nrf52832 use specific pin assignment can cause twi function not working

[Cooper]

Hi

I found a strange issue on nrf52832. And I use nRF5-SDK-v13.1.0.

When I assignment P0.7->SCL & P0.6->SDA, the twi function not working. But I change the assignment to P0.6->SCL & P0.7->SDA, it works fine.

There has a same issue on the other post. https://devzone.nordicsemi.com/question/131232/twi-scl-and-sda-pins-7-and-6-not-working-on-nrf52/

And I also try P0.8->SCL & P0.6->SDA, the twi function not working too.

Is it a nrf52832 design defect?

If can, somebody can check this setting to help me confirm the issue?

[endnode]

TWI aka I2C doesn't work out of the box, it needs external pull-ups. Sometimes you can avoid them and it works, sometimes not. Now if you are using nRF52 DK then on certain PINs you might have some external components and then some types of wired protocols may or may not work. What board are you using? What I2C speed you want to achieve? Is nRF52 Master or Slave? What device is on the other side of the wires?

[Cooper]

But I have already use external pull-ups. And I use 3rd party nrf52832 module & pca10040 to test the config, the result is same. And my nRF52 is master, and the slave sensor is ROHM bm1383glv.

[endnode]

That sounds strange, I've never had problems with wiring SPI or TWI on any nRF5x pin allowed. Do you have some logical analyzer trace or at least oscilloscope to see what are real values on these PINs when it works and when it doesn't?

[Cooper]

After I check the program initial procedure. I found P0.6 is assigned to UART TX in the "log_init()". And "log_init()" is before my twi initial procedure.

And I delete the "log_init()", and the twi work normal.

This is my fault. I forgot comment "log_init()".

[endnode]

Does the video show failing case? Are these glitches when SCL goes LOW the cause on receiver side or are these valid clock-stratching situations to hold incoming data? Other than that you can still have problem with digital values and shape of LOW-HIGH slope of your signals, they seems to have some delay to reach 3V3 (or whatever is HIGH limit) and that can cause problems on receiver's side...