MS5837-30Bar Flight Controller I2C conflict?

Blue Robotics Products Sensors
1

Hello we are using a MS5837-30Bar sensor on our own breakout board and we are trying to connect it to the I2C-6 ports on the Blue Robotics flight controller but it never shows up in either readings in the cockpit or under vehicle setup.

Doing i2cdetect -l, it doesn’t show up in i2c-6

{F92C7227-0784-4859-9717-F053223121D4}
{F92C7227-0784-4859-9717-F053223121D4}791×180 14.7 KB

but if I use i2cdetect -y 6with and without the sensor plugged in, it clearly shows up at i2c-6 at its correct address (top: without, bottom: with)

{12B7FE5A-6EA6-4736-8C20-9E4B1971465B}
{12B7FE5A-6EA6-4736-8C20-9E4B1971465B}534×491 12.6 KB

So it is actually there and we can probably communicate with it, but I thought the MS5837-30B was suppose to have drivers already installed and could just show up on its own.

Is this normal? Is there an easy fix for this?

(Sensor works perfectly with an Arduino when testing)

2

Hi @BerkY -

Sorry for the issue! I would guess the issue is related to your “own breakout board” - does this mean you’ve developed your own PCB rather than use the Bar30? How long are your I2C wires, and do you have pull-up resistors installed?

It’s a bit confusing that the sensor would show up in your i2cdetect -y 6 without it plugged in!

I assume you’re using a Pi4 running the latest stable BlueOS 1.4.2?

3

Yes we have a pi4 with the latest BlueOS version.

We made our own board to fit our submarines hull with pull-up resistors on SCL and SDA. We have tested the board before with the blueOS MS5837 Arduino Library on our UNO and we seem to get correct results with no issues.

Furthermore the sensor seems to not respond to I2C requests made with:

  • NodeRed I2C-Out Node
  • i2cset command in the terminal
  • blue robotics python ms5837 library and a python script

In all cases we use i2c-6 with address 0x76 and in all cases we get an I/O Error. From what we have searched this could usually indicate a faulty connection. We have double checked our connections between I2C-6 port on the flight controller and the pins and have confirmed they have continuity all the way through which makes us doubt this.

We may try to solder up another 4pin connector to see if it can solve the issue. I guess we are looking to see if there could be any other explanation to what’s happening as it seems weird to have a signal integrity issue yet show up in i2cdetect.

4

Hi @BerkY
Accessing the sensor manually should not be required!

If you go to the vehicle setup page, do you see an entry for both the barometer on the Navigator, as well as the MS5837?

image
image1920×1273 115 KB

This sensor should be plug and play, unless the wires on your setup are long enough to cause communication issues. To confirm, your cable connects all the 4 connections from the I2C port and is less than 1’ long?