How to modify the timing at TWIM write/read sequence?

[Jeffery]

Hi 

Below is from nrf9160 data sheet TWIM  section.

Using this sequence to a sensor device, we found sometimes the data read was incorrect. The sensor vendor said the root cause was the delay time

below was too short for their device to respond. Currently, it is 100us. How to enhance the time over 260us? Thanks

[Jeffery]

Sorry. I posted same waveforms 3 times.

[Einar Thorsrud]

Hi,

It seems like the sensor id doing some clocke stretching, so this time (before the snesor answers) is dictatedby the sensor, and not the nRF. If it needs a longer pause before answering, why does it not just stretch the clock longer? If this is the problem, then it seems like the sensor is behaving strangely.

Can you try to work around it by using a lower I2C frequency?

[Jeffery]

Hi Einar

Thanks. I2C frequency was the lowest(100K). The result was same.

Jeff

[Einar Thorsrud]

Hi Jeff,

I see. Did the sensor vendor say more about what caused problems for the sensor? An alternative could be to split up the sequence in several transactions and add a delay in software (with a k_sleep()) between them to ensure they are long enough, if that is indeed what casues the problem for the sensor.