Re: 68hc12 TOVF interrupt problems ICC12

A couple of things to check:

I don't think that the TCRE bit in TSCR2 should be set since you are not
using the TC7 counter.
Since TC7 resets to zero I'm not sure what will happen. Probably the TCNT
counter will never overflow because
it's being reset by the TC7 compare.

For reference you don't need to use  TFLG2 |= 0x80. TFLG2 = 0x80 will work
fine.
Also interrupt handlers usually reenable interrupts automatically using an
RTI instruction.
I'm not familiar with ICC12 so this may not be true.
I know for IAR compilers the function is prefaced by the keyword
__interrupt to indicate the function should use RTI instead of RTS.
However when your interrupt handler is used somewhere the RTI instruction
must be called when it is finished.
You should never need to do an asm("cli") instruction in an interrupt
handler.
Lastly I don't use the fast clear bit TFFCA in TSCR1. Since you reset it
with TFLG2 = 0x80 it's not needed. Plus you not accessing TC7 anyway.
If  ICC12 has a mixed listing output, see what instructions are generated.

Good luck.

Arlin L. Pierce
Principal Software Engineer
Raytheon Company / Rancho Innovations




"hendersonmarv" <hendersonmarv@...>
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03/25/2009 07:33 AM
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Subject
[68HC12] 68hc12 TOVF interrupt problems ICC12









I'm trying to get the timer overflow interrupt working on the
hc12dp256b but so far I haven't had any luck.

The overflow interrupt is never generated in my program(used a breakpiont
in isr) and I can't find the logic error in my code.

Here is my work environment:
CHIP: hc12dp256
COMPILER: ICC12
DEBUGGER: NOICE

Here's the code that doesn't work

----------------------------------------------------------
#include <hcs12dp256.h>
#include <stdio.h>

#pragma interrup_handler TOVF_ISR() (isrs installed in vector table file)

int count

void main(void)
{
//setup
TFLG2|=0x80; //Clear interrupt flag
TSCR2 =0x8D; //Set timer frequency(250kHz), Enable TOVF int
TSCR1|=0x90; //enable timer and fast clear TOC7

asm("cli");

count=0;
while(count<3){
if(i%2000==0) printf("count: %d\n",count);
i++;
}

printf("count reached three\n");
}

void TOVF_ISR()
{
asm("cli"); //reenable interrupts
count++;
TFLG2|=0X80;
}
----------------------------------------------------------

Thanks to anyone who can help me out






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