Feature Request: function call when there is input available on stdin #547

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opened 2021-08-25 12:11:28 -05:00 by carlk3 · 2 comments

carlk3 commented

2021-08-25 12:11:28 -05:00

(Migrated from github.com)

I'm working with the FreeRTOS port, and finding it difficult to use standard input (stdin) from a terminal. Polling stdin with getchar_timeout_us() either stalls or burns up all the CPU cycles, which doesn't play well in a multitasking OS. I can see how to make a UART-connected terminal work in an interrupt-driven fashion in pico-examples/uart/uart_advanced. However, I would like to maintain the ability to change the destination for stdin and stdout using CMake directives, with input/output directed to UART or USB CDC.

How about an enhancement to Serial input and output on Raspberry Pi Pico that would make it possible to register a callback or something that could receive keystrokes from a terminal as they are typed, asynchronously, regardless of whether serial input (stdin) and output (stdout) are directed to either serial UART or to USB CDC (USB serial)?

I'm working with the FreeRTOS port, and finding it difficult to use standard input (stdin) from a terminal. Polling stdin with `getchar_timeout_us()` either stalls or burns up all the CPU cycles, which doesn't play well in a multitasking OS. I can see how to make a UART-connected terminal work in an interrupt-driven fashion in `pico-examples/uart/uart_advanced`. However, I would like to maintain the ability to change the destination for stdin and stdout using CMake directives, with input/output directed to UART or USB CDC. How about an enhancement to *Serial input and output on Raspberry Pi Pico* that would make it possible to register a callback or something that could receive keystrokes from a terminal as they are typed, asynchronously, regardless of whether serial input (stdin) and output (stdout) are directed to either serial UART or to USB CDC (USB serial)?

kilograham commented

2021-10-07 18:34:56 -05:00

(Migrated from github.com)

the stdio abstraction is a bit messy as is, so i don't want to pile on any more for 1.2.1 release - try to improve it in a future release when there is more time

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