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16F877 timer2 (thanks Tomy for I2C)

 
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Renato and Davide
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16F877 timer2 (thanks Tomy for I2C)
PostPosted: Thu Nov 15, 2001 4:24 am     Reply with quote

---------------------------------------------------------------
For Tomy: a lot of thanks for I2C help. The mistake was the PIC wizard instraction: setup_spi (FALSE); ours code is correct without setup_spi (FALSE).
---------------------------------------------------------------

* We have now a problem with timer2. We have set timer2 in this way:

setup_timer_2(T2_DIV_BY_16,125,1);

We need an interrupt timer every 1 ms but we have seen thet if we write:

setup_adc_ports(RA0_RA1_RA3_ANALOG);
setup_adc(ADC_CLOCK_INTERNAL);
setup_psp(PSP_DISABLED);
setup_wdt(WDT_2304MS);
setup_timer_1(T1_DISABLED);
setup_timer_2(T2_DIV_BY_16,125,1);
setup_ccp1(CCP_OFF);
setup_ccp2(CCP_OFF);
enable_interrupts(INT_EEPROM);
enable_interrupts(INT_TIMER2);
enable_interrupts(INT_RDA);
enable_interrupts(INT_ADC);
enable_interrupts(INT_SSP);
enable_interrupts(global);

we have an interrupt every 13 ms.

The ASM code for setup_wdt(WDT_2304MS) and setup_timer_2(T2_DIV_BY_16,125,1) is:
.................... setup_wdt(WDT_2304MS);
0D43: MOVLW 0F
0D44: MOVWF 77
0D45: MOVLW 07
0D46: BCF 03.5
0D47: CLRF 01
0D48: MOVLW 81
0D49: MOVWF 04
0D4A: BCF 03.7
0D4B: MOVF 00,W
0D4C: ANDLW C0
0D4D: IORLW 0F
0D4E: MOVWF 00
0D4F: CLRWDT
0D50: MOVLW 81
0D51: MOVWF 04
0D52: MOVF 00,W
0D53: ANDLW C0
0D54: IORWF 77,W
0D55: MOVWF 00
.................... setup_timer_1(T1_DISABLED);
0D56: CLRF 10
.................... setup_timer_2(T2_DIV_BY_16,125,1);
0D57: MOVLW 00
0D58: BCF 03.0
0D59: RLF 00,W
0D5A: MOVWF 77
0D5B: RLF 77,F
0D5C: RLF 77,F
0D5D: MOVLW F8
0D5E: ANDWF 77,F
0D5F: MOVF 77,W
0D60: MOVWF 78
0D61: IORLW 06
0D62: MOVWF 12
0D63: MOVLW 7D //The mistake seems to be here
0D64: BSF 03.5
0D65: MOVWF 12


*********************************************

If we traslate setup_timer_2 instraction in first position:

setup_timer_2(T2_DIV_BY_16,125,1);
setup_adc_ports(RA0_RA1_RA3_ANALOG);
setup_adc(ADC_CLOCK_INTERNAL);
setup_psp(PSP_DISABLED);
setup_counters(RTCC_INTERNAL,WDT_2304MS);
setup_wdt(WDT_2304MS);
setup_timer_1(T1_DISABLED);
setup_ccp1(CCP_OFF);
setup_ccp2(CCP_OFF);
enable_interrupts(INT_EEPROM);
enable_interrupts(INT_TIMER2);
enable_interrupts(INT_RDA);
enable_interrupts(INT_ADC);
enable_interrupts(INT_SSP);
enable_interrupts(global);

we have an interrupt every 8 ms.

******************************************

if we comment setup_wdt(WDT_2304MS);

we have an interrupt every 5 ms.

********************************************

- WHAT WE HAVE TO DO TO HAVE ONE INTERRUPT EVERY 1 ms WITH
TIMER2 ?

IDE Version = 2.32
PCB Version = 3.043
PCM Version = 3.043
Thank you for the support. Best regards
___________________________
This message was ported from CCS's old forum
Original Post ID: 1118
Tomi
Guest







Re: 16F877 timer2 (thanks Tomy for I2C)
PostPosted: Thu Nov 15, 2001 11:41 am     Reply with quote

I think you have found a compiler error. To manually override the problem, try this instead of the "setup_timer_2(T2_DIV_BY_16,125,1);" line:
*0x12 = 6; // post-scaler 1:1, timer2 enabled, prescaler=16
*0x92 = 0x7D; // load 125 to PR2


:=--------------------------------------------------------------The mistake was the PIC wizard instraction

I never use wizards: I like to keep the control in my hand.

Brg,
Tomi
___________________________
This message was ported from CCS's old forum
Original Post ID: 1129
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