257
CHAPTER 19 INTERRUPT FUNCTIONS
Preliminary User’s Manual U14581EJ3V0UM00
Figure 19-12. Interrupt Request Acknowledge Timing (Minimum Time)
Remark
1 clock: 1/f
CPU
(f
CPU
: CPU clock)
Figure 19-13. Interrupt Request Acknowledge Timing (Maximum Time)
Remark
1 clock: 1/f
CPU
(f
CPU
: CPU clock)
19.4.3 Software interrupt request acknowledge operation
A software interrupt request is acknowledged by BRK instruction execution. Software interrupts cannot be disabled.
If a software interrupt request is acknowledged, the contents are saved into the stacks in the order of the program
status word (PSW), then program counter (PC), the IE flag is reset (to 0), and the contents of the vector table (003EH,
003FH) are loaded into PC and branched.
Return from a software interrupt is possible with the RETB instruction.
Caution
Do not use the RETI instruction for returning from the software interrupt.
8 clocks
7 clocks
Instruction
Instruction
PSW and PC save,
jump to interrupt
servicing
Interrupt servicing
program
CPU processing
××
IF
(
××
PR = 1)
××
IF
(
××
PR = 0)
6 clocks
33 clocks
32 clocks
Instruction
Divide instruction
PSW and PC save,
jump to interrupt
servicing
Interrupt servicing
program
CPU processing
××
IF
(
××
PR = 1)
××
IF
(
××
PR = 0)
6 clocks
25 clocks
Summary of Contents for mPD780851
Page 2: ...2 Preliminary User s Manual U14581EJ3V0UM00 MEMO ...
Page 8: ...8 Preliminary User s Manual U14581EJ3V0UM00 MEMO ...
Page 12: ...12 Preliminary User s Manual U14581EJ3V0UM00 MEMO ...
Page 26: ...26 Preliminary User s Manual U14581EJ3V0UM00 MEMO ...
Page 46: ...46 Preliminary User s Manual U14581EJ3V0UM00 MEMO ...
Page 74: ...74 Preliminary User s Manual U14581EJ3V0UM00 MEMO ...
Page 90: ...90 Preliminary User s Manual U14581EJ3V0UM00 MEMO ...
Page 100: ...100 Preliminary User s Manual U14581EJ3V0UM00 MEMO ...
Page 136: ...136 Preliminary User s Manual U14581EJ3V0UM00 MEMO ...
Page 142: ...142 Preliminary User s Manual U14581EJ3V0UM00 MEMO ...
Page 186: ...186 Preliminary User s Manual U14581EJ3V0UM00 MEMO ...
Page 222: ...222 Preliminary User s Manual U14581EJ3V0UM00 MEMO ...
Page 230: ...230 Preliminary User s Manual U14581EJ3V0UM00 MEMO ...
Page 240: ...240 Preliminary User s Manual U14581EJ3V0UM00 MEMO ...
Page 262: ...262 Preliminary User s Manual U14581EJ3V0UM00 MEMO ...
Page 296: ...296 Preliminary User s Manual U14581EJ3V0UM00 MEMO ...
Page 304: ...304 Preliminary User s Manual U14581EJ3V0UM00 MEMO ...
Page 314: ...314 Preliminary User s Manual U14581EJ3V0UM00 MEMO ...