbyte external memory 1 0 P1 7 CEX4 WCLK P3 7 only Asserted for all addresses Asserted for writes to all memory locations 64 Kbyte external memory One additional port pin...

Страница 400: ......

Страница 401: ...C Registers...

Страница 402: ......

Страница 403: ...Tables C 2 through C 6 list the SFRs by functional category Table C 7 lists the regis ters that make up the register file The remainder of the appendix contains descriptions of the SFRs arranged in al...

Страница 404: ...00000 PSW1 00000000 D7 C8 T2CON 00000000 T2MOD xxxxxx00 RCAP2L 00000000 RCAP2H 00000000 TL2 00000000 TH2 00000000 CF C0 C7 B8 IPL0 x0000000 SADEN 00000000 SPH 00000000 BF B0 P3 11111111 IPH0 x0000000...

Страница 405: ...H High Byte of DPTR S 83H DPXL Data Pointer Extended Low S 84H PCON Power Control S 87H IE0 Interrupt Enable Control 0 S A8H IPH0 Interrupt Priority Control High 0 S B7H IPL0 Interrupt Priority Contro...

Страница 406: ...0 Low Byte S 8AH TH0 Timer Counter 0 High Byte S 8CH TL1 Timer Counter 1 Low Byte S 8BH TH1 Timer Counter 1 High Byte S 8DH TL2 Timer Counter 2 Low Byte S CCH TH2 Timer Counter 2 High Byte S CDH TCON...

Страница 407: ...ow Byte S E9H CH PCA Timer Counter High Byte S F9H CCAP0L PCA Compare Capture Module 0 Low Byte S EAH CCAP1L PCA Compare Capture Module 1 Low Byte S EBH CCAP2L PCA Compare Capture Module 2 Low Byte S...

Страница 408: ...ack pointer SPH SPL 1 3 NOTE 1 The registers in the register file are normally accessed by mnemonic Depending on its loca tion a register can be addressed as a byte word and or dword See Figure 3 7 on...

Страница 409: ...ce to R11 These instructions can use byte registers Rm m 0 15 interchangeably 7 0 Accumulator Contents Bit Number Bit Mnemonic Function 7 0 ACC 7 0 Accumulator B Address F0H Reset State 0000 0000B B R...

Страница 410: ...re Registers These five register pairs store the 16 bit comparison value or captured value for the corresponding compare capture modules In the PWM mode the low byte register controls the duty cycle o...

Страница 411: ...high speed output pulse width modulation and watchdog timer modes 5 CAPPx Capture Mode Positive CAPPx 1 enables the capture function with capture triggered by a positive edge on pin CEXx 4 CAPNx Capt...

Страница 412: ...be cleared only by software 6 CR PCA Timer Counter Run Control Bit Set and cleared by software to turn the PCA timer counter on and off 5 Reserved The value read from this bit is indeterminate Write a...

Страница 413: ...L 1 disables the PCA timer counter during idle mode CIDL 0 allows the PCA timer counter to run during idle mode 6 WDTE Watchdog Timer Enable WDTE 1 enables the watchdog timer output on PCA module 4 WD...

Страница 414: ...Bit Number Bit Mnemonic Function 7 0 DPH 7 0 Data Pointer High Bits 8 15 of the extended data pointer DPX DR56 DPL Address S 82H Reset State 0000 0000B Data Pointer Low DPL provides SFR access to reg...

Страница 415: ...location 57 also named DPXL Location 57 is the lower byte of the upper word of the extended data pointer DPX DR56 whose lower word is the 16 bit data pointer DPTR See also DPH and DPL 7 0 DPXL Conten...

Страница 416: ...0 6 Clearing this bit disables all interrupts except the TRAP interrupt which is always enabled 6 EC PCA Interrupt Enable Setting this bit enables the PCA interrupt 5 ET2 Timer 2 Overflow Interrupt E...

Страница 417: ...0 4 IPH0 3 IPH0 2 IPH0 1 IPH0 0 Bit Number Bit Mnemonic Function 7 Reserved The value read from this bit is indeterminate Write a zero to this bit 6 IPH0 6 PCA Interrupt Priority Bit High 5 IPH0 5 Tim...

