The SoC nrf5340 I2C channel random failure with Zephyr

[Vivek]

We are using a few sensors like (IMU, Barometer ) on one of the I2C lines. All the other sensors gets detected but the IMU and Barometer does not get detected even when the CS and SDA SCL are high. The Pull up resistors (internal) does not make the SDA and SCL high and there is no 3V detected on these. However on turning the pins 43 and 45 High, the SCL and SDA becomes high and the IMU and barometer get detected.

But as the Bluetooth stack is put and activated, the detection again stops. It is arbitrary behaviour of I2C bus that is confusing us. 

Any idea what is happening here?

Schematic-4-5.pdfSchematicSLIM.pdf

[helsing]

Hi Vivek,

However on turning the pins 43 and 45 High, the SCL and SDA becomes high and the IMU and barometer get detected.

How do you specify the pins? Would you be able to share the board files, or at least the .dtsi and .dts files?

[Vivek]

We are using P1.00 and P1.01 for the I2C SCL and SDA for the IMU

the RGB (part D2) is connected to 43,44 and 45 (P1.11, P1.12, P1.13) pins as seen on page two of the pdf attached.

[Vivek]

zephyr.zip

dts file

[Vivek]

Hi,

We put a small code to detect the sensors only and all sensors are getting detected.

However on putting the entire code and activating the BLE, one line (of IMU) stops getting detected.

Can power consumption be an issue?

We have use TPS63901 that has 400ma limit. Can that be an issue.

The issue of pins 43 and 45 is no more there. 

[helsing]

Thank you for the file. I will check it out and get back to you.

[Vivek]

Okay, pl see our last comments too.

[helsing]

Vivek said:

However on putting the entire code and activating the BLE, one line (of IMU) stops getting detected.

Could you please explain this in more detail? What does it mean that one line of (of IMU) stops getting detected?

Has the layout of the device been reviewed? Is this line anywhere near the RF path?

Vivek said:

Can power consumption be an issue?

We have use TPS63901 that has 400ma limit. Can that be an issue.

What does the power budget for the devices look like? I believe this 400mA should be sufficient. We can have a closer look at this if we are not able to find something else.

[Vivek]

Hi, 

We have send the schematics to your personal account. The I2C line where the IMU and Baro are connected are not getting detected. We are sending the circuitry too. The RF is not near this line.

[Vivek]

The continuity is good and the components are well placed and connected. This is the connection from nrf5340 to LSM6DSOX

[Vivek]

Making the P1.00 and P1.01 high using internal resistors does not makes them high.

[helsing]

Hi Vivek, sorry for the delay.

From Zephyr.dts that you provided it looks like uart0 and i2c1 are both using P0.13.

Is uart0 in use when Bluetooth is used, perhaps for logging? Try changing the rts-pin of uart0 to something else and see if it helps.