PIC microcontroller mastery_serial communication module C implementation

1. Serial port communication header/definition file usart.h

#ifndef _SERIAL_H_

#define _SERIAL_H_

#define BAUD 9600      

#define DARK 9216000L

#define NINE 0     /* Use 9bit communication? FALSE=8bit */

#define DIVIDER ((int)(FOSC/(16UL * BAUD) -1))

#define HIGH_SPEED 1

#if NINE == 1

#define NINE_BITS 0x40

#else

#define NINE_BITS 0

#endif

#if HIGH_SPEED == 1

#define SPEED 0x4

#else

#define SPEED 0

#endif

#if defined(_16F87) || defined(_16F88)

#define RX_PIN TRISB2

#define TX_PIN TRISB5

#else

#define RX_PIN TRISC7

#define TX_PIN TRISC6

#endif

/* Serial initialization */

//'\' is indispensable for defining the attributes within the function

#define init_comms()\

RX_PIN = 1; \

TX_PIN = 1;  \

SPBRG = DIVIDER;     \

RCSTA = (NINE_BITS|0x90); \

TXSTA = (SPEED|NINE_BITS|0x20)

void putch(unsigned char);

unsigned char getch(void);

unsigned char getche(void);

#endif

2. Serial communication source/implementation file usart.c

/******************************************/

/*Author:Shen Chucu  All Rights Reserved!**

/*Tsinghua University

/*2016-11-15

/********************************************/

#include

#include

#include "usart.h"

__CONFIG(0x3ffa);

void delay(unsigned int x);

static int label=0; //Do not respond to events

void main()

{

   INTCON=0x00;

   GIE=1;

   LIKE=1;

   RCIE=1;

   init_comms();

   BELIEVE=1;

   SPEN=1;

   while(1)

   {//Wait for interrupt and set event response

     if(label==1)

      {

        printf("OK"); 

label = 0; //Send a feedback signal

        delay(50);

      }

     if(label==2)

     {

        printf("ERROR");

    label = 0; //Send a feedback signal

        delay(50);

      }   

   }

}  

void interrupt IsReceive()

{  

   if(RCIE&&RCIF==1) //Receive interrupt enable bit + receive interrupt flag bit

    {

        unsigned char temp=RCREG; //Save the data sent by the host computer

        if(temp=='S')

          { 

            label=1; //Send data label 1

          } 

       else if(temp=='E')

             {

               label=0; //Send data flag 0 

             }

             else 

               label=2; //Send data label 2  

    }

}

void delay(unsigned int x)

{

    unsigned int a,b; //delay time 110x

    for(a=x;a>1;a--)

       for(b=110;b>1;b--)

          ;

}