using pyupdi and serial Tx/Rx

[paulskirk53]

Hi, looking at the connection circuit for pyupdi, is it possible to have the resistor connected across the Tx and Rx pins and still use those pins for serial data transmission over an AVR 4809 USART? The reason I'm asking is that if it's possible to do that, I can introduce a switch into the line that feeds the UPDI pin on the 4809. With the switch in the open position the UPDI line will be disconnected and serial comms over the USART would work as normal, when the switch is closed the UPDI line is connected and the chip can be programmed?
Just trying to have the best of both worlds from the FTDI I use for programming the 4809.
Or would it on reflection work like this:
https://docs.google.com/document/d/1ZoT3vDgNXXhkSActH86etUCHfQCsM4SLs3Brdldb27c/edit?usp=sharing

Thanks for thoughts on this.
Paul

[mraardvark]

The resistor is really to handle contention - since UPDI is bidirectional while TX and RX are dedicated lines...