esp-idf/examples/peripherals/uart/uart_async_rxtxtasks

UART Asynchronous Example with Separate Receive and Transfer Tasks

(See the README.md file in the upper level 'examples' directory for more information about examples.)

This example demonstrates how two asynchronous tasks can use the same UART interface for communication. One can use this example to develop more complex applications for serial communication.

The example starts two FreeRTOS tasks:

1. The first task periodically transmits Hello world via the UART.
2. The second task task listens, receives and prints data from the UART.

How to use example

Hardware Required

The example can be run on any commonly available ESP32 development board. You will need a USB cable to connect the development board to a computer, and a simple one-wire cable for shorting two pins of the board.

Setup the Hardware

The RXD_PIN and TXD_PIN which are configurable in the code (by default GPIO4 and GPIO5) need to be shorted in order to receive back the same data which were sent out.

Configure the project

make menuconfig

or

idf.py menuconfig

• Set serial port under Serial Flasher Options.

Build and Flash

Build the project and flash it to the board, then run monitor tool to view serial output:

make -j4 flash monitor

or

idf.py flash monitor

(To exit the serial monitor, type Ctrl-].)

See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.

Example Output

You will receive the following repeating output from the monitoring console:

...
I (3261) TX_TASK: Wrote 11 bytes
I (4261) RX_TASK: Read 11 bytes: 'Hello world'
I (4261) RX_TASK: 0x3ffb821c   48 65 6c 6c 6f 20 77 6f  72 6c 64                 |Hello world|
...

Troubleshooting

If you do not see any output from RX_TASK then check if you have the RXD_PIN and TXD_PIN pins shorted on the board.