EXTENDED FUNCTION TIMER (EFT)
EXTENDED FUNCTION TIMER (Cont’d)
Note: A single access (read/write) to the SR regis-
ter at the beginning of the interrupt routine is the
first step needed to clear all the EFT interrupt
flags. In a second step, the lower bytes of the data
registers must be accessed if the corresponding
flag is set. It is not necessary to access the SR
register between these instructions, but it can
done.
; INTERRUPT ROUTINE EXAMPLE
push R234
; Save current page
spp #28
; Set EFT page
L6:
cp R254,#0
; while E0_SR is not cleared
jxz L7
tm R254,#128
; Check Input Capture 1 flag
jxz L2
; else go to next test
ld r1,R241
; Dummy read to clear IC1LR
; Insert your code here
L2:
tm R254,#16
; Check Input Capture 2 flag
jxz L3
; else go to next test
ld r1,R243
; Dummy read to clear IC2LR
; Insert your code here
L3:
tm R254,#64
; Check Input Compare 1 flag
jxz L4
; else go to next test
ld r1,R249
; Dummy read to clear OC1LR
; Insert your code here
L4:
tm R254,#8
; Check Input Compare 2 flag
jxz L5
; else go to next test
ld r1,R251
; Dummy read to clear OC1LR
; Insert your code here
L5:
tm R254,#32
; Check Input Overflow flag
jxz L6
; else go to next test
ld r1,R245
; Dummy read to clear Overflow flag
; Insert your code here
jx L6
L7:
pop R234
; Restore current page
iret
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