Hi, I have just bought Bar30 sensor and I would like to use it using Arduino UNO. But then based on the suggestion by the bluerobotics, it must connect to i2c level converter which cannot be found in my country. And to buy it online, it might take longer time to arrive. Any idea on how to connect the Bar30 sensor with Arduino UNO without the i2c?
Hi,
We recommend the use of level shifting circuits to allow a safer connection between the 3.3V sensors and 5V micro-controllers.
Can you buy one locally ? Probably you’ll be able to find a store that sells level shifting boards, you can also buy the IC for that, check the PCA9306 or any other.
You could also do things that can damage your sensor or microcontroller that may work out for you, but 
we do not recommend any of the following steps :
- Put one resistor with value between 1K and 10K between SCL and 3.3V and a second one between SDA and 3.3V, this may damage your 3.3V supply but it’ll create a poor 3.3V SDA/SCL compatible signal.
Or:
- Connect a 3.3V power supply in your Arduino VIN pin, this can result in a working Arduino that has a poor 3.3V IO compatible signal. Remember, to not connect anything else that can provide 5V to the board. So the only things that should be connected are: 3.3V supply <-> Arduino <-> Bar30. Don’t forget to disconnect everything from the board before connecting the USB to flash, and don’t forget to remove the USB when connecting the 3.3V power supply and Bar30 to test.
Or:
- It’s indeed truth that you can damage BAR30 while using the I²C with 5V, but you could try if you are really willing to put the sensor on risk to do your work.
I use these regulators to drop the 5v to 3.3 volt that runs these or these level shifters.