38
CHAPTER 5 CPU
●
Carry flag (C)
This flag is set to "1" when a carry from bit 7 or a borrow to bit 7 occurs as the result of an operation.
Otherwise, the flag is set to "0". When a shift instruction is executed, the flag is set to the shift-out value.
Figure 5.1-6 shows how the carry flag is updated by a shift instruction.
Figure 5.1-6 Carry Flag Updated by Shift Instruction
■
Interrupt Acceptance Control Bits
●
Interrupt enable flag (I)
When this flag is set to "1", interrupts are enabled and accepted by the CPU. When this flag is set to "0",
interrupts are disabled and rejected by the CPU.
The initial value after a reset is "0".
The SETI and CLRI instructions set and clear the flag to "1" and "0", respectively.
●
Interrupt level bits (IL1, IL0)
These bits indicate the level of the interrupt currently accepted by the CPU.
The interrupt level is compared with the value of the interrupt level setting register (ILR0 to ILR5) that
corresponds to the interrupt request (IRQ0 to IRQ23) of each peripheral resource.
The CPU services an interrupt request only when its interrupt level is smaller than the value of these bits
with the interrupt enable flag set (CCR: I = 1). Table 5.1-3 lists interrupt level priorities. The initial value
after a reset is "11
B
".
The interrupt level bits (IL1, IL0) are usually "11
B
" with the CPU not servicing an interrupt (with the main
program running).
For details on interrupts, see 8.1 Interrupts.
• Left-shift (ROLC)
• Right-shift (RORC)
bit7
bit0
bit7
bit0
C
C
Table 5.1-3 Interrupt Levels
IL1
IL0
Interrupt Level
Priority
0
0
0
High
0
1
1
1
0
2
1
1
3
Low (No interrupt)
Summary of Contents for F2 MC-8FX Family
Page 2: ......
Page 4: ......
Page 34: ...20 CHAPTER 1 DESCRIPTION ...
Page 38: ...24 CHAPTER 2 HANDLING DEVICES ...
Page 39: ...25 CHAPTER 3 MEMORY SPACE This chapter describes memory space 3 1 Memory Space 3 2 Memory Map ...
Page 56: ...42 CHAPTER 5 CPU ...
Page 73: ...59 CHAPTER 6 CLOCK CONTROLLER ...
Page 96: ...82 CHAPTER 6 CLOCK CONTROLLER ...
Page 104: ...90 CHAPTER 7 RESET ...
Page 105: ...91 CHAPTER 8 INTERRUPTS This chapter explains the interrupts 8 1 Interrupts ...
Page 174: ...160 CHAPTER 10 TIMEBASE TIMER ...
Page 184: ...170 CHAPTER 10 TIMEBASE TIMER ...
Page 218: ...204 CHAPTER 13 WATCH PRESCALER ...
Page 257: ...243 CHAPTER 16 8 16 BIT COMPOSITE TIMER ...
Page 261: ...247 CHAPTER 16 8 16 BIT COMPOSITE TIMER ...
Page 288: ...274 CHAPTER 16 8 16 BIT COMPOSITE TIMER ...
Page 301: ...287 CHAPTER 17 16 BIT PPG TIMER ...
Page 316: ...302 CHAPTER 17 16 BIT PPG TIMER ...
Page 382: ...368 CHAPTER 21 UART SIO DEDICATED BAUD RATE GENERATOR ...
Page 390: ...376 CHAPTER 22 I2C ...
Page 395: ...381 CHAPTER 22 I2C ...
Page 399: ...385 CHAPTER 22 I2C ...
Page 430: ...416 CHAPTER 23 10 BIT A D CONVERTER ...
Page 476: ...462 CHAPTER 24 LCD CONTROLLER ...
Page 482: ...468 CHAPTER 25 LOW VOLTAGE DETECTION RESET CIRCUIT ...
Page 494: ...480 CHAPTER 26 CLOCK SUPERVISOR ...
Page 507: ...493 CHAPTER 27 REAL TIME CLOCK ...
Page 523: ...509 CHAPTER 27 REAL TIME CLOCK ...
Page 532: ...518 CHAPTER 27 REAL TIME CLOCK ...
Page 536: ...522 CHAPTER 28 256 KBIT FLASH MEMORY ...
Page 554: ...540 CHAPTER 28 256 KBIT FLASH MEMORY ...
Page 564: ...550 CHAPTER 29 EXAMPLE OF SERIAL PROGRAMMING CONNECTION ...
Page 595: ...581 INDEX INDEX The index follows on the next page This is listed in alphabetic order ...
Page 596: ...582 INDEX Index ...
Page 597: ...583 INDEX ...
Page 600: ...586 Pin Function Index ...
Page 602: ......