Parker Dillmann posted an update on his OctoPROBER board an 8 channel K-type thermocouple temperature logger, we wrote about it previously:
I was having an issue with the FT230X being active while the 3.3V rails being turned off. The FT230X would backfeed voltage down the TXRX lines into the propeller which would power the 3.3V rail to ~2.7V causing the soft power switch circuit to turn on. I fixed this by running the RESET pin of the FT230X to the propeller and pulling it up to the switched 3.3V rail. The propeller can control whether the FT230X is in suspend mode or is active. Pulling RESET low will HI-Z the TXRX pins and allowing the propeller to turn off the soft power circuit completely without voltage backfeed.