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gpacer68
Joined: 18 Jun 2009
Posts: 4
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| PIC16F1936 timer enable problem |
 Posted: Fri Aug 28, 2009 7:41 am |
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Hello,
I have changed from the PIC 16f886 to the new micro watt 16F1936. The parts are pin compatible. The code ported over very easily thanks to CCS abstractions. :-) I am currently having a problem making the timers work. I have tried timer0, timer2 and timer4 and none of them will actually tic or start resulting in the interrupt not firing either.
any help would be great.
I am running v4.093 of PCW IDE
| Code: | #include <16F1936.h>
#include <stdio.h>
#include <stdlib.h>
#fuses noDEBUG // debug - in circuit debugger enabled on RB6 and RB7 - DISABLED
#fuses noLVP // LVP - low voltage enable - DISABLED
#fuses noFCMEN // Fail safe clock monitor - DISABLED
#fuses noIESO // IESO - internal / external switch over DISABLED
#fuses BROWNOUT // Brown out reset selection bits - 11 BOR ENABLED
#fuses noCPD // CPD - date code protect DISABLED
#fuses noPROTECT // CP - code protect DISABLED
#fuses MCLR // MCLRE - RE3 is MCLR
#fuses noSTVREN
#fuses noPUT // PWRTE - power up timer enable bit DISABLED
#fuses INTRC_IO, noWDT
// preprocessor directive that defines fuses for the chip
//application will use the internal oscillator at 8MHz.
//compiler will set INTOSC_IO config bit, and set the internal
//oscillator to 8MHz.
#use delay(internal=4M)
#use rs232(baud=19200, xmit=PIN_C6, rcv=PIN_C7)
unsigned int16 _restart_reason;
#define INTS_PER_SECOND 122
int _new_sec; // A running seconds counter
int secs; // A running seconds counter
int int_count; // Number of interrupts before a second has elapsed
//****************
#INT_TIMER0
void timer0_isr(void)
{
putc('+');
if ( --int_count == 0 )
{
secs++;
_new_sec++;
int_count = INTS_PER_SECOND;
if ( secs >= 60 ) {
secs=0;
}
}
}
//*******************
//*******************
//**
//**
void timer_init()
{
_new_sec = 0;
secs = 0;
int_count = INTS_PER_SECOND;
set_timer0(5);
setup_timer_0(RTCC_INTERNAL|RTCC_DIV_64);
enable_interrupts(INT_TIMER0);
enable_interrupts(GLOBAL);
/*
You see the 'Timer 0 (AKA RTCC)" in the first comments line? Looking at your program you
should get a toggle on the test pin every 1.6 seconds right? You are using a 4Mhz crystal
so your basic timer0 tick (the time it takes the timer to go up one count) is 1us. You are
using it in 8 bit mode and a prescaler of 64. So timer0 overflows in 1us*2^8*64 = 0.0164 seconds.
Everytime it overflows you enter the ISR and increase the overflow count by one.
Once counts hits 100 the pin is toggled. So 0.0164*100 = 1.64 seconds.
8Mhz so timer tick is 0.5us
8 bit mode and a prescaler of 64
each overflow happens at :
0.5us*2^8*64 = 0.008192 secs
1/0.008192 = 122 overflows/INTS per second
*/
}
//*******************
//*******************
//**
//**
//#separate
#zero_ram
void main()
{
int b;
int16 x;
setup_oscillator( OSC_4MHZ | OSC_PLL_OFF );
//** get the reason for last reboot for later saving to EEPROM
_restart_reason = restart_cause();
switch(_restart_reason)
{
case MCLR_FROM_RUN: //** on reset or WD time out this reason gets set
printf("mclr\n\r");
break;
case WDT_TIMEOUT:
printf("wdt\n\r");
break;
case NORMAL_POWER_UP:
printf("norm\n\r");
break;
case BROWNOUT_RESTART:
printf("brown\n\r");
break;
default:
printf("other\n\r");
};
// Set PORT to all output
set_tris_a(0);
output_a(0); //all port A off
//** all PORTB leds OFF
set_tris_b(0);
output_b(0);
printf("hello !!\n\r");
delay_ms(2000);
timer_init();
output_b(1);
b=0;
while(1)
{
delay_ms(1000);
//** flash status led every second
#if 1
if ( b == 0 ) {
output_high(PIN_B0);
b = 1;
}
else {
output_low(PIN_B0);
b = 0;
}
#endif
printf("+ %d", get_timer0());
if ( _new_sec == 0 )
continue;
_new_sec = 0;
printf(".");
}
}
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_________________
gpacer68 |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Fri Aug 28, 2009 11:40 am |
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Try a simple program which toggles an LED that is connected to pin C0.
Connect a 470 ohm resistor between pin C0 and the anode of the LED.
The connect the cathode of the LED to ground. This assumes the PIC
is running at +5v. This program should toggle the LED on/off at about
a 1 Hz rate. I don't have this PIC to test in hardware, so I don't
guarantee that this will work.
| Code: |
#include <16F1936.h>
#fuses INTRC_IO,NOWDT,NOPROTECT,BROWNOUT,PUT,NOLVP
#use delay(clock=4000000)
#define LED_PIN PIN_C0
#int_timer1
void timer1_isr(void)
{
output_toggle(LED_PIN);
}
//======================================
void main()
{
output_low(LED_PIN);
setup_timer_1(T1_INTERNAL | T1_DIV_BY_8);
set_timer1(0);
clear_interrupt(INT_TIMER1);
enable_interrupts(INT_TIMER1);
enable_interrupts(GLOBAL);
while(1);
} |
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gpacer68
Joined: 18 Jun 2009
Posts: 4
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| Posted: Sat Aug 29, 2009 3:04 pm |
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I tried your program and it worked, however when I changed it to use timer0 and I could not get that timer to work. I obviously changed the interrupt handler to account for the new frequency of interrupts with timer0.
In reading the list of changes to the compiler (recall I was at 4.093) it appears that more support for the new midrange PICs were added in newer versions. So I upgraded to 4.098 and the timer0 code worked as is.
So, the summary is, it appears the 4.093 did not fully support the PIC16F1936 timer0 and timer 2/4/6 features of this chip. When I upgraded to 4.098 these timers worked.
Thanks for the help.
_________________
gpacer68 |
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