ST72F324BJ STMICROELECTRONICS [STMicroelectronics], ST72F324BJ Datasheet - Page 181

• Manufacturer Part Number: ST72F324BJ
• Description: 8-bit MCU, 3.8 to 5.5 V operating range with 8 to 32 Kbyte Flash/ROM, 10-bit ADC, 4 timers, SPI, SCI
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

ST72324B
Case 1: Writing to PxOR or PxDDR with global interrupts enabled:
LD A,#01
LD sema,A; set the semaphore to '1'
LD A,PFDR
AND A,#02
LD
LD A,#$90
LD PFDDR,A ; Write to PFDDR
LD A,#$ff
LD
LD A,PFDR
AND A,#02
LD Y,A; store the level after writing to PxOR/PxDDR
LD A,X; check for falling edge
cp A,#02
jrne OUT
TNZ Y
jrne OUT
LD A,sema ; check the semaphore status if edge is detected
CP A,#01
jrne OUT
call call_routine ; call the interrupt routine
OUT:LD A,#00
LD sema,A
.call_routine ; entry to call_routine
PUSH A
PUSH X
PUSH CC
.ext1_rt ; entry to interrupt routine
LD A,#00
LD sema,A
IRET
Case 2: Writing to PxOR or PxDDR with global interrupts disabled:
SIM ; set the interrupt mask
LD A,PFDR
AND A,#$02
LD
LD A,#$90
LD PFDDR,A ; Write into PFDDR
LD A,#$ff
LD PFOR,A ; Write to PFOR
LD A,PFDR
AND A,#$02
LD Y,A ; store the level after writing to PxOR/PxDDR
LD A,X ; check for falling edge
cp A,#$02
jrne OUT
TNZ Y
jrne OUT
LD A,#$01
LD sema,A ; set the semaphore to '1' if edge is detected
X,A; store the level before writing to PxOR/PxDDR
PFOR,A ; Write to PFOR
X,A ; store the level before writing to PxOR/PxDDR
Known limitations
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