63 lines
2.5 KiB
C
63 lines
2.5 KiB
C
/* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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/* This library handles the USART configuration */
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#include <stdint.h> // Standard Integer Types
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#include <stdio.h> // Standard IO facilities
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#include <stdlib.h> // General utilities
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#include <avr/io.h> // AVR device-specific IO definitions
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#include "uart.h" // UART header
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#include <util/setbaud.h> // Helper macros for baud rate calculations
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/* assign input and output streams */
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FILE uart_output = FDEV_SETUP_STREAM((int (*)(char, struct __file *)) uart_putchar, NULL, _FDEV_SETUP_WRITE);
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FILE uart_input = FDEV_SETUP_STREAM(NULL, (int (*)(struct __file *)) uart_getchar, _FDEV_SETUP_READ);
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FILE uart_io = FDEV_SETUP_STREAM((int (*)(char, struct __file *)) uart_putchar, (int (*)(struct __file *)) uart_getchar, _FDEV_SETUP_RW);
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/* configure serial port */
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void uart_init(void)
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{
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UBRR0H = UBRRH_VALUE; // set baurate (calculated from BAUD)
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UBRR0L = UBRRL_VALUE; // set baurate (calculated from BAUD)
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#if USE_2X
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UCSR0A |= (1<<U2X0); // use double speed (set depending on BAUD)
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#else
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UCSR0A &= ~(1<<U2X0); // do not use double speed (set depending on BAUD)
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#endif
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UCSR0C = (1<<UCSZ01)|(1<<UCSZ00); // 8N1 bit data
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UCSR0B = (1<<RXEN0)|(1<<TXEN0); // enable RX and TX
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UCSR0B |= (1<<RXCIE0); // enable RX complete interrupt
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}
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/* put character on UART stream */
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void uart_putchar(char c, FILE *stream)
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{
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if (c == '\n') { // add carrier return before line feed. this is recommended for most UART terminals
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uart_putchar('\r', stream);
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}
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while (!(UCSR0A&(1<<UDRE0))); // wait for transmit register to empty
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UDR0 = c; // put data in transmit register
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while (!(UCSR0A&(1<<TXC0))); // wait for transmission to complete (else sleep mode can break it)
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UCSR0A |= (1<<TXC0); // clear transmit flag
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}
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/* get character from UART stream (blocking) */
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char uart_getchar(FILE *stream)
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{
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while (!(UCSR0A&(1<<RXC0))); // wait until data exists
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return UDR0;
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}
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