i2c_burst_write difference nrf52 and nrf91 series

[Maaike]

Dear All,

I'm using Zephyr to configure a nrf9160 as I2C master and the OPT3002 light sensor as I2C slave.
The OPT3002 has a 16bit configuration register, which I need to write to.
For this I use i2c_burst_write(), which works fine on the nrf52 series (nrf52840 & nrf52833), with I2C_0. I can write to the register and read correct light intensity values.
However, on the nrf9160, with I2C_2, I can read the registers fine, but not write to them properly. This means I cannot get the sensor out of power down mode and therefore not read any sensor values.

Now I have seen this issue with burst_write and I should probably use another i2c write function.
However, I would like to know what the difference is between the nrf52 and nrf9160, that causes this issue to only happen on the nrf9160.

Do you have any idea what causes this difference?

Kind regards,
Maaike

[Simon]

Could you try to attach a logic analyzer to the I2C pins and see if the output differs between the nRF52 and the nRF91 when you use the i2c_burst_write function. That would be interesting to see. I'll soon take christmas vacation for some days, so I don't have time to do it myself before then.

Best regards,

Simon

[Maaike]

Hi Simon,

I will check the i2c output with the logic analyser.
Due to the Christmas holidays it might take a week (or 2) till I can get back to you with the results. 

Have a good holiday!
Kind regards,
Maaike

[Simon]

A huge part of the support team are currently on Christmas vacaction, and you may experience delayed answers. Most of the staff will be back by january 4th and you can expect an answer after then. My apologies for this.

Best regards,

Simon

[Maaike]

I was able to check it with the logic analyser and there is a difference between the nrf52 and nrf91 in writing to the configuration register. In the reading of the ID register there is no difference.

Some addresses and values:
I2C address read =  0x44
I2C address write = 0xC4
MANUFACTURER_ID register address =  0x7E
CONFIGURATION register address = 0x01
MANUFACTURER_ID = 0x5449
Configuration value to write = 0b1100011xxxx01000, where x are read only fields.
Expected configuration value to read = 0xC688  (0b1100011010001000)


Below the read ID register and the write and read to the configuration register of both the nrf91 and nrf52 are posted.

nrf91 read ID register


nrf52 read ID register


nrf91 write read configuration register


nrf52 write read configuration register

[Simon]

Sorry for the delay on this. I'm back at work and will look into this case.

Best regards,

Simon

[Simon]

Have you gotten any progress on this? Pull request 25867 may be helpful, it adds an option to concat smaller payloads.

Best regards,

Simon