kopia lustrzana https://github.com/espressif/esp-idf
99 wiersze
2.9 KiB
C
99 wiersze
2.9 KiB
C
/* UART Select Example
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This example code is in the Public Domain (or CC0 licensed, at your option.)
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Unless required by applicable law or agreed to in writing, this
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software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
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CONDITIONS OF ANY KIND, either express or implied.
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*/
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#include <stdio.h>
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#include <sys/fcntl.h>
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#include <sys/errno.h>
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#include <sys/unistd.h>
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#include <sys/select.h>
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#include "freertos/FreeRTOS.h"
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#include "freertos/task.h"
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#include "esp_log.h"
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#include "driver/uart_vfs.h"
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#include "driver/uart.h"
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static const char* TAG = "uart_select_example";
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static void uart_select_task(void *arg)
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{
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if (uart_driver_install(UART_NUM_0, 2 * 1024, 0, 0, NULL, 0) != ESP_OK) {
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ESP_LOGE(TAG, "Driver installation failed");
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vTaskDelete(NULL);
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}
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uart_config_t uart_config = {
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.baud_rate = 115200,
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.data_bits = UART_DATA_8_BITS,
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.parity = UART_PARITY_DISABLE,
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.stop_bits = UART_STOP_BITS_1,
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.flow_ctrl = UART_HW_FLOWCTRL_DISABLE,
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.source_clk = UART_SCLK_DEFAULT,
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};
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uart_param_config(UART_NUM_0, &uart_config);
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while (1) {
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int fd;
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if ((fd = open("/dev/uart/0", O_RDWR)) == -1) {
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ESP_LOGE(TAG, "Cannot open UART");
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vTaskDelay(5000 / portTICK_PERIOD_MS);
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continue;
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}
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// We have a driver now installed so set up the read/write functions to use driver also.
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uart_vfs_dev_use_driver(0);
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while (1) {
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int s;
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fd_set rfds;
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struct timeval tv = {
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.tv_sec = 5,
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.tv_usec = 0,
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};
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FD_ZERO(&rfds);
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FD_SET(fd, &rfds);
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s = select(fd + 1, &rfds, NULL, NULL, &tv);
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if (s < 0) {
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ESP_LOGE(TAG, "Select failed: errno %d", errno);
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break;
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} else if (s == 0) {
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ESP_LOGI(TAG, "Timeout has been reached and nothing has been received");
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} else {
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if (FD_ISSET(fd, &rfds)) {
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char buf;
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if (read(fd, &buf, 1) > 0) {
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ESP_LOGI(TAG, "Received: %c", buf);
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// Note: Only one character was read even the buffer contains more. The other characters will
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// be read one-by-one by subsequent calls to select() which will then return immediately
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// without timeout.
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} else {
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ESP_LOGE(TAG, "UART read error");
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break;
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}
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} else {
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ESP_LOGE(TAG, "No FD has been set in select()");
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break;
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}
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}
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}
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close(fd);
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}
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vTaskDelete(NULL);
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}
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void app_main(void)
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{
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xTaskCreate(uart_select_task, "uart_select_task", 4 * 1024, NULL, 5, NULL);
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}
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