i2c BMP sensor

[bvandijk]

Hi All,
I'm new to this forum, my name is Bas, I have a sailboat in the Netherlands and have been using OpenCPN for a couple of years.
Currently trying to upgrade to Pi4 and adding some sensors.

I have Openplotter installed (the default stable release from the website) on a Pi4.
I want to read a BMP sensor using the Signal K server but I can't get it to work:

• i2c is enabled in pi settings
  
• i2c module from Openplotter is installed
  
• I have an IMU sensor that I got to work with Pypilot, it shows up in Signal K and I can plot the compass reading in the Tommy/KIP.
  
• I have an Adafruit demo program to readout the sensor using Python which works, which tells me the sensor is ok and the wiring is correct.
  
• When I add the sensor in i2c the address shows up, I then add it and give a label name for temperature (which is somehow missing but I've read this is normal).
  
• I then enable the connection in Signal K.
  
• If I then open the signal K server I see the i2c in the connection part of the dashboad but there is no activity. 
  
  
• Also the labels do not show up in the data browser.
  

Anybody knows what I'm forgetting/doing wrong?

Many thanks, Bas

[bvandijk]

BTW: I found this:

https://forum.openmarine.net/showthread....ght=BMP280


and did the hack in the file but the result is still the same. Complete silence in Signal K.

[bvandijk]

Ok, I solved it. 

So for others that may have the same issue:

Apart from the above hack in the file you need to do this:

The BMx280 sensor can work on address 76 or 77. Apparently, even though the i2C module from Openplotter sees the 76 address, the library assumes the address to be 77...

To get the sensor to work on 77 you need to connect the SDO pin to 3.3V. After I did that, removed the sensor and reinstalled at 77 everything worked.

BW,
 Bas