Custom 52832 board, NRF Connect 2.4.0 - TWIM doesn't work (TWI - does)

RE: Custom 52832 board, NRF Connect 2.4.0 - TWIM doesn't work (TWI - does)

Paskin — Wed, 26 Jul 2023 16:07:28 GMT

Thanks a lot for the solution!

It is a good idea to mention this point in I2C part of the documentation. In general - it is quite hard to find a good samples for working with interfaces and sensors on top of device trees. As well as DevZone articles - many of them explaining the behaviour of legacy SDKs and sometimes not applicable to a recent ones.

RE: Custom 52832 board, NRF Connect 2.4.0 - TWIM doesn't work (TWI - does)

Jørgen Holmefjord — Wed, 26 Jul 2023 14:40:52 GMT

Both the TWI and the TWIM driver in Zephyr is set to skip GPIO configuration in the nrfx drivers. In order for TWI/TWIM to work properly, you need to enable pullup on the pins. This can be done using internal pull resistors, by setting bias-pull-up property in the pinctrl devicetree. This is not set by default for the i2c nodes in nrf52dk_nrf52832 target, as the board will handle this automatically. This is likely the problem in your case, please try to add the bias-pull-up property to your overlay.

RE: Custom 52832 board, NRF Connect 2.4.0 - TWIM doesn't work (TWI - does)

Paskin — Wed, 26 Jul 2023 14:06:28 GMT

Yes, it reproduces on at least one different (also custom) board.

But I did some mixing and matching and found that channel one, where both SCL and SDA lines are pulled up via 10 k resistors - works in both modes, and channel zero w/o external pull-ups - doesn't. Could it be the cause - say, TWI engages an internal pull-ups and TWIM has to be "told" to?

In your tests - were the lines pulled up?

Thanks,

RE: Custom 52832 board, NRF Connect 2.4.0 - TWIM doesn't work (TWI - does)

Jørgen Holmefjord — Tue, 25 Jul 2023 13:25:00 GMT

Hi,

Do you see the same issue if you add the devicetree changes to an overlay for a different board (e.g. nrf52dk_nrf52832 target)?

Can you post your exact sample with the custom board files, along with screenshots of the steps used to reproduce the issue? I tried to add similar overlay to the nRF52 DK, but I'm not able to reproduce the issue you are describing:

Best regards,
Jørgen