1 /* Uart Events Example
2
3 This example code is in the Public Domain (or CC0 licensed, at your option.)
4
5 Unless required by applicable law or agreed to in writing, this
6 software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
7 CONDITIONS OF ANY KIND, either express or implied.
8 */
9 #include <stdio.h>
10 #include <string.h>
11 #include <stdlib.h>
12 #include "freertos/FreeRTOS.h"
13 #include "freertos/task.h"
14 #include "esp_system.h"
15 #include "nvs_flash.h"
16 #include "driver/uart.h"
17 #include "freertos/queue.h"
18 #include "esp_log.h"
19 #include "sdkconfig.h"
20
21 /**
22 * This is a example which echos any data it receives on UART back to the sender using RS485 interface in half duplex mode.
23 */
24 #define TAG "RS485_ECHO_APP"
25
26 // Note: Some pins on target chip cannot be assigned for UART communication.
27 // Please refer to documentation for selected board and target to configure pins using Kconfig.
28 #define ECHO_TEST_TXD (CONFIG_ECHO_UART_TXD)
29 #define ECHO_TEST_RXD (CONFIG_ECHO_UART_RXD)
30
31 // RTS for RS485 Half-Duplex Mode manages DE/~RE
32 #define ECHO_TEST_RTS (CONFIG_ECHO_UART_RTS)
33
34 // CTS is not used in RS485 Half-Duplex Mode
35 #define ECHO_TEST_CTS (UART_PIN_NO_CHANGE)
36
37 #define BUF_SIZE (127)
38 #define BAUD_RATE (CONFIG_ECHO_UART_BAUD_RATE)
39
40 // Read packet timeout
41 #define PACKET_READ_TICS (100 / portTICK_RATE_MS)
42 #define ECHO_TASK_STACK_SIZE (2048)
43 #define ECHO_TASK_PRIO (10)
44 #define ECHO_UART_PORT (CONFIG_ECHO_UART_PORT_NUM)
45
46 // Timeout threshold for UART = number of symbols (~10 tics) with unchanged state on receive pin
47 #define ECHO_READ_TOUT (3) // 3.5T * 8 = 28 ticks, TOUT=3 -> ~24..33 ticks
48
echo_send(const int port,const char * str,uint8_t length)49 static void echo_send(const int port, const char* str, uint8_t length)
50 {
51 if (uart_write_bytes(port, str, length) != length) {
52 ESP_LOGE(TAG, "Send data critical failure.");
53 // add your code to handle sending failure here
54 abort();
55 }
56 }
57
58 // An example of echo test with hardware flow control on UART
echo_task(void * arg)59 static void echo_task(void *arg)
60 {
61 const int uart_num = ECHO_UART_PORT;
62 uart_config_t uart_config = {
63 .baud_rate = BAUD_RATE,
64 .data_bits = UART_DATA_8_BITS,
65 .parity = UART_PARITY_DISABLE,
66 .stop_bits = UART_STOP_BITS_1,
67 .flow_ctrl = UART_HW_FLOWCTRL_DISABLE,
68 .rx_flow_ctrl_thresh = 122,
69 .source_clk = UART_SCLK_APB,
70 };
71
72 // Set UART log level
73 esp_log_level_set(TAG, ESP_LOG_INFO);
74
75 ESP_LOGI(TAG, "Start RS485 application test and configure UART.");
76
77 // Install UART driver (we don't need an event queue here)
78 // In this example we don't even use a buffer for sending data.
79 ESP_ERROR_CHECK(uart_driver_install(uart_num, BUF_SIZE * 2, 0, 0, NULL, 0));
80
81 // Configure UART parameters
82 ESP_ERROR_CHECK(uart_param_config(uart_num, &uart_config));
83
84 ESP_LOGI(TAG, "UART set pins, mode and install driver.");
85
86 // Set UART pins as per KConfig settings
87 ESP_ERROR_CHECK(uart_set_pin(uart_num, ECHO_TEST_TXD, ECHO_TEST_RXD, ECHO_TEST_RTS, ECHO_TEST_CTS));
88
89 // Set RS485 half duplex mode
90 ESP_ERROR_CHECK(uart_set_mode(uart_num, UART_MODE_RS485_HALF_DUPLEX));
91
92 // Set read timeout of UART TOUT feature
93 ESP_ERROR_CHECK(uart_set_rx_timeout(uart_num, ECHO_READ_TOUT));
94
95 // Allocate buffers for UART
96 uint8_t* data = (uint8_t*) malloc(BUF_SIZE);
97
98 ESP_LOGI(TAG, "UART start recieve loop.\r\n");
99 echo_send(uart_num, "Start RS485 UART test.\r\n", 24);
100
101 while(1) {
102 //Read data from UART
103 int len = uart_read_bytes(uart_num, data, BUF_SIZE, PACKET_READ_TICS);
104
105 //Write data back to UART
106 if (len > 0) {
107 echo_send(uart_num, "\r\n", 2);
108 char prefix[] = "RS485 Received: [";
109 echo_send(uart_num, prefix, (sizeof(prefix) - 1));
110 ESP_LOGI(TAG, "Received %u bytes:", len);
111 printf("[ ");
112 for (int i = 0; i < len; i++) {
113 printf("0x%.2X ", (uint8_t)data[i]);
114 echo_send(uart_num, (const char*)&data[i], 1);
115 // Add a Newline character if you get a return charater from paste (Paste tests multibyte receipt/buffer)
116 if (data[i] == '\r') {
117 echo_send(uart_num, "\n", 1);
118 }
119 }
120 printf("] \n");
121 echo_send(uart_num, "]\r\n", 3);
122 } else {
123 // Echo a "." to show we are alive while we wait for input
124 echo_send(uart_num, ".", 1);
125 ESP_ERROR_CHECK(uart_wait_tx_done(uart_num, 10));
126 }
127 }
128 vTaskDelete(NULL);
129 }
130
app_main(void)131 void app_main(void)
132 {
133 //A uart read/write example without event queue;
134 xTaskCreate(echo_task, "uart_echo_task", ECHO_TASK_STACK_SIZE, NULL, ECHO_TASK_PRIO, NULL);
135 }
136
