RE: Software I2C / switching I2C pins while runtime

Michal — Fri, 29 Jul 2022 14:33:44 GMT

Hello Jonas,

Thank you for the information. I will mark the ticket as closed then.
In case of any other questions, please open a new ticket.

Best regards,

Michal

RE: Software I2C / switching I2C pins while runtime

JonasGel — Tue, 19 Jul 2022 13:13:01 GMT

Thanks Michal,

I have tested dynamic pincontrol in SDK 2.0 but struggled a little with the implementation.
And because it actually only should be used during startup, I watched out for an alternative.
I Implemented it now successfully with the gpio-i2c driver and will later measure current consumption of this implementation against the hardware i2c-interface.

(gpio-i2c driver: https://github.com/zephyrproject-rtos/zephyr/issues/27855 )

Best Regards, Jonas

RE: Software I2C / switching I2C pins while runtime

Michal — Tue, 12 Jul 2022 08:38:40 GMT

Hello Jonas,

The absolute easiest way would to be to put both sensors on one I2C bus. Even if it the exact same type of sensor, there is often a way to change the address by pulling a pin to either supply voltage or ground.

If it is still not possible, then yes, it is possible to switch the I2C pins during runtime or use a software/bit-banging I2C implementation.

I am going to assume that you are using NCS 2.0.0 and the new default Pin Control (pinctrl) API.
Please remember to always state the version of NCS you are using so that we know which features are available to you.

For hardware implementation you would have to use Dynamic Pin Control. Just remember to suspend the I2C peripheral before switching the pins.

I would highly recommend reading the pinctrl documentation
https://developer.nordicsemi.com/nRF_Connect_SDK/doc/2.0.0/nrf/ug_pinctrl.html

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/2.0.0/zephyr/hardware/pinctrl/index.html

The second link includes a section about dynamic pin control:
https://developer.nordicsemi.com/nRF_Connect_SDK/doc/2.0.0/zephyr/hardware/pinctrl/index.html#dynamic-pin-control

A sample utilizing dynamic control:

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/2.0.0/zephyr/samples/boards/nrf/dynamic_pinctrl/README.html

As for a software I2C, there was a driver in nRF5 SDK (components\drivers_nrf\twi_master\deprecated\twi_sw_master.c), but I don't think we have any in NCS, so you would have to implement your own.

Hope that answers your question.

Best regards,

Michal