Howto reset I2C controller for 52840

[Henrik Avenberg]

Hi,

Working on a product with a couple to sensors with i2c communication. Are normally able read values from the sensors, but sometimes the i2c bus seem to be down. No more read/write operation succeeds.

We are using a pre-production version of the Nordic 52840. Are there any known issues regarding i2c for the pre-production devices?

How do I reset the i2c controller to see if this is the reason for hanging the i2c bus?

Thanks,

   Henrik

[Kenneth]

It might help to have a logic analyzer available, so you may see when and if serial transfer stops. But to answer your question. You likely need to uninit() the driver, and then power cycle the peripheral, and then init(() the driver again. To power cycle the peripheral, write 0 followed by 1 to the POWER register (address 0xFFC) of the peripheral instance that you want to  power cycle like this:

• If TWIM0:

   
  *(volatile uint32_t *)0x40003FFC = 0;
  *(volatile uint32_t *)0x40003FFC;
  *(volatile uint32_t *)0x40003FFC = 1;
  

• If TWIM1:

   
  *(volatile uint32_t *)0x40004FFC = 0;
  *(volatile uint32_t *)0x40004FFC;
  *(volatile uint32_t *)0x40004FFC = 1;

[Henrik Avenberg]

Thanks for the reply. Just a follow up question. 

I assume that the peripheral mentioned  above is the I2C controller, is that correct?

What does TWIM0 and TWIM1 mean? Tried to google it, but didn't find anything that I understood.

Thanks

[Kenneth]

I believe I2C is trademark of Philips, so many refer to the interface as two wire interface (twi) or i2c compatible. TWI0 and TWI1 means in this case there are two hardware blocks internally that can run twi at the same time.

Best regards,
Kenneth

[Henrik Avenberg]

We have now been able to catch a log of the signal issue. Please see image below.

Using the code above does not seem to help. Do we need to insert any delay/sleep between the code lines above when resetting I2C?

[Henrik Avenberg]

[Kenneth]

It looks like some of the levels here are undefined/floating, do you have pull up on the twi lines? For instance 10k pull up on both clock and data line.