Connect-Me UART levels

I’m having some dificulties in making communicate my Connect-ME with a DS2480 (1-wire interface) through the UART. I wonder whether it has something to do with the RX/TX levels of every device.

In theory, the DS2480 TXD pin range voltage is
from 2.7 to 5.5V for high level
from 0 to 0.8 for low level
Everything seems OK at this point.

On the oher hand, the Connect-ME specs say that every GPIO pin must not exceed a little more than 3.3V, while the DS2480 RXD pin is at 4.9 V in its iddle state.

Should I use a conversion stage between UARTS?

Thanks in advance,


Hello Daniel,

Digi has a 1-wire Demonstration available on-line along with a good amount of documentation. Here is the link to that.

It may have the information you are looking for, including details on converting from 1-wire to RS232 or to the low voltage TTL the Connect ME uses.


Hi EuroTech.

The 1-wire application showed by Digi uses a commercial 1-Wire-RS232 adapter. So, there is no direct 1-Wire-TTL conversion at any point.

In another post I’ve read that the Connect-MEs with part number 50000878-XX accept 5V levels on the GPIO pins and UART lines. Thus, it should work properly.



Be carefull interfacing any 5-volt devices direct to the Connect ME. Digi does not support that, regardless of the part number. Attached is a clamping circuit.



EuroTech, your schematic seems to be incorrect. Both diodes should be inverted.


This post speaks about the 50000878-XX modules and its 5V tolerance:,1247#4765

Will look into that.