CCS811 Gas sensor doesn't communicate with nRF9160

[nrgunarat]

Hi,

I am using the nRF9160 to read data from the CCS811 gas sensor, and logs data on LTE Monitor. I am using the BME280 sensor to read temperature and pressure values and both CCS811 and BME280 sensors share the same GPIO pins and use I2C to communicate. So for I can read data from the BME280 sensor, but not the CCS811 sensor.

I am using a Windows laptop and as the software version, I am using nRF Connect v3.3.0, Programmer v1.4.2, and LTE Link Monitor v1.1.1. To generate the merged.hex file, I have been using the Segger Embedded Studio V4.52 version. I am directly using the sample CCS811 code from the NCS folder to Build and Run the solution. I really appreciate it if anyone can help.

Looking forward to a reply.

Thank you,

Nilupa

[Didrik Rokhaug]

Hi.

Do you have a logic analyzer or an oscilloscope you can use to get a waveform of the communication between the nRF9160 and the CCS811?

We are aware of a compatibility issue between Zephyr's I2C driver and the nRF9160's TWIM peripheral. This issue causes a STOP/START condition between each byte sent, which will cause a different behavior in the slave than without the STOP/START condition.

This limitation is also documented in Zephyr, see the note in the i2c_transfer documentation: https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/zephyr/reference/peripherals/i2c.html#_CPPv412i2c_transferP6deviceP7i2c_msg4u8_t5u16_t

We are looking into ways to work around this limitation, but I would like to see a waveform of the communication so that we can confirm that this is the issue you are having.

Best regards,

Didrik

[nrgunarat]

Hi Didrik,

Unfortunately, I don't have a logic analyzer or an oscilloscope to produce the waveform. Is there another way to troubleshoot?

Thank you,

Nilupa

[Didrik Rokhaug]

Do you have a 52 or 52840 DK?
Both of them have TWI modules (not just TWIM). If you are able to run the "same" application on the nRF52 but using the TWI peripheral instead of TWIM.

Any LTE-related code will obviously not work, but the I2C related code should work without much modifications, if any. Just make sure that the compatible-line in the device tree says nrf-twi, not nrf-twim.

Also, I highly recommend you get an oscilloscope with digital inputs or a logic analyzer. It is almost impossible to debug these kind of issues without one.

[nrgunarat]

Hi, Yes nRF9160 board has nRF91 and nRF52 chips. how do I make sure the compatible-line in the device tree says nrf-twi, not nrf-twim?

[Didrik Rokhaug]

Sadly, that does not work, as none of the GPIOs on the nRF52 is routed to the header.

I would highly recommend that you get a logic analyzer. It makes projects using any digital bus much easier.