switch from UART to USART
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62
lib/uart.c
62
lib/uart.c
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/* 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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33
lib/uart.h
33
lib/uart.h
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@ -1,33 +0,0 @@
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/* 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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/* set tolerance to 3% to allow 115200 baudrate with 16 MHz clock, else use 9600 for default <2% */
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#define BAUD_TOL 3
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/* serial baudrate, in bits per second (with 8N1 8 bits, no parity bit, 1 stop bit settings) */
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#define BAUD 115200
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/* input & output streams */
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FILE uart_output;
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FILE uart_input;
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FILE uart_io;
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/* configure serial port */
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void uart_init(void);
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/* put character on UART stream (blocking) */
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void uart_putchar(char c, FILE *stream);
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/* get character from UART stream (blocking) */
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char uart_getchar(FILE *stream);
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50
main.c
50
main.c
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@ -26,7 +26,7 @@
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#include <avr/pgmspace.h> // Program Space Utilities
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#include <avr/sleep.h> // Power Management and Sleep Modes
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#include "uart.h" // basic UART functions
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#include "usart.h" // basic USART functions
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#include "main.h" // main definitions
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/* help strings */
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@ -46,11 +46,11 @@ PGM_P const help_table[] PROGMEM = {
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};
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/* global variables */
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char uart_in[32] = {0}; // user input from USART
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volatile uint8_t uart_in_i = 0; // how many UART characters have been input
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char usart_in[32] = {0}; // user input from USART
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volatile uint8_t usart_in_i = 0; // how many USART characters have been input
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/* flags, set in the interrupts and handled in the main program */
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volatile bool uart_flag = false; // UART input data is available
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volatile bool usart_flag = false; // USART input data is available
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/* switch off LED */
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void led_off(void)
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@ -162,16 +162,6 @@ void help(void)
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}
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}
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/* save the UART input into a string */
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ISR(USART_RX_vect) { /* UART receive interrupt */
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uart_in[uart_in_i] = getchar(); // save input
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if (uart_in_i<sizeof(uart_in)-1) { // go to next if there is space left (else overwrite last)
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uart_in_i++; // prepare for next character
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uart_in[uart_in_i] = 0; // always end the string
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}
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uart_flag = true; // notify new character is there
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}
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/* disable watchdog when booting */
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void wdt_init(void) __attribute__((naked)) __attribute__((section(".init3")));
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void wdt_init(void)
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@ -185,10 +175,10 @@ void wdt_init(void)
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/* initialize GPIO */
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void io_init(void)
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{
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/* use UART as terminal */
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uart_init();
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stdout = &uart_output;
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stdin = &uart_input;
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/* use USART as terminal */
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usart_init();
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stdout = &usart_output;
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stdin = &usart_input;
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/* gpio */
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/* LED */
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@ -203,7 +193,7 @@ void command_action()
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{
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/* split command */
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const char* delimiter = " ";
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char* word = strtok(uart_in,delimiter);
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char* word = strtok(usart_in,delimiter);
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if (!word) {
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goto error;
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}
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@ -280,27 +270,27 @@ error:
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int main(void)
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{
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uint8_t uart_out_i = 0; // how many UART input characters have been processed
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uint8_t usart_out_i = 0; // how many UART input characters have been processed
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io_init(); // initialize IOs
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printf(PSTR("welcome to the demo code\n"));
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while (true) { // endless loop for micro-controller
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while (uart_flag) { // new UART input
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uart_flag = false;
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while (uart_out_i<uart_in_i) {
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putchar(uart_in[uart_out_i++]); // print current character
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while (usart_flag) { // new UART input
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usart_flag = false;
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while (usart_out_i<usart_in_i) {
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putchar(usart_in[usart_out_i++]); // print current character
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}
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if ('\n'==uart_in[uart_in_i-1] || '\r'==uart_in[uart_in_i-1]) { // end of line detected
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if ('\r'==uart_in[uart_in_i-1]) { // be sure to print a newline (for windows and mac EOL)
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if ('\n'==usart_in[usart_in_i-1] || '\r'==usart_in[usart_in_i-1]) { // end of line detected
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if ('\r'==usart_in[usart_in_i-1]) { // be sure to print a newline (for windows and mac EOL)
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putchar('\n');
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}
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uart_in[uart_in_i-1] = 0; // remove end of line
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if (uart_in_i>1) { // ignore empty lines
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usart_in[usart_in_i-1] = 0; // remove end of line
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if (usart_in_i>1) { // ignore empty lines
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command_action(); // process command
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}
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uart_out_i = 0; // reset output
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uart_in_i = 0; // reset input
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usart_out_i = 0; // reset output
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usart_in_i = 0; // reset input
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}
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}
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/* go to sleep and wait for next interrupt */
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