Bar100 doesnt work with level shifter

Blue Robotics Products
#1

Hi.

When connecting the bar100 to the bluerobotics level shifter, I dont get any readings except for 150 deg C.

#2

Hi @uchiha,

There’s not enough information here to know whether it’s most likely to be a hardware or software issue, so a few questions:

  1. What are you trying to connect the Bar100 to
    • e.g. Arduino, Raspberry Pi, Pixhawk, Navigator, microcontroller, etc
  2. What code are you using to communicate with it?
    • and are you using one of our libraries?
  1. Does that mean you’ve connected it to something else without the level shifter and were getting different (normal) values?
    • or are you just mentioning that you’re using our level shifter as part of your setup?
#3

I am using an arduino with the bar100 example code. It works fine when connecting directly to arduino, but does not work when using the level shifter

#4

I wouldn’t recommend doing that because

  1. operating communication lines above the supply voltage of the sensor may cause premature failures unless the pins have been designed to withstand that
    • if you want you can try contacting Keller to ask if their LD series sensors have 5V tolerant I2C pins, since voltage limits are not provided in the sensor datasheet
  2. Mixing 3.3V and 5V I2C communications may result in communication errors
    • the 5V side may not properly detect “HIGH” signals from the 3.3V side, or
    • the 3.3V side may not properly detect “LOW” signals from the 5V side (if it can’t pull down low enough)
    • as is the Keller LD communication document (linked in the Bar100 Technical Details) already specifies that the sensor has tighter logic level tolerances than the I2C specification

It’s possible that using the Bar100 with 5V I2C from the Arduino may have already damaged the pins - if possible I would recommend testing it with a 3.3V device like a Raspberry Pi or Pixhawk to see if it works normally there. If that works without issues then there’s probably an issue with your level converter, in which case I recommend you contact support@bluerobotics.com to sort out a replacement / refund as relevant.