i2c_burst_read and i2c_burst_write not working on NRF5340

[MarkoSagadin]

Greetings!

we are using nrf5340dk to communicate with a Nucleo shield that has LIS2DW12 accelerometer on it (shield is X-nucleo-IKS01A3). We have a problem communicating with the accelerometer as we are not getting correct sensor values.

Our setup:

• We are using NRF5340dk with QKAADB revision of the chip
• We are using NCS V1.4.99
• We are using the following command to build firmware: west build -b nrf5340dk_nrf5340_cpuapp && west flash
• We are using Zephyr Sensor API to access LIS2DW12: https://docs.zephyrproject.org/latest/reference/peripherals/sensor.html

Function sensor_channel_get is always returning only zero values and we can confirm this is true by the logic analyzer scans.

After some search on the Internet we found a similar issue on the DevZone here: https://devzone.nordicsemi.com/f/nordic-q-a/54451/nrf5340-support-in-nrf-connect-sdk-and-zephyr

We managed to fix the problem by going into i2c driver files for LIS2DW12 (ncs/zephyr/drivers/sensor/lis2dw12/lis2dw12_i2c.c) and replacing i2c burst functions with normal i2c functions.

Below you can see the part of the file that we changed:

static int lis2dw12_i2c_read(struct lis2dw12_data *data, uint8_t reg_addr,
				 uint8_t *value, uint16_t len)
{
	//return i2c_burst_read(data->bus, lis2dw12_i2c_slave_addr,
			      //reg_addr, value, len);

    return i2c_write_read(data->bus, lis2dw12_i2c_slave_addr, &reg_addr, 1, value, len);
}

static int lis2dw12_i2c_write(struct lis2dw12_data *data, uint8_t reg_addr,
				  uint8_t *value, uint16_t len)
{
	//return i2c_burst_write(data->bus, lis2dw12_i2c_slave_addr,
			       //reg_addr, value, len);

    uint8_t temp_buf[1000] = {0};
    temp_buf[0] = reg_addr;
    memcpy(&temp_buf[1], data, len);

    return i2c_write(data->bus, temp_buf, len+1, lis2dw12_i2c_slave_addr);
}

With above change we can communicate with the sensor. What can be done to fix the i2c burst functions, as we obviously can not use this workaround in production?

Best regards,
Marko

[Carl Richard]

Hi, Marko!

Thanks for reaching out. Can you confirm that there is no activity at all when checking with the logic analyzer? Some sensors are not compatible with the _burst_write() from the nRF5340 as the TWI implementation generates repeated-starts between payloads. Though this should not affect _burst_read.

I will check with the developers on this!

Best regards,
Carl Richard

[MarkoSagadin]

Hi Carl!

Another questions: is there a workaround that we can make now in our own code, without making changes in Zephyr base code?

Thanks,
Marko

[Carl Richard]

Hi again, Marko!

Ok. I agree that your issue seems to originate from the nRF5340 implementation and that the _burst_write fails to properly execute in the init. As for a workaround I believe the best way would be to take the LIS2DW12 sensor driver code and integrate it in your own project and source, so that it's independent of Zephyr. 

Best regards,
Carl Richard

[MarkoSagadin]

Hi Richard,

we end up doing this, so I marked your replay as an answer.

Thanks,

Marko

[Carl Richard]

Good to hear! I was informed that there are some work being done to mitigate this, though I don't know if it works/is complete yet.
You can look into this pull request for Zephyr for more information.

Best regards,
Carl Richard