Information

Frequently asked questions
Do you have the exact dimensions, or even better a CAD drawing of the sensor in
3D?
Sensors are 18mm x 149mm. Zipped step file is available in github repository.
How to set up multiple sensors connected to one Arduino Uno?
You can connect several sensors to a single I2C bus. Exact maximum amount depends
on many factors, mostly on the wiring length. To have several sensors working on a
bus, you have to assing an individual address to each sensor. To do that, connect each
sensor one by one and run an address change routine. Code is available as an
example of Arduino library. Raspberry Pi example is also available.
Can I use a X meter long cable without affecting the sensor measurements?
It depends. Note that I2C bus is not ment to run on cables, so it's a hack already.
Nevertheless, a lot of products do this. I suggest reading online resources about running
I2C on long cables to get some background information, but generally, to support long
cables and ensure robust communication you can do the following: * lower pullup
resistor value, calculation is a bit complicated, but it seems you can go as low as 1k.
More info here. * slow down I2C speed. Consult your controller board documentation on
how to do that * Use shielded cable
How to solder wire to the sensor?
Do not solder wires to the 6 pad connector - this is a programming header. Solder to 4
pads marked VCC, SCL, SDA, GND at the edge of the board. I suggest using a
shielded 4 wire cable designed for security signalization installations. Do not solder the
shield to the sensor, but ground it at the controller board side. Fix cable to the board
using zip tie. Cover the wire connection and SMD parts with glue-lined heatshrink. Do
not use a simple heatshrink as it will eventually let water in and will not allow it to
evaporate resulting in short sensor lifetime.
Do you offer the source code from the i2c chrip project? Can I reflash firmware of
the sensor?
Yes, sure, the sensor is open source hardware, all the code and hardware files are
available on the github page. You can use 6 pad header to program it using any AVR
programming hardware like TinyISP, UsbAsp and similar. Also, you can use
your Arduino board as an AVR ISP programmer.
Communication with ESP8266-based systems is unreliable, sensor sends data
then stops working.