I have doubt in PIC16f1527 baud rate formula

[ragav4456]

Hi friends

I have doubt in UART baudrate formula

SYNC=BRGH=BRG16=0, formula FOSC/[64(n+1)]
SYNC=BRG16=0,BRGH=1, formula FOSC/[16(n+1)]

in my program SYNC=0;BRG16=1;BRGH=1;

can i use this formula
SYNC=0;BRGH=BRG16=1, formula FOSC/[4(n+1)]

 

[Tahmid]

Yes, in fact that is the formula you have to use. Just refer to the table in the datasheet:

Hope this helps.
Tahmid.

 

[ragav4456]

kindly check the program


How to change the formula?

#include <htc.h>
#include "sci.h"

unsigned int uiRS232Error = 0;

unsigned char sci_Init(unsigned long int baud, unsigned char ninebits)
{
	int X;
	unsigned long tmp;
	uiRS232Error = 0;

	tmp = 16UL * baud;
	X = (int)(FOSC/tmp) - 1;
	if((X>255) || (X<0))
	{
		tmp = 64UL * baud;
		X = (int)(FOSC/tmp) - 1;
		if((X>255) || (X<0))
		{
			return 1;	
		}
		else

			TX1STAbits.BRGH = 0;	/* low baud rate */
	}
	else
	TX1STAbits.BRGH = 1;	/* high baud rate */
	SPBRG = X;	/* set the baud rate */
        BAUD1CONbits.BRG16=1;
	BAUD1CONbits.ABDOVF=0;
	BAUD1CONbits.RCIDL=0;
	BAUD1CONbits.SCKP=0;
	BAUD1CONbits.WUE=0;
	BAUD1CONbits.ABDEN=1;
	TX1STAbits.SYNC = 0;           /* asynchronous */
	TX1STAbits.SENDB = 0;

	RC1STAbits.SPEN = 1;	/* enable serial port pins */
	RC1STAbits.CREN = 1;	/* enable reception */
	RC1STAbits.SREN = 0;	/* no effect */
	PIE1bits.TX1IE = 1;	/* disable tx interrupts */
	PIE1bits.RC1IE = 1;	/* disable rx interrupts */
	TX1STAbits.TX9  = ninebits?1:0;	/* 8- or 9-bit transmission */
	RC1STAbits.RX9  = ninebits?1:0;	/* 8- or 9-bit reception */
	RC2STAbits.ADDEN=0;
	TX1STAbits.TXEN = 1;	/* enable the transmitter */
	PIR1bits.TX1IF = 0;	/* enable tx interrupts */
	PIR1bits.RC1IF = 0; /* enable rx flag */

	return 0;
}

void sci_PutByte(unsigned char byte)
{	unsigned long ulICnt=0;
	
	uiRS232Error = 0;

	while(!PIR1bits.TX1IF && ulICnt < WAIT_TICK_MAX)	
	{	ulICnt++;
	}
	TX1REG = byte;

	if(ulICnt >= WAIT_TICK_MAX)
	{	uiRS232Error = 1;
	}
	return;
}

unsigned char sci_GetByte(void)
{	unsigned long ulICnt=0;

	uiRS232Error = 0;

	while(!PIR1bits.RC1IF && ulICnt < WAIT_TICK_MAX)	
	{	ulICnt++;
	}

	sci_CheckOERR();

	if(ulICnt >= WAIT_TICK_MAX)
	{	uiRS232Error = 1;
	}

	return RC1REG;	/* RXD9 and FERR are gone now */
}

unsigned char sci_CheckOERR(void)
{
	if(RC1STAbits.OERR)	
	{
		RC1STAbits.CREN = 0;
		RC1STAbits.CREN = 1;
		return 1;
	}
	
	return 0;
 }

#define sci_PutNinth(bitnine)	(TX9D = bitnine?1:0;)

unsigned char sci_GetNinth(void)
{
	while(!PIR1bits.RC1IF)
		continue;
	
	return RC1STAbits.RX9D;	
}

unsigned char sci_GetFERR(void)
{
	while(!PIR1bits.RC1IF)
		continue;
	
	return RC1STAbits.FERR;
}