Cantafford
Member
Hello,
I'm trying to control a motor via PWM pulses with PIC18f2580.
My input frequency is 8Mhz and I'm trying to implement a 50HZ(20ms time period) pulse with 75% duty cycle.
Preescaler was set to 1:1. I have calculated that for a 75% duty cycle the on time should be 15ms and off time 5ms.
Number of instruction cycles in 15ms is equal to 30.000 according to my calculations.
So I set(or tried to), the CCP1 module to generate an interrupt on match(when TMR1 reaches 30.000 counting from 0) so I have 15ms elapsed by then. When the interrupt is generated, the program is supposed to drive the pin low and keep it there for 5ms.
This is the program that I wrote:
And the header:
As the program starts the motor gets energized just for a short time then it stays off forever.
Basically if there were a led instead of the motor it would flash for a quick period(probably 15ms) then stay off forever. Please help me in correcting this issue.
I'm trying to control a motor via PWM pulses with PIC18f2580.
My input frequency is 8Mhz and I'm trying to implement a 50HZ(20ms time period) pulse with 75% duty cycle.
Preescaler was set to 1:1. I have calculated that for a 75% duty cycle the on time should be 15ms and off time 5ms.
Number of instruction cycles in 15ms is equal to 30.000 according to my calculations.
So I set(or tried to), the CCP1 module to generate an interrupt on match(when TMR1 reaches 30.000 counting from 0) so I have 15ms elapsed by then. When the interrupt is generated, the program is supposed to drive the pin low and keep it there for 5ms.
This is the program that I wrote:
Code:
/*
* File: pwm.c
* Author: Paul
*
* Created on November 19, 2015, 10:30 AM
*/
#include <stdio.h>
#include <stdlib.h>
#include "pwm.h"
void interrupt CCP1int()
{
if(CCP1IF == 1)
{
__delay_ms(5);
CCP1IF = 0;
}
}
void main()
{
OSCCON = 0x76; // frequency is 8Mhz
TRISCbits.RC2 = 0; // motor is here(made output)
CCP1IE = 1;
GIE = 1;
PEIE = 1;
CCP1CON = 0b00001001; // initialize CCP pin high. on compare match, force CCP pin low(CCPIF set)
CCPR1H = 0x75; // 30000 in CCPR1
CCPR1L = 0x30;
T1CON = 0b11000001; // 1:1 prescaler()
while(1)
{
}
}And the header:
Code:
/*
* File: pwm.h
* Author: Paul
*
* Created on November 19, 2015, 10:30 AM
*/
// PIC18F2580 Configuration Bit Settings
// 'C' source line config statements
#include <xc.h>
// #pragma config statements should precede project file includes.
// Use project enums instead of #define for ON and OFF.
// CONFIG1H
#pragma config OSC = IRCIO67 // Oscillator Selection bits (Internal oscillator block, port function on RA6 and RA7)
#pragma config FCMEN = OFF // Fail-Safe Clock Monitor Enable bit (Fail-Safe Clock Monitor disabled)
#pragma config IESO = OFF // Internal/External Oscillator Switchover bit (Oscillator Switchover mode disabled)
// CONFIG2L
#pragma config PWRT = OFF // Power-up Timer Enable bit (PWRT disabled)
#pragma config BOREN = OFF // Brown-out Reset Enable bits (Brown-out Reset disabled in hardware and software)
#pragma config BORV = 3 // Brown-out Reset Voltage bits (VBOR set to 2.1V)
// CONFIG2H
#pragma config WDT = OFF // Watchdog Timer Enable bit (WDT disabled (control is placed on the SWDTEN bit))
#pragma config WDTPS = 32768 // Watchdog Timer Postscale Select bits (1:32768)
// CONFIG3H
#pragma config PBADEN = OFF // PORTB A/D Enable bit (PORTB<4:0> pins are configured as digital I/O on Reset)
#pragma config LPT1OSC = OFF // Low-Power Timer 1 Oscillator Enable bit (Timer1 configured for higher power operation)
#pragma config MCLRE = OFF // MCLR Pin Enable bit (RE3 input pin enabled; MCLR disabled)
// CONFIG4L
#pragma config STVREN = ON // Stack Full/Underflow Reset Enable bit (Stack full/underflow will cause Reset)
#pragma config LVP = ON // Single-Supply ICSP Enable bit (Single-Supply ICSP enabled)
#pragma config BBSIZ = 1024 // Boot Block Size Select bit (1K words (2K bytes) boot block)
#pragma config XINST = OFF // Extended Instruction Set Enable bit (Instruction set extension and Indexed Addressing mode disabled (Legacy mode))
// CONFIG5L
#pragma config CP0 = OFF // Code Protection bit (Block 0 (000800-001FFFh) not code-protected)
#pragma config CP1 = OFF // Code Protection bit (Block 1 (002000-003FFFh) not code-protected)
#pragma config CP2 = OFF // Code Protection bit (Block 2 (004000-005FFFh) not code-protected)
#pragma config CP3 = OFF // Code Protection bit (Block 3 (006000-007FFFh) not code-protected)
// CONFIG5H
#pragma config CPB = OFF // Boot Block Code Protection bit (Boot block (000000-0007FFh) not code-protected)
#pragma config CPD = OFF // Data EEPROM Code Protection bit (Data EEPROM not code-protected)
// CONFIG6L
#pragma config WRT0 = OFF // Write Protection bit (Block 0 (000800-001FFFh) not write-protected)
#pragma config WRT1 = OFF // Write Protection bit (Block 1 (002000-003FFFh) not write-protected)
#pragma config WRT2 = OFF // Write Protection bit (Block 2 (004000-005FFFh) not write-protected)
#pragma config WRT3 = OFF // Write Protection bit (Block 3 (006000-007FFFh) not write-protected)
// CONFIG6H
#pragma config WRTC = OFF // Configuration Register Write Protection bit (Configuration registers (300000-3000FFh) not write-protected)
#pragma config WRTB = OFF // Boot Block Write Protection bit (Boot block (000000-0007FFh) not write-protected)
#pragma config WRTD = OFF // Data EEPROM Write Protection bit (Data EEPROM not write-protected)
// CONFIG7L
#pragma config EBTR0 = OFF // Table Read Protection bit (Block 0 (000800-001FFFh) not protected from table reads executed in other blocks)
#pragma config EBTR1 = OFF // Table Read Protection bit (Block 1 (002000-003FFFh) not protected from table reads executed in other blocks)
#pragma config EBTR2 = OFF // Table Read Protection bit (Block 2 (004000-005FFFh) not protected from table reads executed in other blocks)
#pragma config EBTR3 = OFF // Table Read Protection bit (Block 3 (006000-007FFFh) not protected from table reads executed in other blocks)
// CONFIG7H
#pragma config EBTRB = OFF // Boot Block Table Read Protection bit (Boot block (000000-0007FFh) not protected from table reads executed in other blocks)
#define _XTAL_FREQ 8000000As the program starts the motor gets energized just for a short time then it stays off forever.
Basically if there were a led instead of the motor it would flash for a quick period(probably 15ms) then stay off forever. Please help me in correcting this issue.
