USART for PIC Microcontrollers

				
					#include <pic16f877a.h>
#include <xc.h>

// Define the frequency of the external crystal oscillator
#define _XTAL_FREQ 20000000  // 20MHz external crystal oscillator frequency
#define BUFFER_SIZE 2 // Adjust the buffer size as needed

volatile char receiveBuffer[BUFFER_SIZE];
volatile unsigned char bufferIndex = 0;

// Function to initialize UART
void UART_Initialize()
{
    //Initialization as shown in section 2.
}

// Function to transmit a character via UART
void UART_Write(char data)
{
    // As shown in section 3.1; you can choose between code 1 or 2.
    // In this example, this function can be removed.
}

void interrupt ISR() {
    if (RCIF) {
        receiveBuffer[bufferIndex] = RCREG; // Read received data and store it in the buffer.
        bufferIndex++; //bufferIndex is reset to 0 in the main loop, after setting the LEDs.
    }
}

// Main function
void main()
{
    UART_Initialize(); // Initialize UART
    
    // Enable global and peripheral interrupts=
    INTCONbits.PEIE = 1; // Enable peripheral interrupts
    PIE1bits.RCIE = 1;   // Enable UART receive interrupt
    INTCONbits.GIE = 1;  // Enable global interrupts
    
    TRISA1 = 0; // Clear the TRISA1 bit to configure it as an output
    TRISB3 = 0; // Clear the TRISB3 bit to configure it as an output

    while(1)
    {
        if (bufferIndex >= 2)
        {
            // At least 2 bytes have been received and stored in the buffer
            char pin = receiveBuffer[0]; // Get the pin information (RA1 or RB3)
            char state = receiveBuffer[1]; // Get the state (High or Low)

            // Process the received data based on pin and state
            if (pin == 'A' && state == 'H')
            {
                // Activate RA1 and set it to High
                RA1 = 1;
                RB3 = 0;
            }
            else if (pin == 'B' && state == 'H')
            {
                // Activate RB3 and set it to High
                RB3 = 1;
                RA1 = 0;
            }
            // Clear the buffer and reset the index for new data
            bufferIndex = 0;
        }

        // Other tasks can be performed here
    }
}