I2C Read Register during GPIOTE callback

[Nick_RA]

The application here is reading a Manchester stream on a GPIO. which comes from a MAX41473 radio IC.

Decoding is working fine using GPIOTE, timers & PPI to time & decode the data stream. But when I have detected the signature of a valid packet I need to read a I2C register on the MAX41473 in order to get the RSSI value from the radio with as little latency as possible - otherwise I could be reading the RSSI when the packet has finished. Getting the packet RSSI is a must-have for this application.

If I call i2c_reg_read_byte() during the GPIO callback it fails with a return code of 251. If for example I set a flag and call the same from main() it works.

Is this an IRQ priority issue, stack levels or something else?

Using nRF54L15, IO pin P1.05 and comms is on I2C30.

[Kazi Afroza Sultana]

Hello,

As Fischer said, you can not perform a I2C reads from an ISR on nRF54L15 with zephyr. The method works offloading workthread needs to consider some latency.

You can read this previous case Source: I2C Read/Write functions in GPIO Interrupt. It's for nRF52840 but still same principal.

Thanks.

BR

Kazi

[Nick_RA]

OK, will give the work queue a go, it should be OK as I have until the end of the packet to play with time-wise after all - I guess the word "queue" put me off as it implies deferred operation.