Страница 418: ...0 6 IPL0 5 IPL0 4 IPL0 3 IPL0 2 IPL0 1 IPL0 0 Bit Number Bit Mnemonic Function 7 Reserved The value read from this bit is indeterminate Write a zero to this bit 6 IPL0 6 PCA Interrupt Priority Bit Low...

Страница 419: ...e former contents of P0 are lost 7 0 P0 Contents Bit Number Bit Mnemonic Function 7 0 P0 7 0 Port 0 Register Write data to be driven onto the port 0 pins to these bits P1 Address S 90H Reset State 111...

Страница 420: ...Bit Number Bit Mnemonic Function 7 0 P2 7 0 Port 2 Register Write data to be driven onto the port 2 pins to these bits P3 Address S B0H Reset State 1111 1111B Port 3 P3 is the SFR that contains data t...

Страница 421: ...CON 7 are to the SM0 bit See Figure 10 2 on page 10 3 5 Reserved The value read from this bit is indeterminate Write a zero to this bit 4 POF Power Off Flag Set by hardware as VCC rises above 3 V to i...

Страница 422: ...addition or a borrow into bit 3 from subtraction Otherwise it is cleared This flag is useful for BCD arithmetic see Table 5 10 on page 5 17 5 F0 Flag 0 This general purpose flag is available to the us...

Страница 423: ...0 and 1 Identical to the RS1 0 bits in the PSW register 2 OV Overflow Flag Identical to the OV bit in the PSW register 1 Z Zero Flag This flag is set if the result of the last logical or arithmetic op...

Страница 424: ...2 SADDR Address S A9H Reset State 0000 0000B Slave Individual Address Register SADDR contains the device s individual address for multiprocessor communication 7 0 Slave Individual Address Bit Number B...

Страница 425: ...tiprocessor communication 7 0 Mask for SADDR Bit Number Bit Mnemonic Function 7 0 SADEN 7 0 SBUF Address S 99H Reset State XXXX XXXXB Serial Data Buffer Writing to SBUF loads the transmit buffer of th...

Страница 426: ...ial port operating mode SM0 SM1 Mode Description Baud Rate 0 0 0 Shift register FOSC 12 0 1 1 8 bit UART Variable 1 0 2 9 bit UART FOSC 32 or FOSC 64 1 1 3 9 bit UART Variable Select by programming th...

Страница 427: ...ta bit of a frame has been received Cleared by software SP Address S 81H Reset State 0000 0111B Stack Pointer SP provides SFR access to location 63 in the register file also named SP SP is the lowest...

Страница 428: ...d stack pointer SPX The extended stack pointer points to the current top of stack When a byte is saved PUSHed on the stack SPX is incremented and then the byte is written to the top of stack When a by...

Страница 429: ...l port modes 1 and 3 4 TCLK Transmit Clock Bit Selects timer 2 overflow pulses TCLK 1 or timer 1 overflow pulses TCLK 0 as the baud rate generator for serial port modes 1 and 3 3 EXEN2 Timer 2 Externa...

Страница 430: ...k out enable bits for timer 2 7 0 T2OE DCEN Bit Number Bit Mnemonic Function 7 2 Reserved The values read from these bits are indeterminate Write zeros to these bits 1 T2OE Timer 2 Output Enable Bit I...

Страница 431: ...re when the processor vectors to the interrupt routine 4 TR0 Timer 0 Run Control Bit Set cleared by software to turn timer 1 on off 3 IE1 Interrupt 1 Flag Set by hardware when an external interrupt is...

Страница 432: ...ect M11 M01 0 0 Mode 0 8 bit timer counter TH1 with 5 bit prescalar TL1 0 1 Mode 1 16 bit timer counter 1 0 Mode 2 8 bit auto reload timer counter TL1 Reloaded from TH1 at overflow 1 1 Mode 3 Timer 1...

Страница 433: ...Function 7 0 TH0 7 0 TL0 7 0 High byte of the timer 0 timer register Low byte of the timer 0 timer register TH1 TL1 Address TH1 S 8DH TL1 S 8BH Reset State 0000 0000B TH1 TL1 Timer Registers These reg...

Страница 434: ...N Address S A7H Reset State XXXX XX00B Wait State Control Register Use this register to enable the real time wait state input signal and or the wait state output clock 7 0 RTWCE RTWE Bit Number Bit Mn...

