PIC16F877A-HITECHC Part-2 UART & EEPROM

SERIAL COMMUNICATION
UART

Transmission

#include<pic.h>

#define _XTAL_FREQ 16000000 void main() { SPEN=1; //enables serial port SYNC=0; //setting in asynchronous mode BRGH=0; //selects low speed baud rate SPBRG=25; //setting baud rate @ 9600 TXEN=1; //enables transmission TX9=0; //sets transmission in 8-bit mode while(1) { if(TRMT==1) //check status of transmit shift register status for empty { TXREG='A'; // writes ascii value of letter A } } }

Reception

Note-- i have used PORTB to see incoming ascii value

#include<pic.h>
#define _XTAL_FREQ 16000000
void main()
{
SPEN=1; //enables serial port
SYNC=0; //setting in asynchronous mode
BRGH=0; //selects low speed baud rate
SPBRG=25; //setting baud rate @ 9600
CREN=1; //enables reception
RX9=0; //sets reception in 8-bit mode
TRISB=0;
PORTB=0;
while(1)
{
PORTB=(RCREG-0x30); // writes ascii value of letter A
}
}

see software UART at http://jimmyjosep.blogspot.in/2013/11/under-standing-uartsoft.html

EEPROM

Steps to ------Read

1.     Specify the memory location in EEADR (EEADR=4;)

2.     Clear the EEPGD bit (EEPGD=0 ;)

3.     Read the value from EEDATA register (unsigned short int a =EEDATA ;)

Steps to ------Write

1.     Specify the memory location in EEADR (EEADR=4;)

2.     Write the value to EEDATA register (EEDATA=7;)

3.     Set WREN (WREN=1;)

4.     Clear the EEPGD bit (EEPGD=0 ;)

5.      Write 55h to EECON2  (EECON2=0x55;)

6.      Write AAh to EECON2  (EECON2=0xAA;)

7.     Set the WR bit (WR=1;)

#include<pic.h>
#define  _XTAL_FREQ 16000000
__CONFIG(0x3f7a);
unsigned short int eeread();
eewrite(unsigned short int ,unsigned short int );

main()
{
eewrite(4,'1');
unsigned short int a=eeread(); //data from eeprom
TRISB=0;
PORTB=a;
while(1) ;
}  

unsigned short int eeread()
{
EEADR=4;
EEPGD=0;
unsigned short int z =EEDATA;
return z;
}

eewrite(unsigned short int x,unsigned short int y)
{
EEADR=x;
EEDATA=y;
WREN=1;
EEPGD=0 ;
EECON2=0x55;
EECON2=0xAA;
WR=1;
}