Problem with USB-UART on chip CP2102 (doent receive data)


I have USB-UART module on chip CP2102, connected to host PC and Rx-Tx pins connected to Jetson NX UART pins
I can send data from the host PC (I see it in minicom on the jetson), but nothing received from the jetson on the host.
I connect my oscilloscope to Tx pin on Jetson and see that Low level signal is not fully low:

I checked about three CP2102 - the same
When I short Tx-Rx on NX, its works perfectly
I bought another USB-UART (on PL2303 chip), it works fine
Has anyone seen something like this? Does CP2102 not compatible with Jetson NX?

I have one idea, but I’m not sure about this.
I think that inside NX there is a pulldown resistor that has a value close to the value of the pullup resistor in CP2102. When NX trying to set Low level, these resistors become voltage divider, and we see half the voltage (~1.6V) on the oscilloscope.
(All values in the picture are for example only and are random)

Hi, do you mean the UART2 port on NX? It looks like compatible problem caused by pin drive capability. There is a level shift on board for UART2, please check the datasheet of level shift for possible compatible problem.

I’m using UART1(on 40 pin header)
Is there a similar level shift?

Is your UART using 1.8V logic levels, or 3.3V? The Nano will probably be looking for 3.3V.

My UART is using 3.3V

The level shift of UART1 is TXB0108RGYR, you can check its datasheet.

Ok, thank you, I’ll see

See my thread here:

I think the CP2102 latches up.

Stop using it. I think my Nano may have been permanently damaged.