Страница 435: ...the WDTRST register clears and enables the hardware WDT The WDTRST register is a write only register Attempts to read it return FFH The WDT itself is not read or write accessible See section 8 7 Watch...

Страница 436: ......

Страница 437: ...Glossary...

Страница 438: ......

Страница 439: ...A register or storage location that forms the result of an arithmetic or logical operation addr11 An 11 bit destination address The destination can be anywhere in the same 2 Kbyte block of memory as t...

Страница 440: ...51 microcontroller bit A binary digit bit operand An addressable bit in the MCS 251 architecture bit51 An addressable bit in the MCS 51 architecture byte Any 8 bit unit of data clear The term clear r...

Страница 441: ...ge high to low transition a rising edge low to high transition or a rising or falling edge of an input signal as the assertion of that signal See also level triggered encryption array An array of key...

Страница 442: ...es a high level logic one or a low level logic zero of an input signal as the assertion of that signal See also edge triggered LSB Least significant bit of a byte or least significant byte of a word m...

Страница 443: ...8XC251SA SB SP SQ peripherals operate This is equal to six state times program memory A part of memory where instructions can be stored for fetching and execution powerdown mode The power conservation...

Страница 444: ...e that is selected by a configuration bit In source mode an MCS 251 microcontroller can execute recompiled source code written for an MCS 51 microcontroller In source mode the MCS 251 microcontroller...

Страница 445: ...mprises two contiguous bytes wraparound The result of interpreting an address whose hexadecimal expression uses more bits than the number of available address lines Wraparound ignores the upper addres...

Страница 446: ......

Страница 447: ...Index...

Страница 448: ......

Страница 449: ...lowing reset 11 7 idle mode 12 4 programming and verifying nonvolatile memory 14 3 ANL instruction 5 9 5 11 for bits A 23 ANL instruction 5 11 for bits A 23 Arithmetic instructions 5 8 5 9 table of A...

Страница 450: ...bus cycles 13 15 programming and verifying 14 1 UCONFIG0 table 4 6 UCONFIG1 table 4 7 Control instructions 5 1 5 12 5 16 addressing modes 5 12 5 13 table of A 24 Core 2 4 SFRs 3 18 C 3 CPL instruction...

Страница 451: ...13 1 External RAM example 13 26 exiting idle mode 12 5 F F0 flag 5 18 C 20 FaxBack service 1 7 1 8 Flash memory example 13 18 13 20 13 30 G Given address See Serial I O port Ground bounce 11 2 H Hard...

Страница 452: ...on A 24 JMP instruction A 24 JNB instruction 5 14 A 24 JNC instruction A 24 JNE instruction A 24 JNZ instruction A 24 JSG instruction A 25 JSGE instruction A 25 JSL instruction A 24 JSLE instruction A...

Страница 453: ...mode 4 15 source mode 4 15 See also Binary and source modes ORL instruction 5 9 5 11 for bits A 23 ORL instruction 5 11 for bits A 23 Oscillator 2 6 at startup 11 7 during reset 11 5 on chip 11 3 ONCE...

Страница 454: ...ditional jumps 5 14 effects of instructions on flags 5 17 PSW1 A 26 Pullups 7 8 ports 1 2 3 7 6 Pulse width measurements 8 10 PUSH instruction 3 15 5 10 A 22 Q Quick pulse algorithm 14 1 R RCAP2H RCAP...

Страница 455: ...0 10 baud rate generator 8 8 baud rate mode 0 10 4 10 10 baud rate modes 1 2 3 10 6 10 10 10 14 broadcast address 10 9 data frame modes 1 2 3 10 6 framing bit error detection 10 7 full duplex 10 6 giv...

Страница 456: ...k out mode 8 14 interrupt 8 11 mode select 8 15 Timer counters 8 1 8 17 external input sampling 8 3 internal clock 8 3 interrupts 8 1 overview 8 1 8 3 registers 8 2 SFRs 3 19 C 4 signal descriptions 8...

Страница 457: ...2 WCON 3 17 13 11 C 2 C 3 C 32 WDTRST 3 17 3 19 8 2 8 16 C 2 C 4 C 33 World Wide Web 1 7 WR 7 1 described 13 2 X XALE bit 4 13 XCH instruction 5 10 A 22 XCHD instruction 5 10 A 22 XRL instruction 5 9...

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