esp-idf/examples/peripherals/uart_select/README.md

UART Select Example

The UART select example is for demonstrating the use of select() for synchronous I/O multiplexing on the UART interface. The example waits for a character from UART using select() until a blocking read without delay or a successful non-blocking read is possible.

Please note that the same result can be achieved by using uart_read_bytes() but the use of select() allows to use it together with other virtual file system (VFS) drivers, e.g. LWIP sockets. For a more comprehensive example please refer to system/select.

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