OVMS3-idf/examples/protocols/sockets/tcp_client/README.md

TCP Client example

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

The application creates a TCP socket and tries to connect to the server with predefined IP address and port number. When a connection is successfully established, the application sends message and waits for the answer. After the server's reply, application prints received reply as ASCII text, waits for 2 seconds and sends another message.

How to use example

In order to create TCP server that communicates with TCP Client example, choose one of the following options.

There are many host-side tools which can be used to interact with the UDP/TCP server/client. One command line tool is netcat which can send and receive many kinds of packets. Note: please replace 192.168.0.167 3333 with desired IPV4/IPV6 address (displayed in monitor console) and port number in the following command.

In addition to those tools, simple Python scripts can be found under sockets/scripts directory. Every script is designed to interact with one of the examples.

TCP server using netcat

nc -l 192.168.0.167 3333

Python scripts

Script example_test.py could be used as a counter part to the tcp-client project, ip protocol name (IPv4 or IPv6) shall be stated as argument. Example:

python example_test.py IPv4

Note that this script is used in automated tests, as well, so the IDF test framework packages need to be imported; please add $IDF_PATH/tools/ci/python_packages to PYTHONPATH.

Hardware Required

This example can be run on any commonly available ESP32 development board.

Configure the project

idf.py menuconfig

Set following parameters under Example Configuration Options:

• Set IP version of example to be IPV4 or IPV6.

• Set IPV4 Address in case your chose IP version IPV4 above.

• Set IPV6 Address in case your chose IP version IPV6 above.

• Set Port number that represents remote port the example will connect to.

Configure Wi-Fi or Ethernet under "Example Connection Configuration" menu. See "Establishing Wi-Fi or Ethernet Connection" section in examples/protocols/README.md for more details.

Build and Flash

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

idf.py -p PORT 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.

Troubleshooting

Start server first, to receive data sent from the client (application).