1. Concurrency might cause ESP_ERR_TIMEOUT when calling uart_wait_tx_done
2. Concurrency might cause RTS line being de-assreted during tx transmission for rs485 mode
I'm including <hal/uart_ll.h> in my C++ application because I need to
bypass the uart driver. The inline functions in the header file fail to
compile as C++.
All of the enums need explicit casts for conversion to/from integers.
Merges https://github.com/espressif/esp-idf/pull/10106
