Convert SS Micro 32u4 from 5V to 3.3V

For anyone interested I have hacked an SS Micro board so the MCU is running at 3.3V instead of 5V.
The hack involves cutting 3 tracks and soldering 2 wires. From the below images cut the tracks at the red lines and solder wires at the green lines.
The 32u4 datasheet says that 3.3V is to low to use 16MHz F_CPU but it appears to be working okay and if your to concerned then maybe you can re-flash the fuses to use 8MHz.
Another hack I might perform later is to replace the AMS1117-33 with the AP7361-33ER as it's pin compatible but has a lot lower Quiescent Current.
SS 32u4 Top.jpg

The reason for doing this is so I could connect a 3.3V micro SD card module to create a small & cheap USB rubber ducky.
The SS Micro is like the one here and the micro SD module like this.

That's interesting to see, but is there a reason you didn't just buy an all-in-one like this?

BJHenry:
That's interesting to see, but is there a reason you didn't just buy an all-in-one like this?

No particular reasons other than I already had the bits and I never new you could buy a cheap pre-made device. :-\

So Riva, are you developing the code for the Rubber ducky or did you found something ready made?

Riva:
No particular reasons other than I already had the bits and I never new you could buy a cheap pre-made device. :-\

Fair enough, I think that's very much in the spirit of the Arduino world :slight_smile:

Watcher:
So Riva, are you developing the code for the Rubber ducky or did you found something ready made?

I used this as a starting point to write my own code. Instead of using DIP switches I monitor the CAPSLOCK, SCROLLLOCK & NUMLOCK state and launch one of three scripts based on the key pressed.