UART Communication in PIC16F877A
Posted: Sun Sep 27, 2015 12:36 pm
Hi everyone.. i have written UART code in MPLAB using "xc8" compiler for PIC16F877A Microcontroller..code build was successful but while i am simulation code using proteus i am not getting the output in virtual terminal as expected.i am getting some charater like
C0 00 C0 C0 C0 00 C0 00 00 C0 00 C0 C0 C0 C0 C0
00 C0 00 00 C0 C0 00 00 C0 00 C0 00 00 C0 C0 00
C0 C0 00 00 00 C0 C0 C0 C0 00 C0 00 00 C0 C0 C0
C0 C0 C0 C0 C0 00 C0
Frequency used for 9600 baud rate is 4.9152 MHZ so that baud rate error is ZERO. i have set frequency in proteus as same 4.9152 MHZ and baud rate as 9600 in virtual terminal. can anyone suggest weather i am missing something in the code or code is correct .
NOTE: PIC16F877A DOES NOT HAVE ANY INTERNAL OSCILLATOR AS VERIFIED FROM DATASHEET
C0 00 C0 C0 C0 00 C0 00 00 C0 00 C0 C0 C0 C0 C0
00 C0 00 00 C0 C0 00 00 C0 00 C0 00 00 C0 C0 00
C0 C0 00 00 00 C0 C0 C0 C0 00 C0 00 00 C0 C0 C0
C0 C0 C0 C0 C0 00 C0
Frequency used for 9600 baud rate is 4.9152 MHZ so that baud rate error is ZERO. i have set frequency in proteus as same 4.9152 MHZ and baud rate as 9600 in virtual terminal. can anyone suggest weather i am missing something in the code or code is correct .
NOTE: PIC16F877A DOES NOT HAVE ANY INTERNAL OSCILLATOR AS VERIFIED FROM DATASHEET
- Code: Select all
#include<xc.h>
#include<stdio.h>
#include<stdlib.h>
// CONFIG
#pragma config FOSC = HS // Oscillator Selection bits (HS oscillator)
#pragma config WDTE = OFF // Watchdog Timer Enable bit (WDT disabled)
#pragma config PWRTE = ON // Power-up Timer Enable bit (PWRT enabled)
#pragma config BOREN = ON // Brown-out Reset Enable bit (BOR enabled)
#pragma config LVP = OFF // Low-Voltage (Single-Supply)
#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)
#define _XTAL_FREQ 4915200
#define baud_rate 9600
void serial_init(void);
void serial_char(unsigned char);
void serial_string(unsigned char *);
char serial_read(void);
char data_string[16] ="ENTER ANY VALUE";
unsigned char data_buff = 0,data_read =0;
void main()
{
unsigned int i=0;
serial_init();
serial_char('A');
serial_string(data_string);
TRISB =0X00;
PORTB = 0X00;
while(1)
{
if(PIR1bits.RCIF)
{
data_buff = serial_read();
switch(data_buff)
{
case 0x31:
{
PORTB = 0X01;
break;
}
case 0x32:
{
PORTB = 0X02;
break;
}
case ' ':
{
PORTB = 0X03;
break;
}
default:
PORTB = 0XAA;
}
}
}
}
void serial_init()
{
char speed = (_XTAL_FREQ - (baud_rate*16))/(baud_rate*16);
TRISCbits.TRISC6 = 0;
TRISCbits.TRISC7 = 1;
SPBRG = speed;
TXSTAbits.BRGH = 1; //REQUIRED FOR HIGH BAUD RATE
TXSTAbits.SYNC = 0; //for Asynchronous communication
RCSTAbits.SPEN = 1; // enable UART
RCSTAbits.CREN = 1; // enable continuous receive enable
TXSTAbits.TXEN = 1; // enable transmission
}
void serial_char(unsigned char data)
{
while(!TXSTAbits.TRMT); //wait for previous transmission to over
TXREG = data;
}
void serial_string(unsigned char *str)
{
while(*str != 0)
{
serial_char(*str++);
}
}
char serial_read()
{
while(!PIR1bits.RCIF); //check weather reception is complete
data_read = RCREG; //read the RCREG register
if(RCSTAbits.OERR == 1) // check for any over run error
{
RCSTAbits.CREN = 0;
RCSTAbits.CREN = 1;
}
return data_read;
}