uart.c

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#include <avr/interrupt.h>
#include <avr/io.h>
#include <stdint.h>
// #include <stdio.h>
#include <util/delay.h>
 
#include "uart.h"
 
char receive_buf = 0;
// ISR(USART0_RXC_vect) { USART_Receive(); }
 
// static FILE stdout_uart =
//     FDEV_SETUP_STREAM(USART_Transmit, USART_Receive, _FDEV_SETUP_RW);
 
int USART_init(struct USART_config *config) {
  uint16_t ubrr = (config->fosc / 16 / config->baud) - 1;
  UBRR0H = (unsigned char)(ubrr >> 8);
  UBRR0L = (unsigned char)ubrr;
 
  // Enable RX & TX & RXC interrupt
  UCSR0B = (1 << RXEN0) | (1 << TXEN0) /*| (1 << RXCIE0)*/;
 
  // Format 9600 8N1
  UCSR0C = (1 << URSEL0) | (0 << USBS0) | (3 << UCSZ00);
 
  // sei();
  // fdevopen(USART_Transmit, USART_Receive);
 
  return 0;
}
 
int USART_endl(void) {
  int status = 0;
  status = USART_Transmit('\x0D');
  status = USART_Transmit('\x0A');
  return status;
}
 
int USART_Transmit(unsigned char data) {
  // Wait for empty transmit buffer
  while (!(UCSR0A & (1 << UDRE0)))
    ;
 
  // Put data into buffer, sends the data
  UDR0 = data;
 
  return 0;
}
 
// This function is a big memory nono!
int USART_SendString(char *data) {
  int status;
  int counter = 0;
  while (data[counter] != '\0') {
    if (data[counter] == '\n') {
      status = USART_Transmit('\x0D');
      status = USART_Transmit('\x0A');
    } else {
      status = USART_Transmit(data[counter]);
    }
    counter++;
  }
  return status;
}
 
int USART_Receive(void) {
  // Get and return received data from buffer
  receive_buf = UDR0;
 
  return 0;
}
 
int USART_ReceiveHandler() {
  char cmd[32] = {0};
  int cmd_count = 0;
 
  // Echo
  if (receive_buf) {
    USART_Transmit(receive_buf);
    if (receive_buf == 0x0D) {
      USART_Transmit(0x0A);
    }
 
    cmd[cmd_count] = receive_buf;
    cmd_count++;
    receive_buf = 0;
  }
 
  // CMD Handler
  if (cmd[cmd_count] == 0x0D) {
    USART_SendString(cmd);
    cmd[cmd_count] = 0;
    cmd_count = 0;
  }
 
  return 0;
}