Using a Microchip PIC16F1788 microcontroller MPLabs IDE X an

Using a Microchip PIC16F1788 microcontroller, MPLabs IDE X, and XC8 C Compiler, write a C program that outputs a PWM signal with 25% duty cycle.

Solution

#define _XTAL_FREQ 20000000 #define TMR2PRESCALE 4 #include // BEGIN CONFIG #pragma config FOSC = HS // Oscillator Selection bits (HS oscillator) #pragma config WDTE = OFF // Watchdog Timer Enable bit (WDT enabled) #pragma config PWRTE = OFF // Power-up Timer Enable bit (PWRT disabled) #pragma config BOREN = ON // Brown-out Reset Enable bit (BOR enabled) #pragma config LVP = OFF // Low-Voltage (Single-Supply) In-Circuit Serial Programming Enable bit (RB3 is digital I/O, HV on MCLR must be used for programming) #pragma config CPD = OFF // Data EEPROM Memory Code Protection bit (Data EEPROM code protection off) #pragma config WRT = OFF // Flash Program Memory Write Enable bits (Write protection off; all program memory may be written to by EECON control) #pragma config CP = OFF // Flash Program Memory Code Protection bit (Code protection off) //END CONFIG long freq; int PWM_Max_Duty() { return(_XTAL_FREQ/(freq*TMR2PRESCALE); } PWM1_Init(long fre) { PR2 = (_XTAL_FREQ/(fre*4*TMR2PRESCALE)) - 1; freq = fre; } PWM2_Init(long fre) { PR2 = (_XTAL_FREQ/(fre*4*TMR2PRESCALE)) - 1; freq = fre; } PWM1_Duty(unsigned int duty) { if(duty<1024) { duty = ((float)duty/1023)*PWM_Max_Duty(); CCP1X = duty & 2; CCP1Y = duty & 1; CCPR1L = duty>>2; } } PWM2_Duty(unsigned int duty) { if(duty<1024) { duty = ((float)duty/1023)*PWM_Max_Duty(); CCP2X = duty & 2; CCP2Y = duty & 1; CCPR2L = duty>>2; } } PWM1_Start() { CCP1M3 = 1; CCP1M2 = 1; #if TMR2PRESCALAR == 1 T2CKPS0 = 0; T2CKPS1 = 0; #elif TMR2PRESCALAR == 4 T2CKPS0 = 1; T2CKPS1 = 0; #elif TMR2PRESCALAR == 16 T2CKPS0 = 1; T2CKPS1 = 1; #endif TMR2ON = 1; TRISC2 = 0; } PWM1_Stop() { CCP1M3 = 0; CCP1M2 = 0; } PWM2_Start() { CCP2M3 = 1; CCP2M2 = 1; #if TMR2PRESCALE == 1 T2CKPS0 = 0; T2CKPS1 = 0; #elif TMR2PRESCALE == 4 T2CKPS0 = 1; T2CKPS1 = 0; #elif TMR2PRESCALE == 16 T2CKPS0 = 1; T2CKPS1 = 1; #endif TMR2ON = 1; TRISC1 = 0; } PWM2_Stop() { CCP2M3 = 0; CCP2M2 = 0; } void main() { unsigned int i=0,j=0; PWM1_Init(5000); PWM2_Init(5000); TRISD = 0xFF; TRISB = 0; PWM1_Duty(0); PWM2_Duty(0); PWM1_Start(); PWM2_Start(); do { if(RD0 == 0 && i<1000) i=i+10; if(RD1 == 0 && i>0) i=i-10; if(RD2 == 0 && j<1000) j=j+10; if(RD3 == 0 && j>0) j=j-10; PWM1_Duty(i); PWM2_Duty(j); __delay_ms(50); }while(1); }