DT Instant Interrupts - Clarification?

[Aussie Barry]

Hi All,

I am pleased to announce that the external interrupt routine is now working properly. Thank you to all who have helped me resolve my problems - much appreciated

To aid in my PCB layout I would like to move my ADC channels to AN1 and AN2. This will mean that I need to alter the type of interrupt from an external interrupt on GP2 to a Change on Interrupt on GP4. To do this I have changed the Interrupt Handler in DT_INST-14 from INT_INT to GPC_INT, Enable GPC_INT and enabled bit 4 of the Interrupt-On-Change GPIO Register (ie IOC.4=1). My interrupt switch is set up with a 10k pull-up resistor from GP4 to +5V and a momentary action switch from GP4 to 0V. The code compiles without error but the change on interrupt function does not work in "the real world".

I would have thought this was a pretty straight forward change but I am obviously missing something important. Would someone please direct me to where I have gone wrong?

Cheers
Barry

[HenrikOlsson]

Hi Barry,
In your latest attached code you have the line

ANSEL = %01011010       ' Set Fosc/16

Which sets GPIO.4/AN3 to analog mode. Try changing it to digital if you haven't already done that.

[Aussie Barry]

Hi Henrik,

Yes, I had already changed the ANSEL register
I had changed the TRISIO register too.
Attached is my full code listing for reference.

Now what? I am sure it is only something simple but I just can't figure it out...PICSprayer.bas

Cheers
Barry

[mackrackit]

[ code] remove the spaces in the brackets [ /code]

 remove the spaces in the brackets

It will save folks from having to download your code to look at it.

[cncmachineguy]

Unless I am not following your changes right, It seems in your ISR you are still waiting while gpio.2 is high. since that is now an analog input (I think) it might just be zooming right through the ISR making it look as though it was never called.

[Aussie Barry]

Yes, it was the GPOI.2 statement in the ISR that was causing the problem.
All fixed now

This is a Code Space Test

Hey, I even got the code space thing happening - I'm on fire!!!

Thanks for all your help guys - really appreciate it.
I will post details of the final project once it is all up and running - code, circuit diagram, PCB and some pretty pictures of the finished product.

Cheers
Barry

[retepsnikrep]

Just continuing on from this thread i have my own question about DT Interrupts for the 12F683.

Having looked at the example given by darrell for the generic timer the code below seems unecessary if we know what the values are for the prescaler etc?

;---[TMR1 reload - interrupt handler]-----------------------------------------
ASM ; Calculate Timer Reload Constant
ReloadInst = 8; # of Intructions used to reload timer
if ((Prescaler == 1)||(Prescaler == 2)||(Prescaler == 4)||(Prescaler == 8))
MaxCount = 65536 + (ReloadInst / Prescaler)
TimerReload = MaxCount - (OSC*1000000/4/Prescaler/Freq)
if ((TimerReload < 0) || (TimerReload > (65535-ReloadInst)))
error Invalid Timer Values - check "OSC", "Freq" and "Prescaler"
endif
else
error Invalid Prescaler
endif
ENDASM

Do we need this error checking if we know and are happy with osc/prescaler/freq etc or am i missing something else. It looks like it might take a fair bit of code space?

[mister_e]

That snip perform calculations at compilation time and doesn't take ANY codespace. 'course you can remove it. It's there for convenience and ease of use.