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javi.ar
Joined: 17 Feb 2006
Posts: 59
Location: Argentina
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| Timer miss counting |
 Posted: Mon Aug 29, 2011 11:54 am |
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Hi , I am trying to count cycles with timer0 (8 bits) in 18f4550. CCS Ver 4.108.
It should interrupt every 51.2us and in 1 second I should count someting aroung 20K. But after I delay 1sec I only count 3000. What could be wrong? I was reading about, corrected some lines , but no effect so far. Thanks a lot, here is the code.
| Code: |
#include <18F4550.h>
#device adc=8
#FUSES NOWDT //No Watch Dog Timer
#FUSES WDT128 //Watch Dog Timer uses 1:128 Postscale
#FUSES HSPLL //High Speed Crystal/Resonator with PLL enabled
#FUSES NOPROTECT //Code not protected from reading
#FUSES NOBROWNOUT //No brownout reset
#FUSES BORV20 //Brownout reset at 2.0V
#FUSES PUT //Power Up Timer
#FUSES NOCPD //No EE protection
#FUSES STVREN //Stack full/underflow will cause reset
#FUSES NODEBUG //No Debug mode for ICD
#FUSES NOLVP //No low voltage prgming, B3(PIC16) or B5(PIC18) used for I/O
#FUSES NOWRT //Program memory not write protected
#FUSES NOWRTD //Data EEPROM not write protected
#FUSES IESO //Internal External Switch Over mode enabled
#FUSES FCMEN //Fail-safe clock monitor enabled
#FUSES NOPBADEN //PORTB pins are configured as digital I/O on RESET
#FUSES NOWRTC //configuration not registers write protected
#FUSES NOWRTB //Boot block not write protected
#FUSES NOEBTR //Memory not protected from table reads
#FUSES NOEBTRB //Boot block not protected from table reads
#FUSES NOCPB //No Boot Block code protection
#FUSES NOMCLR //Master Clear pin used for I/O
#FUSES LPT1OSC //Timer1 configured for low-power operation
#FUSES NOXINST //Extended set extension and Indexed Addressing mode disabled (Legacy mode)
#FUSES PLL12 //Divide By 12(48MHz oscillator input)
#FUSES CPUDIV4 //System Clock by 4
#FUSES USBDIV //USB clock source comes from PLL divide by 2
#FUSES VREGEN //USB voltage regulator enabled
#FUSES ICPRT //ICPRT enabled
#use delay(crystal=20000000, clock=5000000)
//////////////////////////////////////////////////////////////////////////////////
#include <velocidad.h>
// Definicion de DEBUG.
#define DEBUG
//#define USB
#ZERO_RAM
#id CHECKSUM
#define MAX_TIMER_COUNT 0xFF // Si el timer es de 16bits 0xFFFF
#define LED PIN_C2
// Definicion de los registros de calculo
unsigned int16 contador_tmr_int =0;
unsigned long time1 =0;
unsigned long time2 =0;
unsigned int velocidad =0;
//
#int_TIMER0
void TIMER0_isr(void)
{
contador_tmr_int++;
}
// Definiciones de Pines del LCD
#define LCD_ENABLE_PIN PIN_D2
#define LCD_RS_PIN PIN_D0
#define LCD_RW_PIN PIN_D1
#include <lcd.c>
//
#include <funciones.h>
void main()
{
lcd_init(); //Inicializo el LCD
setup_adc_ports(NO_ANALOGS|VSS_VDD);
setup_adc(ADC_CLOCK_DIV_2);
//setup_psp(PMP_DISABLED);
setup_spi(SPI_SS_DISABLED);
setup_wdt(WDT_OFF);
//setup_wdt(WDT_ON);
//setup_timer_0(RTCC_INTERNAL); // 16 bits
setup_timer_0(RTCC_INTERNAL|RTCC_8_bit); // RES .2us OVRFLW 51.2us
//setup_timer_1(T1_INTERNAL|T1_DIV_BY_1); // RES .2us OVRFLW 13.1us - 3.6 m/s -> km/h
setup_timer_1(T1_INTERNAL|T1_DIV_BY_1); // RES 1.6us OVRFLW 104ms - 0.28 km/h -> m/s
setup_timer_2(T2_DISABLED,0,1);
setup_timer_3(T3_DISABLED|T3_DIV_BY_1);
setup_ccp1(CCP_OFF);
setup_comparator(NC_NC_NC_NC);
enable_interrupts(INT_TIMER0);
enable_interrupts(GLOBAL);
while (TRUE) {
contador ();
delay_ms (1000);
output_toggle (LED);
}
}
//////////////////////////////////////////////////////////////////////////
long contador (void){
int16 total,loc_copy;
//disable_interrupts(INT_TIMER0);
loc_copy = contador_tmr_int;
#ifdef DEBUG
printf (lcd_putc, "\nO %Lu ",loc_copy);
#endif
// Inicializo el contador de interrupciones.
contador_tmr_int =0;
//enable_interrupts(INT_TIMER0);
return total;
}
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Thanks in advance |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Mon Aug 29, 2011 12:04 pm |
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| Quote: | #FUSES HSPLL //High Speed Crystal/Resonator with PLL enabled
#FUSES PLL12 //Divide By 12(48MHz oscillator input)
#FUSES CPUDIV4
#use delay(crystal=20000000, clock=5000000)
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What is the frequency of the external crystal or oscillator that you have connected to the PIC ?
Is it a crystal, or is it an oscillator ?
What frequency do you want PIC to run at ? |
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asmboy
Joined: 20 Nov 2007
Posts: 2128
Location: albany ny
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| Posted: Mon Aug 29, 2011 12:43 pm |
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my very quick calc says:
for "RES 1.6us OVRFLW 104ms"
on timer one
you would use a 2.5MHZ ext clock or rock
and NO PLL to make that timer math work out
how did you come to expect those params with a 20mhz clock
and a PLL multiplier no less ?????? |
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javi.ar
Joined: 17 Feb 2006
Posts: 59
Location: Argentina
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| Posted: Mon Aug 29, 2011 2:20 pm |
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Well those math came out from the PIC wizard.
I have a 20Mhz crystal attached and I want to use the config for USB output.
So I have no limits for clock speed as long as I know the overflow/interrupt timing and USB working full speed.
Thanks a lot. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Mon Aug 29, 2011 2:30 pm |
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These are the fuse settings for a 20 MHz crystal, with the PLL, to give
a CPU clock of 48 MHz. These fuses will also work with the USB module.
| Code: |
#include <18F4550.h>
#fuses HSPLL,NOWDT,NOPROTECT,NOLVP,USBDIV,PLL5,CPUDIV1,VREGEN
#use delay(clock=48M)
//==========================
void main()
{
while(1)
{
output_high(PIN_B0);
delay_ms(500);
output_low(PIN_B0);
delay_ms(500);
}
}
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javi.ar
Joined: 17 Feb 2006
Posts: 59
Location: Argentina
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| Posted: Mon Aug 29, 2011 2:41 pm |
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| Ok thanks a lot for the reply, I will give a try right now, and let you know. Thanks as usual for the invaluable support. |
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javi.ar
Joined: 17 Feb 2006
Posts: 59
Location: Argentina
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| Posted: Mon Aug 29, 2011 4:43 pm |
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| Yes, now the readings are as predicted. Thanks again. I should keep on reading. |
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