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Futureatwork
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| 18F452 int fast bug |
 Posted: Wed Jul 14, 2004 7:02 am |
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Just to confirm my findings, if I use this PIC I can not use any fast int or just EXT?
I need to write a tachometer application, two possibilities are the use of ccp1 or rb0 int.. with RB0 int fast the program crashes/resets.
If I switch to CCP1 will the bug happen? |
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Ttelmah
Guest
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| Re: 18F452 int fast bug |
| Posted: Wed Jul 14, 2004 7:06 am |
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| Futureatwork wrote: | Just to confirm my findings, if I use this PIC I can not use any fast int or just EXT?
I need to write a tachometer application, two possibilities are the use of ccp1 or rb0 int.. with RB0 int fast the program crashes/resets.
If I switch to CCP1 will the bug happen? |
If you are using the fast interrupt, it is _your_ responsibility to save and restore the registers in the interrupt handler routine. If the code is immediately crashing, this is probably the problem, and would apply to any interrupt used with the fast option.
Seperately, there is an issue with _old_ chips (it has been fixed for over a year), which can very occasionally cause a crash. You need to check the date code of your chip to see if this applies to you.
Best Wishes |
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Futureatwork
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| Posted: Wed Jul 14, 2004 7:17 am |
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It works for some time then it gets weird, timer2 interrupt change its interrupt rate(the led blinks very fast instead of 1s) or it crashes.
The code inside of the interrupt handler is just some MOVFF and reset timer1. |
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Futureatwork
Guest
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| Posted: Wed Jul 14, 2004 7:29 am |
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| Code: | .................... #int_ext
.................... void ext_isr(void) {
.................... if(bit_test(INTCON2,INTEDGE0)) { // rising edge detected
*
0460: BTFSS FF1.6
0462: BRA 048A
.................... setup_ccp1(CCP_OFF); // stop comparator so
0466: MOVLW B7
0468: ANDWF FB1,F
046A: CLRF FBD
046C: CLRF FBD
.................... output_high(PIN_C2); // we can set output high
046E: BSF F8B.2
.................... period=get_timer0(); set_timer0(0);
0478: MOVF FD6,W
047A: MOVFF FD7,03
047E: MOVWF xC1
0480: MOVFF 03,C2
0484: CLRF FD7
0486: CLRF FD6
.................... } else {
0488: BRA 04A4
.................... CCP_1=advance; // here we set advanve timing
048E: MOVFF C4,FBF
0492: MOVFF C3,FBE
.................... set_timer1(0); // clear timer to start from 0
0496: CLRF FCF
0498: CLRF FCE
.................... setup_ccp1(CCP_COMPARE_CLR_ON_MATCH); // here we go!
049A: MOVLW B7
049C: ANDWF FB1,F
049E: BSF F8B.2
04A0: MOVLW 09
04A2: MOVWF FBD
.................... }
.................... #asm btg INTCON2,INTEDGE0 #endasm
04A4: BTG FF1.6
.................... }
....................
04A6: BCF FF2.1
04A8: GOTO 006C |
With this I expect to extend for some time the pulse received in RB0. |
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