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/*
* The MIT License (MIT)
*
* Copyright (c) 2015 Matthias P. Braendli
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include "common.h"
#include "usart.h"
#include <stm32f4xx.h>
#include <stm32f4xx_usart.h>
#include <stm32f4xx_conf.h>
#include "FreeRTOS.h"
#include "task.h"
#include "queue.h"
// USART 3 on PD8 and PD9
const uint16_t GPIOD_PIN_USART3_TX = GPIO_Pin_8;
const uint16_t GPIOD_PIN_USART3_RX = GPIO_Pin_9;
// The ISR writes into this buffer
static char nmea_sentence[MAX_NMEA_SENTENCE_LEN];
static int nmea_sentence_last_written = 0;
// Once a completed NMEA sentence is received in the ISR,
// it is appended to this queue
static QueueHandle_t usart_nmea_queue;
void usart_init()
{
usart_nmea_queue = xQueueCreate(15, MAX_NMEA_SENTENCE_LEN);
if (usart_nmea_queue == 0) {
while(1); /* fatal error */
}
// Setup GPIO D and connect to USART 3
RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART3, ENABLE);
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);
GPIO_InitTypeDef GPIO_InitStruct;
GPIO_InitStruct.GPIO_Pin = GPIOD_PIN_USART3_RX | GPIOD_PIN_USART3_TX;
GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;
GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_UP;
GPIO_Init(GPIOD, &GPIO_InitStruct);
GPIO_PinAFConfig(GPIOD, GPIO_PinSource8, GPIO_AF_USART3);
GPIO_PinAFConfig(GPIOD, GPIO_PinSource9, GPIO_AF_USART3);
// Setup USART3 for 9600,8,N,1
USART_InitTypeDef USART_InitStruct;
USART_InitStruct.USART_BaudRate = 9600;
USART_InitStruct.USART_WordLength = USART_WordLength_8b;
USART_InitStruct.USART_StopBits = USART_StopBits_1;
USART_InitStruct.USART_Parity = USART_Parity_No;
USART_InitStruct.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
USART_InitStruct.USART_Mode = USART_Mode_Tx | USART_Mode_Rx;
USART_Init(USART3, &USART_InitStruct);
// enable the USART3 receive interrupt
USART_ITConfig(USART3, USART_IT_RXNE, ENABLE);
NVIC_InitTypeDef NVIC_InitStructure;
NVIC_InitStructure.NVIC_IRQChannel = USART3_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 6;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
NVIC_SetPriority(USART3_IRQn, 6);
// finally this enables the complete USART3 peripheral
USART_Cmd(USART3, ENABLE);
}
void usart_puts(const char* str)
{
while(*str) {
// wait until data register is empty
while ( !(USART3->SR & 0x00000040) );
USART_SendData(USART3, *str);
str++;
}
}
int usart_get_nmea_sentence(char* nmea)
{
return xQueueReceive(usart_nmea_queue, nmea, portMAX_DELAY);
}
static void usart_clear_nmea_buffer(void)
{
for (int i = 0; i < MAX_NMEA_SENTENCE_LEN; i++) {
nmea_sentence[i] = '\0';
}
nmea_sentence_last_written = 0;
}
void USART3_IRQHandler(void)
{
if (USART_GetITStatus(USART3, USART_IT_RXNE)) {
char t = USART3->DR;
if (nmea_sentence_last_written == 0) {
if (t == '$') {
// Likely new start of sentence
nmea_sentence[nmea_sentence_last_written] = t;
nmea_sentence_last_written++;
}
}
else if (nmea_sentence_last_written < MAX_NMEA_SENTENCE_LEN) {
nmea_sentence[nmea_sentence_last_written] = t;
nmea_sentence_last_written++;
if (t == '\n') {
int success = xQueueSendToBackFromISR(
usart_nmea_queue,
nmea_sentence,
NULL);
if (success == pdFALSE) {
trigger_fault(FAULT_SOURCE_USART);
}
usart_clear_nmea_buffer();
}
}
else {
// Buffer overrun without a meaningful NMEA message.
usart_clear_nmea_buffer();
}
}
}
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