On Interrupt question

[peu]

Hi, im trying to understand how to use ON INTERRUPT, so I created this little program:

@ device pic16F628A, intrc_osc_noclkout, wdt_on, mclr_off, protect_off
DEFINE OSC 4

trisb   =%00110000
trisa   =%00000000
'ansel   =%00000001  
cmcon   =%00000111  'Comparators Off
vrcon   =%00000000
intcon  =%10101000  'interrupts enable    
OPTION_REG =%01010001     

but1    var trisb.4
but2    var trisb.5
ledwork var trisa.0
led1    var trisa.1
led2    var trisa.2
led3    var trisa.3
rs      var trisa.5


conta   var byte


on interrupt goto interrupcion

;SerOut rs,2,[10,13]
;SerOut rs,2,["inicio"]
;SerOut rs,2,[10,13]

enable
loop:

;disable
;SerOut rs,2,[10,13]
;SerOut rs,2,["Loop"]
;SerOut rs,2,[10,13]
;enable

for conta=0 to 255 step 16  'working led rise routine
    pwm ledwork, conta, 10  
next conta
high ledwork

for conta =0 to 100
    pause 10
next conta

low led1    'set status buttons leds off
low led2
low led3

for conta=0 to 255 step 16  'Fall routine
    pwm ledwork, 255-conta, 10 
next conta
low ledwork

for conta =0 to 100
    pause 10
next conta

low led1   'set button status leds off
low led2
low led3

goto loop

end
disable 
interrupcion:
;SerOut rs,2,[10,13]
;SerOut rs,2,["Interrupt"]
;SerOut rs,2,[10,13]
    intcon.0=0
    intcon.1=0
    intcon.2=0
        if but1=1 then
            but1=0
            high led1
        endif
        if but2=1 then
            but2=0
            high led2
        endif
high led3   
    resume
enable

The idea is to trigger an interrupt when any of the buttons (but1 & but2) are pressed, to show the status a led (led1 & led2) is turned on for a second and off again. led3 is used as a way to know an interruption has been triggered.

To simulate a real loop the "payload" of the program is a PWM pulse on ledwork

There are serouts all over the place, but since I cant make the basic version to work, these are commented out.


IMHO this program should work, but it doesn't. Could someone guide me in the right direction to fully understand how this should work?

Thanks!

[mister_e]

begin by changing this

but1    var trisb.4
but2    var trisb.5
ledwork var trisa.0
led1    var trisa.1
led2    var trisa.2
led3    var trisa.3
rs      var trisa.5

to

but1    var PORTB.4
but2    var PORTB.5
ledwork var PORTB.0
led1    var PORTB.1
led2    var PORTB.2
led3    var PORTB.3
rs      var PORTB.5

Let's see what happen now. i didn't go deeper than this.. for now

[peu]

I changed as you suggested but corrected the ports, I guess this is what you meant

but1    var PORTB.4
but2    var PORTB.5
ledwork var PORTA.0
led1    var PORTA.1
led2    var PORTA.2
led3    var PORTA.3
rs      var PORTA.5

And before the loop starts I added:

porta=0
portb=0


Now I can see the led1/led2 trigger after pressing for about a second, but the generic interrupt led3 is ON all the time which indicates me that the interrupt is being triggered constantly, regardless of the button presses.

Any idea?


Thanks


Pablo

[peu]

Im still puzzled by this, I know I must be near, but Im missing the finish line by a byte or two



Thanks, help is appreciated

[sougata]

Hi,

You are turning on the LED3 in the interrupt routine and turning it off in the main loop. So technically it should work. Now consider this :

Your buttons are not debounced so it may quite happen that another rising edge is setting up your interrupt. Since you have the buttons pressed while in interrupt you are being able to detect it and light led1 and led2.

So introduce a pause inside your interrupt after turning on the LEDs and as soon as you inside the interrupt release the button. Then while getting out clear the interrupt flags. This might solve your problem.

Regards

Sougata

[peu]

Hi,

You are turning on the LED3 in the interrupt routine and turning it off in the main loop. So technically it should work. Now consider this :

Your buttons are not debounced so it may quite happen that another rising edge is setting up your interrupt. Since you have the buttons pressed while in interrupt you are being able to detect it and light led1 and led2.

So introduce a pause inside your interrupt after turning on the LEDs and as soon as you inside the interrupt release the button. Then while getting out clear the interrupt flags. This might solve your problem.

Regards

Sougata

Hi Sougata,

If I enter any pause in the interrupt routine (I just tried it) I severelly impair the PWM loops, and this is another indication that the interrupt is being triggered constantly.

Here is the schematic:




Thanks


Pablo