ST72361 datasheet(219/224 Pages) STMICROELECTRONICS

219 / 224 page

ST72361

219/224

IMPORTANT NOTES (Cont’d)

software sequence is given for both cases (global

interrupt disabled/enabled).

Case 1: Writing to PxOR or PxDDR with Global In-

terrupts Enabled:

LD A,#01

LD sema,A

; set the semaphore to '1'

LD A,PFDR

AND A,#02

LD X,A

; store the level before writing to

PxOR/PxDDR

LD A,#$90

LD PFDDR,A ; Write to 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,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 In-

terrupts Disabled:

SIM

; set the interrupt mask

LD A,PFDR

AND A,#$02

LD X,A

; store the level before writing to

PxOR/PxDDR

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

RIM

; reset the interrupt mask

LD A,sema ; check the semaphore status

CP A,#$01

jrne OUT

call call_routine; call the interrupt routine

RIM

OUT:

RIM

JP while_loop

.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

16.1.4 Unexpected Reset Fetch

If an interrupt request occurs while a "POP CC" in-

struction is executed, the interrupt controller does

not recognise the source of the interrupt and, by

default, passes the RESET vector address to the

CPU.

Workaround

To solve this issue, a "POP CC" instruction must

always be preceded by a "SIM" instruction.

ST72361 Datasheet(PDF) 219 Page - STMicroelectronics

ST72361 Datasheet(HTML) 219 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL