Post by thread:[PIC]: 18F2320 TMR0 Interrupt

Hi PICList, long time no problem, time to change that! :) Someone smack me, I have to be doing something absurd. I can't get the flippin' TMR0 interrupt to fire on the 18F2320. I can get the TMR0IF flag to trigger, I can poll it and see it happen, that works no problem, so I know the timer is running, and overflowing correctly. I just can't get the actual low_priority ISR to be called, could be a Hi-Tech C problem (my misuse of it most likely) so I'm not sure. I've tried simply setting TMR0IF and the interrupt still won't go off. I'm just trying to light a damn LED now when either ISR invokes. Here's my current code, quite simple: ----- SNIP ----- ----- SNIP ----- ----- SNIP ----- ----- SNIP ----- void main() { init(); // setup ports, registers, etc... initPWM(); // start PWM sequence initInterrupts(); // setup interrupt masks, etc RB4 = RB5 = 1; while(1); } void init() { IRCF2 = IRCF1 = IRCF0 = 1; // 8MHz SCS1 = 1; // Internal oscillator select ADCON1 = 0x0C; // Internal ref, 2-0 Analog TRISA = 0b00111111; // See pinout TRISB = 0b11001111; // See pinout TRISC = 0b10000000; // See pinout } void initPWM() { T0CON = 0b01000110; // internal, 8-bit, 1:128 prescalar TMR0H = TMR0L = 0; // clear TMR0 TMR0ON = 1; // turn on TMR0 } void initInterrupts() { IPEN = 1; // enable interrupt priorities TMR0IP = 0; // TMR0 is low priority TMR0IE = 1; // enable TRM0 interrupt TMR0IF = 0; // clear pending interrupts GIEL = 1; // enable low priority interrupts } void interrupt ISR() { RB4 = 0; } void interrupt low_priority ISR_LOW() { RB5 = 0; } ------ SNIP ------ ----- SNIP ----- ----- SNIP ----- ----- SNIP ----- This is my first venture into 18-series and interrupt priorities, so I'm hoping I'm missing something, but the datasheet simply says to set the priority, masking and enable low-priority interrupts and it should be working, which makes sense, yet nothing it happening. Suggestions are welcome! :) Thanks in advance, Nick Veys -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

On Thu, 26 Feb 2004, Nick Veys wrote: > void initInterrupts() { > IPEN = 1; // enable interrupt priorities > > TMR0IP = 0; // TMR0 is low priority > TMR0IE = 1; // enable TRM0 interrupt > TMR0IF = 0; // clear pending interrupts > > GIEL = 1; // enable low priority interrupts > } > This is my first venture into 18-series and interrupt priorities, so I'm > hoping I'm missing something, but the datasheet simply says to set the > priority, masking and enable low-priority interrupts and it should be > working, which makes sense, yet nothing it happening. You need to set GIEH. The datasheet is lacking, if not completely erroneous in this area. You might want to refer to the 18C family document for more details. 10.3.1.2 Low Priority Interrupts [ ... ] The GIE/GIEH bit's function has not changed in that it still enables/disables all interrupts, however, it is only cleared by hardware when servicing a high priority interrupt. -- John W. Temples, III -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

And viola, it's fixed. That's an annoying doc oversight, thanks for the tip! spam_OUTpiclistTakeThisOuTXARGS.COM wrote: {Quote hidden}> On Thu, 26 Feb 2004, Nick Veys wrote: > > >>void initInterrupts() { >> IPEN = 1; // enable interrupt priorities >> >> TMR0IP = 0; // TMR0 is low priority >> TMR0IE = 1; // enable TRM0 interrupt >> TMR0IF = 0; // clear pending interrupts >> >> GIEL = 1; // enable low priority interrupts >>} > > >>This is my first venture into 18-series and interrupt priorities, so I'm >>hoping I'm missing something, but the datasheet simply says to set the >>priority, masking and enable low-priority interrupts and it should be >>working, which makes sense, yet nothing it happening. > > > You need to set GIEH. The datasheet is lacking, if not completely > erroneous in this area. You might want to refer to the 18C family > document for more details. > > 10.3.1.2 Low Priority Interrupts > > [ ... ] > > The GIE/GIEH bit's function has not changed in that it still > enables/disables all interrupts, however, it is only cleared by > hardware when servicing a high priority interrupt. > > -- > John W. Temples, III > > -- > http://www.piclist.com hint: The list server can filter out subtopics > (like ads or off topics) for you. See http://www.piclist.com/#topics > -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics