UART (Universal Asynchronous Receiver-Transmitter) is a crucial communication protocol widely used in embedded systems for serial communication. In the context of microchip microcontrollers, UART is essential for enabling communication between the microcontroller and other devices such as sensors, computers, and other microcontrollers. This article will guide you through the process of implementing UART_Receive on a microchip microcontroller, highlighting its importance and providing practical examples to help you get started.

Examples:

Example 1: Basic UART_Receive Implementation

Step 1: Configure the UART Module

First, you need to configure the UART module on your microchip microcontroller. This involves setting the baud rate, enabling the UART module, and configuring the RX pin.

#include <xc.h>

#define _XTAL_FREQ 20000000  // Define the system clock frequency

void UART_Init(long baud_rate) {
    unsigned int x;
    x = (_XTAL_FREQ - baud_rate*64)/(baud_rate*64); // Calculate the baud rate generator value
    if(x > 255) {
        x = (_XTAL_FREQ - baud_rate*16)/(baud_rate*16); // Adjust for high-speed mode
        BRGH = 1;  // Set high-speed mode
    }
    if(x < 256) {
        SPBRG = x;  // Set the baud rate generator register
        SYNC = 0;   // Set asynchronous mode
        SPEN = 1;   // Enable the serial port
        TXEN = 1;   // Enable transmission
        CREN = 1;   // Enable continuous reception
        TX9 = 0;    // Set 8-bit transmission
        RX9 = 0;    // Set 8-bit reception
    }
}

void main() {
    UART_Init(9600); // Initialize UART with 9600 baud rate
    while(1) {
        // Main loop
    }
}

Step 2: Implement the UART_Receive Function

Next, implement the function to receive data via UART. This function will wait for data to be received and then return the received byte.

char UART_Receive() {
    while(!RCIF);  // Wait until the reception is complete
    return RCREG;  // Return the received byte from the receive register
}

void main() {
    UART_Init(9600); // Initialize UART with 9600 baud rate
    char received_data;
    while(1) {
        received_data = UART_Receive(); // Receive data
        // Process the received data
    }
}

Example 2: UART_Receive with Interrupts

Step 1: Configure UART with Interrupts

To handle UART reception more efficiently, you can use interrupts. First, configure the UART module to enable receive interrupts.

#include <xc.h>

#define _XTAL_FREQ 20000000  // Define the system clock frequency

void UART_Init(long baud_rate) {
    unsigned int x;
    x = (_XTAL_FREQ - baud_rate*64)/(baud_rate*64); // Calculate the baud rate generator value
    if(x > 255) {
        x = (_XTAL_FREQ - baud_rate*16)/(baud_rate*16); // Adjust for high-speed mode
        BRGH = 1;  // Set high-speed mode
    }
    if(x < 256) {
        SPBRG = x;  // Set the baud rate generator register
        SYNC = 0;   // Set asynchronous mode
        SPEN = 1;   // Enable the serial port
        TXEN = 1;   // Enable transmission
        CREN = 1;   // Enable continuous reception
        TX9 = 0;    // Set 8-bit transmission
        RX9 = 0;    // Set 8-bit reception
        RCIE = 1;   // Enable UART receive interrupt
        PEIE = 1;   // Enable peripheral interrupts
        GIE = 1;    // Enable global interrupts
    }
}

void __interrupt() ISR() {
    if(RCIF) {
        char received_data = RCREG;  // Read the received data
        // Process the received data
        RCIF = 0;  // Clear the receive interrupt flag
    }
}

void main() {
    UART_Init(9600); // Initialize UART with 9600 baud rate
    while(1) {
        // Main loop
    }
}