Piicodev transceiver & Raspberry pi 3/4/400 problem

I am a newbie.

I was trying to send from a Rpi pico and receive from a Rpi 4 and 400. I get the following error:

  • Can’t communicate with the address 0x1a - check wiring


  • Couldn’t find a device - check signals and wiring

Can anyone help me, as both the transceivers work on the Pico, but not the pi. Even trying to send from the Rpi 4/400 comes up with the errors above.

DIP switches aren’t being helpful, so that isn’t the issue.

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Usually means the I2C interface is not connected correctly.
The data and clock pins could be the wrong way around.

Does the green light on the Piicodev TX/RX light up ??
The Piicodev TX/RX guide is a good example of how to setup the Pi 4 and Piicodev TX/RX.
The easiest way to connect the Pi 4 to the transceiver is to use the Piicodev breakout board and the cables. (see Pic)



Hi @Andrew263297 - welcome to the forums.

Thanks for your input Jim, I have a couple other sanity checks to add before we have to go deeper:

  • does the transceiver power LED light up?
  • is the i2c peripheral enabled from the sudo raspi-config menu?
  • are the DIP switches in the default state: all OFF
  • does the device respond with address 0x1A when you execute the following in the terminal i2cdetect -y 1

A picture of your connections may also help if you are not using the standard connection scheme shown in @James46717’s post / the tutorial.

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The light flickers, but I still get the same message anyway

Yes the switches are off

this particular error message may be from an old version of PiicoDev_Unified.py - are you operating with the latest version? From thonny you can check the current PiicoDev library version
which ought to be v1.10.0 at the time of writing


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It is a new version

The code might be the problem

Yes, it is the same version as suggested

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There are two green lights on the board.
One indicates power and should be on all the time.
It is near the white connector.
The other indicates TX/RX state and flickers when transmitting and receiving.
It is labeled Tx/RX.

Which one is flickering ?
If the board is not recognised in the software, then the TX/RX should be off and the power LED on all the time. Also the board should be powered by the 3V3 pin on the Pi 4. If using the breakout board and the cables supplied by Core Electronics power and pin connections will be correct.

If you are just connecting to the GPIO pins, ensure you are connecting to the 3V3 pin.


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The error may be a red-herring - the device may still be transmitting.

if you have a second transceiver you can set one up to transmit and one to receive. I suspect you may have an otherwise working build, but you’re getting a spurious error due to a poorly handled exception in the driver.
Im curious to see what happens if you were to follow this example in the guide.


After a couple of queries, I get a Connection Timed out error and “PiicoDev cannot communicate with address 0x1A”. It seems to be a problem with the module library.

Does this mean it work for a few queries then stops working ?

Transmission takes time, if you send continually the device will buffer overrun. There needs to be a gap between messages.