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21-2
MSM66591/ML66592 User's Manual
Chapter 21 Bus Port Functions
21.2 External Memory Access
21.2.1 External Program Memory Access
The MSM66591 can access a maximum of 128K bytes (00000H–1FFFDH) of program
memory space using a 16-bit program counter and a 1-bit code segment register
(CSR). When the
EA
pin is low, external program memory is accessed to 00000H–
1FFFDH.
By using a 16-bit program counter and a 2-bit code segment register (CSR), the
ML66592 can access a maximum of 192K bytes (00000H–2FFFDH) of program
memory space internally and a maximum of 256K bytes (0000H–3FFDH) of program
memory space externally. When the
EA
pin is low, external program memory is ac-
cessed to 00000H–3FFFDH.
The Figure 21-1 shows the external program memory (ROM) connection example.
AD0–AD7 (P0_0–P0_7)
(P7_2) ALE
A8–A16 (P1_0–P1_7, P12_0)
(P7_3)
PSEN
O0–O7
A0–A7
A8–A16
OE
CE
MSM66591
External ROM (128K bytes MAX.)
Latch
Circuit
[Note]
Since in the ML66592 address 17 (A17) is output from the P12_1 pin, connect
the P12_1 pin to A17 of the external ROM. Up to 256K bytes can be accessed.
Figure 21-1 External ROM Connection Example (MSM66591)
21.2.2 External Program Memory Access Timing
Figures 21-2 and 21-3 show external program memory access timing.
The MSM66591/ML66592 have a function to insert a wait cycle when the external
memory access time is slow. (READY function: see 5.2). Use this function according to
the access time of the external memory required for use.
However, unlike access to the internal memory, one cycle is automatically inserted for
every one-byte-access to the external memory.
ROMRDY is a register to specify the number of cycles to be inserted in addition to the
above one cycle.
For actual AC characteristics, see Chapter 25, "Electrical Characteristics."
Содержание ML66592
Страница 1: ...MSM66591 ML66592 User s Manual CMOS 16 bit microcontroller FEUL66591 66592 01 Issue Date Mar 4 2002 ...
Страница 15: ...Contents 12 ...
Страница 17: ......
Страница 18: ...Overview Chapter 1 1 ...
Страница 19: ......
Страница 30: ...Description of Pins Chapter 2 2 ...
Страница 31: ......
Страница 44: ...CPU Architecture Chapter 3 3 ...
Страница 45: ......
Страница 101: ...3 56 MSM66591 ML66592User sManual Chapter 3 CPU Architecture ...
Страница 102: ...CPU Control Functions Chapter 4 4 ...
Страница 103: ......
Страница 111: ...4 8 MSM66591 ML66592User sManual Chapter 4 CPU Control Functions ...
Страница 112: ...Memory Control Functions Chapter 5 5 ...
Страница 113: ......
Страница 117: ...5 4 MSM66591 ML66592User sManual Chapter 5 Memory Control Functions ...
Страница 118: ...Port Functions Chapter 6 6 ...
Страница 119: ......
Страница 152: ...Output Pin Control Pin OE Chapter 7 7 ...
Страница 153: ......
Страница 155: ...7 2 MSM66591 ML66592User sManual Chapter 7 Output Pin Control Pin OE ...
Страница 156: ...Clock Generation Circuit Chapter 8 8 ...
Страница 157: ......
Страница 160: ...Time Base Counter TBC Chapter 9 9 ...
Страница 161: ......
Страница 164: ...Watchdog Timer WDT Chapter 10 10 ...
Страница 165: ......
Страница 170: ...Flexible Timer FTM Chapter 11 11 11 ...
Страница 171: ......
Страница 213: ...11 42 MSM66591 ML66592User sManual Chapter 11 Flexible Timer FTM ...
Страница 214: ...General Purpose 8 Bit Timer Function Chapter 12 12 ...
Страница 215: ......
Страница 223: ...12 8 MSM66591 ML66592User sManual Chapter 12 General Purpose 8 Bit Timer Function ...
Страница 224: ...PWM Functions Chapter 13 13 ...
Страница 225: ......
Страница 244: ...Baud Rate Generator Functions Chapter 14 14 ...
Страница 245: ......
Страница 263: ...14 18 MSM66591 ML66592User sManual Chapter 14 Baud Rate Generator Functions ...
Страница 264: ...Serial Port Functions Chapter 15 15 ...
Страница 265: ......
Страница 348: ...A D Converter Functions Chapter 16 16 ...
Страница 349: ......
Страница 381: ...16 32 MSM66591 ML66592User sManual Chapter 16 A D Converter Functions ...
Страница 382: ...Transition Detector Functions Chapter 17 17 ...
Страница 383: ......
Страница 387: ...17 4 MSM66591 ML66592User sManual Chapter 17 Transition Detector Functions ...
Страница 388: ...Peripheral Functions Chapter 18 18 ...
Страница 389: ......
Страница 392: ...External Interrupt Request Function Chapter 19 19 ...
Страница 393: ......
Страница 396: ...Interrupt Request Processing Function Chapter 20 20 ...
Страница 397: ......
Страница 407: ...20 10 MSM66591 ML66592User sManual Chapter 20 Interrupt Request Processing Function ...
Страница 408: ...Bus Port Functions Chapter 21 21 ...
Страница 409: ......
Страница 413: ...21 4 MSM66591 ML66592User sManual Chapter 21 Bus Port Functions ...
Страница 414: ...Expansion Port Chapter 22 22 ...
Страница 415: ......
Страница 420: ...Serial Port with FIFO SCI5 Chapter 23 23 ...
Страница 421: ......
Страница 431: ...23 10 MSM66591 ML66592User sManual Chapter 23 Serial Port with FIFO SCI5 ...
Страница 432: ...RAM Monitor Function Chapter 24 24 ...
Страница 433: ......
Страница 441: ...24 8 MSM66591 ML66592User sManual Chapter 24 RAM Monitor Function ...
Страница 442: ...25 Electrical Characteristics Chapter 25 ...
Страница 443: ......
Страница 458: ...Package Dimensions Chapter 26 26 ...
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Страница 461: ...26 2 MSM66591 ML66592User sManual Chapter 26 Package Dimensions ...
Страница 462: ...Revision History Chapter 27 27 ...
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Страница 465: ...27 2 MSM66591 ML66592User sManual Chapter 27 Revision History ...