HELP NEEDED! TWI_Scanner not finding MS5837

[raydayrayday]

Hi All,

Im pretty new to embedded systems and currently trying to connect a TE MS5837 30B pressure sensor to a nRF52840DK (pca10056) which is all being done via Segger (SES). 

My application code is failing to see the MS5837 sensor so Im testing using the TWI_Scanner example in the Nordic SDK (nRF5_SDK_17.0.2_d674dde) but its still failing to get a response. I purchased another 4 breakout boards from ebay and the TWI_Scanner example is still failing to find any of them. I've tested the ports and jumpers on an IMU and it was successful.

Is there something Im missing here? What are the chances of 4-5 breakout boards being faulty? It should just be a standard I2C connection/communication no?

Hardware:

 - nRF52840 DK

- TE Connectvity MS5837 on a breakout board (https://www.ebay.com.au/itm/402856356136)

Software

 - TWI_Scanner example in nRF5_SDK_17.0.2_d674dde

Any help/comments will be appreciated!!

Thanks in advance,

Ray

[Kenneth]

Do you have a logic analyzer trace to monitor the TWI pins? Is the breakout board powered with common gnd/vdd as the DK? You are sure you have not mixed CLK and DATA, and that there are pull-up resistors on the TWI pins? Some sensors can be setup to use a different interface, so maybe double check that TWI is selected.

Kenneth

[raydayrayday]

Thanks for the response Kenneth! Very much appreciated, I've been scratching my head on this one for weeks. In response to your questions;

1. Is the breakout board powered with common gnd/vdd as the DK? -> The breakout board is powered by the VDD and GND on the nRF52840 DK.

2. You are sure you have not mixed CLK and DATA? -> Those are the i2c pins, and I think they are correctly connected to the defined i2c pins on the nRF52840 DK. I've tried Pins SDA 27, SCL 28, and on 29, 30, 31..... all with no response.

3. There are pull-up resistors on the TWI pins? -> That's what I'm not sure of, as I don't have the schematic of the breakout board nor can we find one on the internet.

4. Some sensors can be setup to use a different interface, so maybe double check that TWI is selected. -> This sensor is using I2C. 

I am also looking to try some pull up resistors on the I2C pins....

[raydayrayday]

We've just tried testing it with the Arduino bootloader and we get a response and readings from the MS5837 sensor however when we try with just the TWI_Scanner in the SDK, we still get no response. 

https://github.com/bluerobotics/BlueRobotics_MS5837_Library/blob/master/src/MS5837.cpp

Any ideas?

[Kenneth]

We need a logic analyzer trace to get further.

Kenneth