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esp32, UART sample (UART2)
/* Uart Events Example
This example code is in the Public Domain (or CC0 licensed, at your option.)
Unless required by applicable law or agreed to in writing, this
software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
CONDITIONS OF ANY KIND, either express or implied.
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "esp_system.h"
#include "nvs_flash.h"
#include "driver/uart.h"
#include "freertos/queue.h"
#include "esp_log.h"
#include "soc/uart_struct.h"
* This is a example exaple which echos any data it receives on UART1 back to the sender, with hardware flow control
* turned on. It does not use UART driver event queue.
* - port: UART1
* - rx buffer: on
* - tx buffer: off
* - flow control: on
* - event queue: off
* - pin assignment: txd(io4), rxd(io5), rts(18), cts(19)
//#define ECHO_TEST_TXD (4)
//#define ECHO_TEST_RXD (5)
#define ECHO_TEST_TXD (16)
#define ECHO_TEST_RXD (17)
#define ECHO_TEST_RTS (18)
#define ECHO_TEST_CTS (19)
#define BUF_SIZE (1024)
//an example of echo test with hardware flow control on UART1
static void echo_task()
// const int uart_num = UART_NUM_1;
const int uart_num = UART_NUM_2;
uart_config_t uart_config = {
.baud_rate = 115200,
.data_bits = UART_DATA_8_BITS,
.stop_bits = UART_STOP_BITS_1,
.rx_flow_ctrl_thresh = 122,
//Configure UART1 parameters
uart_param_config(uart_num, &uart_config);
//Set UART1 pins(TX: IO4, RX: I05, RTS: IO18, CTS: IO19)
//Install UART driver (we don't need an event queue here)
//In this example we don't even use a buffer for sending data.
uart_driver_install(uart_num, BUF_SIZE * 2, 0, 0, NULL, 0);
uint8_t* data = (uint8_t*) malloc(BUF_SIZE);
while(1) {
//Read data from UART
int len = uart_read_bytes(uart_num, data, BUF_SIZE, 20 / portTICK_RATE_MS);
//Write data back to UART
uart_write_bytes(uart_num, (const char*) data, len);
void app_main()
//A uart read/write example without event queue;
xTaskCreate(echo_task, "uart_echo_task", 1024, NULL, 10, NULL);

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commented May 22, 2018

How to control cts and rts pins while sending large data

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