Yavia board supported level shifters for UART and I2C


we have a Yavia board with a Verdin iMX8MP Q 4GB Soc and we try to connect the UART and the I2C (TTL 1.8V) to an raspberry pi UART and I2C (TTL 3.3V).

So we bought a level shifter “TXB0104 4-Bit Bidirectional Voltage-Level Translator” (https://www.ti.com/lit/ds/symlink/txb0104.pdf?ts=1701928414157&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTXB0104).

Which does not work at all!

If we do a UART loopback, as descrbed in one of your How-Tos

Without the level shifter it works, but with it looks like :

So the question is could you recommend us some bidirection voltage shifters which will work with the Yavia boards UART and I2C ?

Preferably it should be a break out component which can be soldered into the UART connection.
Can you recommend something? Or does anyone can recommend a working component?


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I have a similar issue with the SOM on a Dahlia carrier board. The UARTs 1 and 2 use 1.8v ttl and I need them at 3.3. I am also using a level shifter to match the logic levels, but it’s not working. After wiring up the UARTs from the expansion headers, i cant read any data from verdin-uart1 or 2. The attached UART devices are running fine, just not ability to communicate from the Dahlia.

Hi @dan !

Welcome to Toradex Community! :partying_face:

Please feel free to browse around! :smiley:

Could you please share the schematics of how you connected the UART and I2C lines of Verdin iMX8MP to the level shifter and to the Raspberry Pi? Please also share the VCC and GND connections.

Also, are you using a breadboard for your tests? This can be problematic with high baud rates.

And which baud rate are you using for each interface?

@Glitch , I am focusing on @dan’s issue now since he created the thread. Hopefully, you will find the solution for your case in this discussion. If not, please create a new topic so we can help you with your specific case, ok? Thanks for the comprehension :slight_smile:

Best regards,

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Hi the problem was that for the “TXB0104 4-Bit Bidirectional Voltage-Level Translator” the OE pin has to be connected to the same voltage as the Vcc.

But I2C did not work with TXB0104!
For I2C we bought the adafruit 4-channel i2c safe bi-direction logic level Converter, which works for I2C

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Hi @dan !

Thanks for the update.

If this topic is solved, please mark the most suitable message as the solution. :slight_smile:

If this isn’t solved, please let us know how we can further help you.


Best regards,