PIC16F884 PIC microcontroller

Buck Circuit

This is a step-down circuit. SW is connected to PWM here to perform the main work of stepping down. After Vout is divided, the maximum value not exceeding the chip working voltage (5V is also OK) is input to the PIC AN1 port for AD conversion.

The conversion result is displayed on 1602. If the voltage is not the desired voltage, the program changes the PWM duty cycle to achieve the required value.

The main steps are to initialize the 1602 to write data and write instructions and the PIC AD to start the working module. The program is as follows

#include

__CONFIG(0x201A);

#define uint unsigned int

#define uchar unsigned char

#define rs RC4 //Data command

#define en RC5 // Enable terminal

#define DATA PORTD //Data port

//RC1 as PWM output port

const uchar dis1[]="The voltage is:"; //asm("nop");

const uchar dis2[]=" . V";

void delay(uchar time) //1ms

{

uint j;

for(time;time>0;time--)

for(j=160;j>0;j--);

}

void lcd_wcmd(uchar cmd)

{

rs = 0;

en = 0;

DATA = cmd; // pass 8-bit data to 1602 through P0 port

delay(2);

en = 1;

delay(2);

en = 0;

}

void lcd_wdat(uchar dat)

{

rs = 1;

en = 0;

DATA= dat; //Transmit 8-bit data to 1602 through P0 port

delay(2);

en = 1;

delay(2);

en = 0;

}

void lcd_init()

{

TRISC=0Xcf; //1100 1111

TRISD=0X00;

lcd_wcmd(0x38); ////16*2 display, 5*7 dot matrix, 8-bit data

lcd_wcmd(0x0c); //Display on and off cursor

lcd_wcmd(0x06); //Move cursor

lcd_wcmd(0x01); //Clear the LCD display content

}

void pwm_init()

{

TRISC1=1; //CCP2 OUTPUT DISABLE

PR2=0XFF;

CCP2CON=0X3C; //0011(last two digits of CCPR1L))1100 11XX PWM MODE

CCPR2L=0X3F; //CCPR2L:CCP2CON

//0X3F 25%

TMR2IF=0;

T2CON=0X05; //Start timer 2 prescale ratio is 1:4

while(TMR2IF)

{

TMR2IF=0;

TRISC1=0;

}

}

void adc_init()

{

ADCON0=0X45; // f/2 frequency AN1 channel AD conversion completed. Disable ADC

ADCON1=0X80; //Right-aligned reference voltage VSS VDD

TRISA=0X01; //Input

delay(5);

}

void deal_ad()

{

uint temp;

uint ad_sample;

uint result;

uchar a1,a2,a3;

GO_DONE=1;

while(GO_DONE);

ad_sample=ADRESL (ADRESH<<8);

result=(ad_sample*500)>>10; //reference voltage 5V is enlarged 100 times

temp=result;

a1=temp/100;

a2=temp0/10;

a3=temp0;

if(a1!=0)

{

lcd_wcmd(0x80 0x44);

lcd_wdat(a1 0x30);

}

lcd_wcmd(0x80 0x45);

lcd_wdat(a2 0x30);

lcd_wcmd(0x80 0x47);

lcd_wdat(a3 0x30);

}

void lcd_dis()

{

uchar i;

lcd_wcmd(0x80);

i=0; //Set the display position to the 5th character in the first line

while(dis1[i]!='\0')

{ //Display the characters "welcome!"

lcd_wdat(dis1[i]);

i ;

}

lcd_wcmd(0x80 0X40);

i=0; //Set the display position to the 5th character in the first line

while(dis2[i]!='\0')

{ //Display the characters "welcome!"

lcd_wdat(dis2[i]);

i ;

}

}

void main()

{

delay(10);

lcd_init(); //Initialize LCD Just write the starting address

adc_init();

while(1)

{

lcd_dis();

deal_ad();

}

// pwm_init();

while(1);

}

It's not perfect, just for reference. The PWM adjustment is not perfect, but it's not very difficult.