uart communication with pic16f886

uart communication with pic16f886

Postby ajitnayak87 » Tue Nov 28, 2017 1:46 pm

I am using PIC16F886 with 11.059Mhz crystal. I have tested below code with PIC18F24K40 its working fine with 8Mhz internal oscillator.
When i test below code with 11.059 crystal oscilator i am getting garbage value.
Since both pin configration are equal i dont know why it give garbage value

Code: Select all
#include <htc.h>
#include <stdio.h>
#include<pic.h>
#include<stdint.h>
#include "delay.h"
//#define _XTAL_FREQ 11.059e6
unsigned int i=0;


#define LED_RX RC7 // Pin assigned RX LED
#define LED_TX RC6 // Pin assigned TX LED
#define LED RC2 // Pin assigned for LED
#define DE RC5
#define RECEIVE 0
#define TRANSMIT 1
#define READ_REG 3
#define WRITE_REG 6
#define ILLEGAL_DATAVALUE 0x03
#define FALSE 0
#define TRUE 1
#define METER_ID 1
unsigned int j=0;
unsigned char* str;
unsigned int count = 0;
char data = 0;
unsigned char rxbuf[50];
unsigned char ser_data[95];
unsigned char crc_data[95];
unsigned char Max_scroll = 0;
unsigned char buff[10];
volatile uint8_t index = 0, rec_flag = 0, Delay_count = 0, Id[10], Buffer_count = 0, Cal_count = 0, Disp_count = 0, inc = 0, One_sec_update = 0, Auto_scroll_count = 0;
char data1[10];
unsigned char buf[20];







unsigned short int cnt, num,Dgt=0;

unsigned int j;
#define Notes_Index 25

unsigned int Toff_counter=0;
unsigned int POn_Flag=1;
unsigned int Poff_Flag=0;




void Serial_1_Send_byte(uint8_t trbuf1)
{
TXREG = trbuf1;
while(TRMT==0);

}


void Send_string_uart1(const unsigned char *string)
{
    unsigned char i = 0;

    do {
        TXREG = string[i++];
        while(TRMT==0);
    } while (string[i] != '\0');
}

char Serial_Receive_byte()
{
   
   while(0==PIR1bits.RCIF);
    return RCREG;
   
}

char usart_RxString()
{

   while(*str !='\0')
   { // while not end of string
      while(0==PIR1bits.RCIF);
       RCREG = *str; // read next character
       str++; // increment pointer to next character
   }
       return RCREG; // return the contents of uart
}
void Timer1_Interrupt()
{
               
 INTCON = 0b00000000;
 PIE1=0b00000001;
 PIR1=0x01;
 TMR1H=0x0B;
 TMR1L=0xDC;
T1CON=0x31;
                // T1CON=0x01;
}


void Init_Controller()
 {
  cnt=100;
   TRISC = 0x80; //RX port configured as input
    PORTC = 0x80;
    TRISB=0X00;
    PORTB = 0X00;
   TRISA=0X00;
    PORTA=0X00;
    ADCON0 = 0b00000000;
    ANSEL = 0b00000000;
    Timer1_Interrupt();
    LED=0;

}

//Below code make Ton and Toff time in equal Interval


void interrupt isr(void)
{
  if(TMR1IF==1)
    {
     TMR1H=0xF8;
     TMR1L=0xE8;
    TMR1IF=0;
     Dgt++;
   {
    LED =! LED;
   }
  }
                                     
  }



void Serial_1_Init()
{
                //SPBRG1=103; // Baud Rate 9600
                //SPBRG1=51; // Baud Rate 19200
                SPBRGH= 0x00; // 9600 Baud Rate for 64Mhz
                SPBRG = 0x17;
                TXSTA=0b00100010; // Low Speed mode
                RCSTA=0b10010000;
                BAUDCTL=0b01001000; //16bit baudrate has used
// RCIE=1;
// RCIF=0;
//CCP1IE=1;
}




void UART_Init(int baudRate)
{
    TRISC=0x80; // Configure Rx pin as input and Tx as output
                TXSTA=0b00100010; // Low Speed mode
                RCSTA=0b10010000;
    SPBRG = (11059200UL/(long)(64UL*baudRate))-1;
                RCIE=1;
// RCIF=0;
//CCP1IE=1;
}

void UART_TxChar(char ch)
{
    while(TXIF==0); // Wait till the transmitter register becomes empty
    TXIF=0; // Clear transmitter flag
    TXREG=ch; // load the char to be transmitted into transmit reg
}


char UART_RxChar()
{
    while(RCIF==0); // Wait till the data is received
    RCIF=0; // Clear receiver flag
    return(RCREG); // Return the received data to calling function
}


void main(void)
  {

             Init_Controller();
             Timer1_Interrupt();
            Serial_1_Init();
         // UART_Init(9600);
           GIE=1;
           PEIE=1;
           TMR1IE=1;
  unsigned char c=0;
                while(1)
                {
    Send_string_uart1("Welcome back");
// Serial_1_Send_byte(1);
//UART_TxChar(1);
DelayMs(1000);
                }


}






ajitnayak87
 
Posts: 3
Joined: Tue Aug 01, 2017 1:37 pm

Re: uart communication with pic16f886

Postby ric » Tue Nov 28, 2017 10:17 pm

Code: Select all
void Serial_1_Init()
{
                SPBRGH= 0x00; // 9600 Baud Rate for 64Mhz
                SPBRG = 0x17;
                TXSTA=0b00100010; // Low Speed mode
                RCSTA=0b10010000;
                BAUDCTL=0b01001000; //16bit baudrate has used
}

The datasheet tells you to use decimal 71 in SPBRG to get 9600 at 11.0692MHz with BRGH=0 and BRG16=1,
but you are using 0x17 which is decimal 23. That will give 28800 baud.

You seem to have two versions of each routine.
Your UART_TxChar() is better than your Serial_1_Send_byte() routine, but it is pointlessly trying to clear TXIF.
That is a read-only flag. The only way to clear it is by writing to TXREG, which is the next thing you do anyway.
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