/* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see .
*
*/
/* Copyright (c) 2015 King Kévin */
/* this library handles the USART
* it uses the TX and RX pins
* it can be used with or without interrupts
*/
#include // Standard Integer Types
#include // Standard IO facilities
#include // General utilities
#include // AVR device-specific IO definitions
#include // Interrupts
#include // Power Management and Sleep Modes
#include "usart.h" // USART header
#include // Helper macros for baud rate calculations
/* assign input and output streams */
FILE usart_input = FDEV_SETUP_STREAM(NULL, (int (*)(struct __file *)) usart_getchar, _FDEV_SETUP_READ);
#if defined(USART_INTERRUPT) && (USART_INTERRUPT==1)
FILE usart_output = FDEV_SETUP_STREAM((int (*)(char, struct __file *)) usart_putchar_nonblocking, NULL, _FDEV_SETUP_WRITE);
FILE usart_io = FDEV_SETUP_STREAM((int (*)(char, struct __file *)) usart_putchar_nonblocking, (int (*)(struct __file *)) usart_getchar, _FDEV_SETUP_RW);
#else
FILE usart_output = FDEV_SETUP_STREAM((int (*)(char, struct __file *)) usart_putchar_blocking, NULL, _FDEV_SETUP_WRITE);
FILE usart_io = FDEV_SETUP_STREAM((int (*)(char, struct __file *)) usart_putchar_blocking, (int (*)(struct __file *)) usart_getchar, _FDEV_SETUP_RW);
#endif
#if defined(USART_INTERRUPT) && (USART_INTERRUPT==1)
/* input and output ring buffer, indexes, and available memory */
uint8_t rx_buffer[32] = {0};
volatile uint8_t rx_i = 0;
volatile uint8_t rx_used = 0;
uint8_t tx_buffer[32] = {0};
volatile uint8_t tx_i = 0;
volatile uint8_t tx_used = 0;
/* show the user how much received data is ready */
volatile uint8_t usart_incoming = 0; // same as rx_used, but since the user can write this variable we don't rely on it
#endif
/* configure USART serial port */
void usart_init(void)
{
UBRR0H = UBRRH_VALUE; // set baurate (calculated from BAUD)
UBRR0L = UBRRL_VALUE; // set baurate (calculated from BAUD)
#if USE_2X
UCSR0A |= (1<=sizeof(rx_buffer)) {
return;
}
cli();
rx_buffer[(rx_i+rx_used)%sizeof(rx_buffer)] = UDR0; // put character in buffer
rx_used++; // update used buffer
usart_incoming = rx_used; // update available data
sei();
}
/* put character on USART stream (non-blocking using a buffer) */
void usart_putchar_nonblocking(char c, FILE *stream)
{
if (c == '\n') { // add carrier return before line feed. this is recommended for most UART terminals
usart_putchar_nonblocking('\r', stream);
}
if (UCSR0A&(1<=sizeof(tx_buffer)) {
set_sleep_mode(SLEEP_MODE_IDLE);
sleep_mode();
}
cli();
tx_buffer[(tx_i+tx_used)%sizeof(tx_buffer)] = c; // put character in buffer
tx_used++; // update used buffer
sei();
}
}
ISR(USART_UDRE_vect) { // USART transmit register interrupt
if (!tx_used) { // no data in the buffer to transmit
return;
}
UDR0 = tx_buffer[tx_i]; // put data in transmit register
tx_i = (tx_i+1)%sizeof(rx_buffer); // update location on buffer
tx_used--; // update used size
}
#endif