Calling soft-device methods from UART/UARTE interrupt handler

[Boaz]

I have an application which receives commands from a co-processor via UART. Some commands are BLE-related such as, e.g. start-scan, stop-scan, connect, etc.

• As the UART event handler is called in the context of the UART/UARTE interrupt, is it safe to call sd_xxx() methods from this thread context?
• Alternatively, is it possible to post these events to the main thread, e.g. via a mailbox?

nRF5 SDK 11.0.0, with PCA10040 EVB

[James Yu]

You can use the scheduler library to transfer execution to the main context: infocenter.nordicsemi.com/index.jsp

[RK]

It's fine to call them from the interrupt as long as the interrupt runs at lower priority (ie a higher number) than the SVC call. So you can call the sd_* functions directly if you are running at priority 6 or 7 (the two APP LOW priorities) but not from 2 or 3 (the APP HIGH ones) as they are higher than the SVC call.

[SRA]

You're right of course, but I can think of no reason you'd ever "want" to do this. Interupts are to be jumped to a minimal amount of work done, and get back to code. I'd NEVER call something like start/stop/connect from an ISR. That's just asking for trouble. Flag or signal/mail and do it somewhere else.

[Boaz]

While I agree to the principal, most of Nordic's examples do interact with the soft device in IRQ context. I guess it depends on what a 'minimal amount of work' is. The scheduler suggested by James looks promising.