I have been working more with 3.3 volt projects lately and wanted to make programming them with an FTDI adapter as easy as possible. Sure you can switch most FTDI adapters from 3.3 to 5 volts (the FT232RL chip has a built in 3.3 output as well as logic level selection), but it involves scratching a jumper wire and soldering pads. This isn’t bad to do once, but to go back and forth is time consuming and rough on the boards.
So, I made my own FTDI adapter with an easily changed jumper for voltage selection. I also added a power LED to let me know that it’s plugged in and ready to go, threw in some RX and TX indicator LED’s and all required caps (read the data sheet), and mini USB jack. I ordered the boards from OHSPark.com, and as always, they were great.
Eagle files are on my Github page, or you can grab just the schematic in PDF format here.
Adafruit has an FTDI Friend and Sparkfun has an FTDI Basic if your not up to soldering 28 Pin SSOP packages, or just want one. 🙂