140 lines
6.4 KiB
C
140 lines
6.4 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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/** library for receiving NMEA-0183 like messages over a Bluetooth module (code)
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* @file radio_bluetooth.c
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* @author King Kévin <kingkevin@cuvoodoo.info>
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* @date 2017
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* @note peripherals used: USART @ref radio_bluetooth_usart
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*/
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/* standard libraries */
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#include <stdint.h> // standard integer types
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#include <stdio.h> // standard I/O facilities
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#include <stdlib.h> // general utilities
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#include <string.h> // string utilities
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/* STM32 (including CM3) libraries */
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#include <libopencm3/stm32/rcc.h> // real-time control clock library
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#include <libopencm3/stm32/gpio.h> // general purpose input output library
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#include <libopencm3/stm32/usart.h> // universal synchronous asynchronous receiver transmitter library
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#include <libopencm3/cm3/nvic.h> // interrupt handler
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#include <libopencmsis/core_cm3.h> // Cortex M3 utilities
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#include "radio_bluetooth.h" // forumslader header and definitions
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#include "global.h" // common methods
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/** @defgroup radio_bluetooth_usart USART peripheral used for communication with the Bluetooth module
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* @{
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*/
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#define RADIO_BLUETOOTH_USART 2 /**< USART peripheral */
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/** @} */
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#define RADIO_BLUETOOTH_BAUDRATE 115200 /**< USART baud rate for the Bluetooth communication, in bits per second (with 8N1 8 bits, no parity bit, 1 stop bit settings) */
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static volatile char rx_buffer[82] = {0}; /**< buffer for received data (82 chars is the maximum NMEA-0183 message length) */
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static volatile uint8_t rx_buffer_i = 0; /**< current position of read received data */
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static volatile char tx_buffer[82] = {0}; /**< buffer to transmit data */
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static volatile uint8_t tx_buffer_i = 0; /**< number or remaining characters to transmit */
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volatile bool radio_bluetooth_received = false;
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volatile bool radio_bluetooth_transmitted = false;
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volatile char radio_bluetooth_message[82+1] = {0};
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void radio_bluetooth_setup(void)
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{
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/* enable USART I/O peripheral */
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rcc_periph_clock_enable(USART_PORT_RCC(RADIO_BLUETOOTH_USART)); // enable clock for USART port peripheral
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rcc_periph_clock_enable(USART_RCC(RADIO_BLUETOOTH_USART)); // enable clock for USART peripheral
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rcc_periph_clock_enable(RCC_AFIO); // enable pin alternate function (USART)
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gpio_set_mode(USART_PORT(RADIO_BLUETOOTH_USART), GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, USART_PIN_TX(RADIO_BLUETOOTH_USART)); // setup GPIO pin USART transmit
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gpio_set_mode(USART_PORT(RADIO_BLUETOOTH_USART), GPIO_MODE_INPUT, GPIO_CNF_INPUT_PULL_UPDOWN, USART_PIN_RX(RADIO_BLUETOOTH_USART)); // setup GPIO pin USART receive
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gpio_set(USART_PORT(RADIO_BLUETOOTH_USART), USART_PIN_RX(RADIO_BLUETOOTH_USART)); // pull up to avoid noise when not connected
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/* setup USART parameters */
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usart_set_baudrate(USART(RADIO_BLUETOOTH_USART), RADIO_BLUETOOTH_BAUDRATE); // set baud rate
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usart_set_databits(USART(RADIO_BLUETOOTH_USART), 8); // set data bits
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usart_set_stopbits(USART(RADIO_BLUETOOTH_USART), USART_STOPBITS_1); // set stop bit
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usart_set_mode(USART(RADIO_BLUETOOTH_USART), USART_MODE_TX_RX); // enable transmit and receive
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usart_set_parity(USART(RADIO_BLUETOOTH_USART), USART_PARITY_NONE); // set parity
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usart_set_flow_control(USART(RADIO_BLUETOOTH_USART), USART_FLOWCONTROL_NONE); // set flow control
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nvic_enable_irq(USART_IRQ(RADIO_BLUETOOTH_USART)); // enable the USART interrupt
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usart_enable_rx_interrupt(USART(RADIO_BLUETOOTH_USART)); // enable receive interrupt
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usart_enable(USART(RADIO_BLUETOOTH_USART)); // enable USART
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/* reset buffer states */
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radio_bluetooth_received = false;
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rx_buffer_i = 0;
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radio_bluetooth_transmitted = false;
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tx_buffer_i = 0;
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}
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bool radio_bluetooth_transmit(const char* message)
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{
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if (strlen(message)>LENGTH(tx_buffer)) { // message to transmit is too long
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return false;
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}
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while (tx_buffer_i) { // idle until buffer is empty
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__WFI(); // sleep until interrupt
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}
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for (uint8_t i=0; i<strlen(message); i++) { // copy message to transmit to internal buffer
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tx_buffer[strlen(message)-1-i] = message[i]; // copy in reverse orders to we can count remaining characters to transmit
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}
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tx_buffer_i = strlen(message); // save number of characters to transmit
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radio_bluetooth_transmitted = false; // reset transmit flag
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usart_enable_tx_interrupt(USART(RADIO_BLUETOOTH_USART)); // enable transmit interrupt
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return true;
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}
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/** USART interrupt service routine called when data has been received */
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void USART_ISR(RADIO_BLUETOOTH_USART)(void)
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{
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if (usart_get_flag(USART(RADIO_BLUETOOTH_USART), USART_SR_RXNE)) { // data has been received
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char c = usart_recv(USART(RADIO_BLUETOOTH_USART)); // put character in buffer (and clear flag)
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// only save data if there is space in the buffer
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if (rx_buffer_i<LENGTH(rx_buffer)) {
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rx_buffer[rx_buffer_i++] = c;
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}
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if ('\n'==c) { // end of message received
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// verify if the message is correctly formatted
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if (rx_buffer_i<1 || '$'!=rx_buffer[0]) {
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goto malformatted;
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} else if (rx_buffer_i<2 || '\r'!=rx_buffer[rx_buffer_i-2]) {
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goto malformatted;
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}
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// copy message to user
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for (uint8_t i = 0; i < rx_buffer_i && i < LENGTH(radio_bluetooth_message); i++) {
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radio_bluetooth_message[i] = rx_buffer[i];
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}
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// terminate string
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if (rx_buffer_i<LENGTH(radio_bluetooth_message)) {
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radio_bluetooth_message[rx_buffer_i] = '\0';
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} else {
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radio_bluetooth_message[LENGTH(radio_bluetooth_message)-1] = '\0';
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}
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radio_bluetooth_received = true; // notify user a message is available
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malformatted:
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rx_buffer_i = 0; // reset buffer
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}
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}
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if (usart_get_flag(USART(RADIO_BLUETOOTH_USART), USART_SR_TXE) && tx_buffer_i) { // data has been transmitted
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usart_send(USART(RADIO_BLUETOOTH_USART),tx_buffer[--tx_buffer_i]); // put data in transmit register
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if (0==tx_buffer_i) { // no data in the buffer to transmit
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usart_disable_tx_interrupt(USART(RADIO_BLUETOOTH_USART)); // disable transmit interrupt
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radio_bluetooth_transmitted = true; // notify user
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}
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}
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}
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