RE: Using ZBus with ISRs

Håkon Alseth — Mon, 29 Apr 2024 14:00:19 GMT

Hi,

Always happy to help out.

Hope you have a wonderful day!

Kind regards,

Håkon

RE: Using ZBus with ISRs

saiff — Mon, 29 Apr 2024 12:23:15 GMT

Hi Hakon,

Thanks for your response, indeed apparently i was checking an older version of the documentation, thanks for clearing that up.

Kind regards,

RE: Using ZBus with ISRs

Håkon Alseth — Mon, 29 Apr 2024 12:07:58 GMT

Hi,

Not sure which version of ncs that holds this specific docs sentence, but we base our sdk-zephyr on upstream-zephyr, so the docs will be similar.

For example, here's the upstream zephyr v3.5.0 docs:

https://docs.zephyrproject.org/3.5.0/services/zbus/index.html#concepts

Is it this sentence you're wondering about? This sentence is removed from the docs in newer zephyr version(s) (v3.6.99 and newer)

However, it cannot run inside Interrupt Service Routines (ISR) because it uses mutexes to control channel access, and mutexes cannot work appropriately inside ISRs.

Mutex'es cannot be taken from ISR context, and the same goes for anything that has a timeout that is non-zero (ie. needs to be K_NO_WAIT).

This is also notified on the specific API's as well, for instance here:

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/zephyr/services/zbus/index.html#publishing-to-a-channel

Kind regards,

Håkon