k_sem_take failed UART interrupts Bluetooth

RE: k_sem_take failed UART interrupts Bluetooth

Einarh — Thu, 19 May 2022 14:28:35 GMT

Hello

Running BLE and UART in parallel is indeed a common issue, as BLE tasks need to run with high priority to comply with the strict timing requirements of the BLE specification, which can easily interfere with your UART operations. I would recommend that you use the UARTE peripheral, which has EasyDMA support that allows you to send/receive data directly through RAM while BLE uses the CPU:

https://infocenter.nordicsemi.com/index.jsp?topic=%2Fps_nrf52840%2Fuarte.html

http://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrfx/drivers/uarte/driver.html

This should solve your problem, and even gives you something cool to write about in your thesis.

This other guy is technically correct that it's good practice to keep blocking code out of your callback functions, and I'd recommend reading up on semaphores as a way to signal between threads, but I believe UARTE is a better solution to your issue.

Best regards,

Einar

RE: k_sem_take failed UART interrupts Bluetooth

PasN — Thu, 19 May 2022 06:27:59 GMT

Hello Turbo J, thank you for your quick answer. I understand what you mean, but I don't know how to realize it in code. Like I said, Im not experienced enough with Zephyr to find a solution by myself.

RE: k_sem_take failed UART interrupts Bluetooth

Turbo J — Wed, 18 May 2022 13:48:27 GMT

The callback from the uart function runs from an interrupt handler, which disallows a lot of OS-related functions. To keep stuff simple: You cannot call anything that waits in an interrupt handler.

Solution: Use one of the many ways that Zephyr provides to communicate between the uart callback function and another thread/function/ work queue. There you can wait and use the bt_le_xxx() calls.