Is it possible to connect a USB-FTDI to a circuit which has a 12V external power supply without damaging the FTDI component?
My thinking for the AT89, is to use the USB to FTDI to power 5V, and add 12V to the RST pin as suggested in the datasheet.
So to sum it up:
If I connect the GND of the FTDI with the GND of the External 12V, will that cause problems?
J