- Fused
- Protected digital outputs.
- IO was 3.3V
- Rugged USB.
I didn't want the Arduino to consume all the power if there was a short.
Protected Digital Outputs
If an output was directly connected to ground I didn't want that pin to be shorted out and fail.
IO 3.3V
Everything is 3.3V now. Sensors, serial ports, Bluetooth is all 3.3V. I didn't want to have to put level translators everywhere.
Rugged USB
I needed a through-hole well-supported USB connector for repeated plugging and unplugging.
Sparkfun produces the Pro Micro in a 3V/8MHz variant, but its small form factor did not allow any fusing or other protections.
So I made my own based on firmware provided by Sparkfun for the Pro Micro 3V/8MHz.
Highlights:
- Fused to 750mA
- Dx IO protected by 100-ohm resistor
- 3.3V operation
- All IO fully broken-out
- Programming Header
- Through-hole USB B full size
- All components on Top side and had solderable
- All the standard IO broken out to Dual Female Header for two connections per pin
- 5cm x 5cm board (dirtypcb.com compatible) two-layers only
I left off the Reference Designators for the part because of the end-user. There aren't many different components so building it isn't too difficult.
To program the bootloader, use my previous post Program Raw Atmeg32u4 to Sparkfun Pro Micro 3V/8MHz Bootloader
To program with Arduino IDE use Sparkfun Pro Micro 3V/8MHZ Installing the Arduino Addon.
I have extra PCBs that were made but not used. Contact me through the Contact page
