enter image description hereI try to connect a Sensirion SPS30 Particle Sensor to my Raspberry Pi 3B via I2C. There are other sensors on the I2C Bus - and they work without any problems, but I fail to detect the SPS30.

What I have tried:

  • The SPS30 is connected to 5V, Pins 4 & 5 are connected to GND
  • I use a splitter (3K/2K) to connect SDA/SCL, and the I2C lines are all pulled-up to 3V (it doesn't work without any pull-up/pull down resistors, I think I tried many possible combinations)
  • I've set the baudrate to 100,000 (dtparam=i2c_arm=on,i2c_arm_baudrate=100000)

None of this seems to work.

Does anyone have any suggestions what else to try?

uname -a
Linux raspberrypi 5.10.17-v7+ #1403 SMP Mon Feb 22 11:29:51 GMT 2021 armv7l GNU/Linux
  • Clear photos showing the connections may help.
    – joan
    Apr 19, 2021 at 12:23
  • I've added the circuit - thanks!
    – Gux
    Apr 19, 2021 at 13:01

1 Answer 1


It is unclear what you are trying to do but this is certainly not the way to do it.

The Pi has pull-ups on I²C lines so none are needed.

The series resistors will effectively prevent anything from working; I²C uses open drain circuitry.

Most I²C devices will work at 3.3V if there are no pullups to 5V, occasional devices need higher voltages and require a level converter.

See rPi3 I2C-LCD, do i need a logic level converter?

  • The resistors are to get from 5V to 3.3V on SDA/SCL - I've noticed that the pull-up resistors don't do anything. Bu even when I connect the SPS30 directly to SDA/SCL I can't detect it (e.g. with i2cdetect)
    – Gux
    Apr 19, 2021 at 13:24
  • You obviously don't understand how the circuit works and the bus is bi-directional. You need NO pull-ups on the devices BUT if they have pull-ups you need a level converter.
    – Milliways
    Apr 19, 2021 at 13:28
  • Thanks - this explains a lot! I'm sorry, this is my first excursion into this type of electronics, I used to stay away from hardware if possible.
    – Gux
    Apr 19, 2021 at 13:35
  • I have added a Level Converter - but still without success unfortunately. It is connected to 5V on HV and 3.3 V on LV - and SDA and SCL are both passed through.
    – Gux
    Apr 20, 2021 at 15:23

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