Change I2C direction of SDP3x Airspeed Sensor it (SDP33)

Hello to everyone,

according to the datasheet of the SDP3x sensor provided by Sensirion, three different I2C addresses can be configured for the sensor of the SDP3x Airspeed Sensor kit. We’ve tried to do so, however we weren’t able to change it. How can the sensor be accessed in order to change the I2C address? If it is neccesary to open it up, how do you do that?

Thank you in advanced.

You can change the I2C address in changing the resistor you can see in the picture (blue circle). Check the datasheet please.

Thank you very much

I tried this instruction, but I am having problems with it.

I tried change i2c address by changing the resistor shown in picture. For first sensor, I used 1,2KOhm resistor, but FC didnt see it connected to i2c bus, so I shorted address select and gnd pads with solder. Sensor went back to default address and is working normally.

On second sensor I soldered 1,2KOhm resistor between address pin and gnd pad of resistor next to bottom of the board. FC could not see it on i2c bus at all. When I bypassed resistor with piece of wire, sensor went back to default address. Next I changed resistor to 2,7KOhm to test another address. Again, FC could not see device at all.

If address pin has short to ground or left unconnected, its default address. With resistor values from datasheet, sensor is not appearing on i2c bus.

FC is Holybro Durandal & PX4. FC is rebooted between each try.
Resistors are within 2% tolerance. According datasheet, this should be ok.

Any ideas?

changing address actually worked, Arduino Nano reads sensor with resistor just fine. Problem seems to be somewhere in PX4 SDP3x driver.

Can you try to set I2C frequency at 100khz ?

@ESPrtk_ESP32_RTK yes, the frequency is set to 100kHz.
The problem was that sdp3x sensors that has not-default address are not recognized (and not seen at all) automatically by PX4 so the driver is needed to be started with correct bus and address option, but it works fine after that, logging data from the sensors.

Because I suspect the I2C frequency is too high which will cause the I2C scanner to fail. But it looks like you’ve got a way to fix the problem, Congratulations !.