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PICBASIC assembler interrupt handling ?

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nebisman

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picbasic interrupts

Hi friends:


Can anybody show me a complete example of assembler level INTERRUPT handling in PIC BASIC PRO.


(It would be great if the example was with the USART RX interrupt, but any example is very grateful)

thanks in advance
Nebisman
 

dpechman

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pic asm interrupt handler

' Interrupts in assembly language
' Turn LED on. Interrupt on PORTB.0 (INTE) turns LED off.
' Program waits .5 seconds and turns LED back on.

led var PORTB.7

wsave var byte $20 system
'wsave1 var byte $a0 system ' Necessary for devices with RAM in bank1
'wsave2 var byte $120 system ' Necessary for devices with RAM in bank2
'wsave3 var byte $1a0 system ' Necessary for devices with RAM in bank3
ssave var byte bank0 system
psave var byte bank0 system


Goto start ' Skip around interrupt handler

' Define interrupt handler
define INTHAND myint

' Assembly language interrupt handler
asm

; Save W, STATUS and PCLATH registers, if not done previously
myint movwf wsave
swapf STATUS, W
clrf STATUS
movwf ssave
movf PCLATH, W
movwf psave

; Insert interrupt code here
; Save and restore FSR and any other registers used

bcf _led ; If interrupt, turn off LED
bcf INTCON, 1 ; Clear interrupt flag

; Restore saved registers
movf psave, W
movwf PCLATH
swapf ssave, W
movwf STATUS
swapf wsave, F
swapf wsave, W

retfie ; Return from interrupt

endasm


start: TRISB = $7f ' LED out, rest in
OPTION_REG = $7f ' Enable PORTB pullups

INTCON = $90 ' Enable INTE interrupt

led = 1 ' Turn LED on

loop: If led = 1 Then loop ' Wait here while LED is still on
' If we get here, LED is off
Pause 500 ' Wait .5 seconds
Goto start ' Start over (turn LED back on)
 

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