ef5dc73f6f
An existing UART driver does not support RS485 half duplex mode. This task adds this functionality to ESP_IDF UART driver. driver/uart.c/h: updated to add support of RS485 half duplex mode examples/peripherals/uart_echo_rs485/main/rs485_example.c: added test example components/driver/test/test_uart.c: added test of RS485 half duplex mode docs/en/api-reference/peripherals/uart.rst: updated documentation test_uart.c: suppress GCC warnings about discarded const qualifiers uart.rst: remove sphinx warning - "Duplicate explicit target name" simple change in uart.h file update (test_uart.c) after rebase from master update uart.rst, uart.c, rs485_example.c Update example description in file Readme.md update uart.c/h, uart.rst, test_uart.c according to review results update uart.h (uart_set_rx_timeout() description test_uart.c remove ignore tag uart.c/h: fix param errors test_uart.c: Remove GCC warning supress uart.rst: fix the notes rs485_example.c: fix output The tests are completed using RS485 adapters hardware connected to two ESP32 WROVER KITs. TW#13812 Closes https://github.com/espressif/esp-idf/pull/667 Closes https://github.com/espressif/esp-idf/pull/1006
127 lines
4 KiB
C
127 lines
4 KiB
C
/* Uart Events 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 <string.h>
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#include <stdlib.h>
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#include "freertos/FreeRTOS.h"
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#include "freertos/task.h"
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#include "esp_system.h"
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#include "nvs_flash.h"
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#include "driver/uart.h"
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#include "freertos/queue.h"
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#include "esp_log.h"
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#include "soc/uart_struct.h"
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/**
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* This is a example example which echos any data it receives on UART back to the sender.
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*
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* - port: UART2
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* - rx buffer: on
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* - tx buffer: off
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* - flow control: off
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*
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* This example has been tested on a 3 node RS485 Serial Bus
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*
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*/
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// Note: UART2 default pins IO16, IO17 do not work on ESP32-WROVER module
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// because these pins connected to PSRAM
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#define ECHO_TEST_TXD (23)
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#define ECHO_TEST_RXD (22)
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// RTS for RS485 Half-Duplex Mode manages DE/~RE
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#define ECHO_TEST_RTS (18)
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// CTS is not used in RS485 Half-Duplex Mode
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#define ECHO_TEST_CTS UART_PIN_NO_CHANGE
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#define BUF_SIZE (127)
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#define BAUD_RATE (115200)
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// Read packet timeout
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#define PACKET_READ_TICS (100 / portTICK_RATE_MS)
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#define ECHO_TASK_STACK_SIZE (2048)
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#define ECHO_TASK_PRIO (10)
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#define ECHO_UART_PORT (UART_NUM_2)
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static const char *TAG = "RS485_ECHO_APP";
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// An example of echo test with hardware flow control on UART
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static void echo_task()
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{
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const int uart_num = ECHO_UART_PORT;
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uart_config_t uart_config = {
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.baud_rate = BAUD_RATE,
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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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.rx_flow_ctrl_thresh = 122,
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};
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// Set UART log level
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esp_log_level_set(TAG, ESP_LOG_INFO);
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ESP_LOGI(TAG, "Start RS485 application test and configure UART.");
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// Configure UART parameters
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uart_param_config(uart_num, &uart_config);
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ESP_LOGI(TAG, "UART set pins, mode and install driver.");
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// Set UART1 pins(TX: IO23, RX: I022, RTS: IO18, CTS: IO19)
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uart_set_pin(uart_num, ECHO_TEST_TXD, ECHO_TEST_RXD, ECHO_TEST_RTS, ECHO_TEST_CTS);
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// Install UART driver (we don't need an event queue here)
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// In this example we don't even use a buffer for sending data.
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uart_driver_install(uart_num, BUF_SIZE * 2, 0, 0, NULL, 0);
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// Set RS485 half duplex mode
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uart_set_mode(uart_num, UART_MODE_RS485_HALF_DUPLEX);
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// Allocate buffers for UART
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uint8_t* data = (uint8_t*) malloc(BUF_SIZE);
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ESP_LOGI(TAG, "UART start recieve loop.\r\n");
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uart_write_bytes(uart_num, "Start RS485 UART test.\r\n", 24);
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while(1) {
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//Read data from UART
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int len = uart_read_bytes(uart_num, data, BUF_SIZE, PACKET_READ_TICS);
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//Write data back to UART
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if (len > 0) {
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uart_write_bytes(uart_num, "\r\n", 2);
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char prefix[] = "RS485 Received: [";
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uart_write_bytes(uart_num, prefix, (sizeof(prefix) - 1));
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ESP_LOGI(TAG, "Received %u bytes:", len);
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printf("[ ");
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for (int i = 0; i < len; i++) {
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printf("0x%.2X ", (uint8_t)data[i]);
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uart_write_bytes(uart_num, (const char*)&data[i], 1);
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// Add a Newline character if you get a return charater from paste (Paste tests multibyte receipt/buffer)
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if (data[i] == '\r') {
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uart_write_bytes(uart_num, "\n", 1);
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}
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}
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printf("] \n");
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uart_write_bytes(uart_num, "]\r\n", 3);
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} else {
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// Echo a "." to show we are alive while we wait for input
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uart_write_bytes(uart_num, ".", 1);
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}
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}
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}
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void app_main()
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{
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//A uart read/write example without event queue;
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xTaskCreate(echo_task, "uart_echo_task", ECHO_TASK_STACK_SIZE, NULL, ECHO_TASK_PRIO, NULL);
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}
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