RS232-MUX

/*

 * File:   main.c

 * Author: eniro

 *

 * Created on March 25, 2024, 3:51 PM

 */

#define F_CPU 24000000UL

#include <xc.h>

#include <util/delay.h>

#include <avr/interrupt.h>

//USART setup

#define UART_BAUD_VALUE     10000 // 10000 is equivalent as 9600 bauds according to datasheet

#define USART0_REG          0x3 

//OSC. setup

#define FREQSEL     0x9

#define _FREQSEL_REG_WR     ((FREQSEL) << 2)

#define _USART0_REG_WR      (USART0_REG & 0x7)

//Private vars

uint8_t _rxReicv = 0; // temp byte

uint8_t _rxBuf[256]; //back end serial buffer

uint16_t bytesAvailable = 0; //show if bytes available...

uint8_t rxRead(void); //read 1 byte from buffer

int main(void) {

    uint8_t localBuf[50];

    int k = 0;

    PORTD.DIR = 0x01; // DEBUG LED

    PORTA.DIR = 0x0D; //Set TX/RX IO and RX/TX debug leds for UART0

    PORTB.DIR = 0x0D; //Set TX/RX IO and RX/TX debug leds for UART3

    PORTC.DIR = 0x0D; //Set TX/RX IO and RX/TX debug leds for UART1

    PORTE.DIR = 0x0D; //Set TX/RX IO and RX/TX debug leds for UART2

    PORTF.DIR = 0x0D; //Set TX/RX IO and RX/TX debug leds for UART4

    //PORTMUX.USARTROUTEA = _USART0_REG_WR; //set TX and RX on PD4 and PD5 pins

    _PROTECTED_WRITE(CLKCTRL.OSCHFCTRLA, _FREQSEL_REG_WR); //switch to 24 MHz

    USART0.BAUD = UART_BAUD_VALUE; 

    USART0.CTRLA = 0x80; //enable RX complete interrupt

    USART0.CTRLB = 0xD0; //Enable TX and RX sending

    sei(); //never forget to enable global interrupt mask !

    //bad guy

    PORTA.OUT = 0x04;

    _delay_ms(250);

    PORTA.OUT = 0x0C;

    _delay_ms(250);

    PORTA.OUT = 0x00;

    PORTB.OUT = 0x04;

    _delay_ms(250);

    PORTB.OUT = 0x0C;

    _delay_ms(250);

    PORTB.OUT = 0x00;

    PORTC.OUT = 0x04;

    _delay_ms(250);

    PORTC.OUT = 0x0C;

    _delay_ms(250);

    PORTC.OUT = 0x00;

    PORTE.OUT = 0x04;

    _delay_ms(250);

    PORTE.OUT = 0x0C;

    _delay_ms(250);

    PORTE.OUT = 0x00;

    PORTF.OUT = 0x04;

    _delay_ms(250);

    PORTF.OUT = 0x0C;

    _delay_ms(250);

    PORTF.OUT = 0x00;

    while(1)

    {

        USART0.TXDATAL = 0x45;

        PORTD.OUT ^= 0x01;

        PORTB.OUT ^= 0x01;

        PORTC.OUT ^= 0x01;

        PORTE.OUT ^= 0x01;

        PORTF.OUT ^= 0x01;

        _delay_ms(10);

        if(bytesAvailable > 0) //check if we have bytes to read

        {

            localBuf[k] = rxRead(); //store byte into buffer

            k++; //increment to next byte

        }

        //check if the 2 first bytes match with theses values

        if(localBuf[0] == 0x42 && localBuf[1] == 0x64) 

        {

            //Clear buffer

            localBuf[0] = 0x00;

            localBuf[1] = 0x00;

            k = 0;

            PORTA.OUT ^= 0x1; //Set flag on led

        }

        //Just in case if bytes does not match, clear counter

        if(k >= 2)

            k = 0;

        //_delay_ms(200);

    }

    return 0;

}

///////////////////////////////////////////////////////////

//Functions / macros

uint8_t rxRead(void) //Read one byte from buffer

{

    uint8_t result = _rxBuf[0]; //get byte in order (FIFO)

    for(uint8_t j = 0; j < 255; j++) //shift bytes

    {

        _rxBuf[j] = _rxBuf[j+1];

    }

    if(bytesAvailable > 0)

        bytesAvailable--; //remove 1 byte

    return result;

}

ISR(USART0_RXC_vect)

{

    //while((USART0.RXDATAH & 0x80) == 0x80);

    _rxReicv = USART0.RXDATAL; //read buffer

    _rxBuf[bytesAvailable] = _rxReicv; //Add one byte to the buffer

    _rxReicv = 0x00; //clear value

    if(bytesAvailable < 255) //ensure not to overflow buffer size...

        bytesAvailable++; //a new byte is available into the buffer

        //PORTA.OUT ^= 0x3; //debug led

}