Arduino Pro Micro
The Pro Micro is an Arduino-compatible microcontroller board developed under an open hardware license by Sparkfun. Clones of the Pro Micro are often used as a lower-cost alternative to a Teensy 2.0 as a basis for a DIY keyboard controller/converter when a lower number of pins would suffice.
Like the Teensy 2.0, it sports an AVR ATmega32u4 8-bit microcontroller which has an integrated USB controller. It has a micro-USB type B port (Teensy 2.0: mini-USB), 18 I/O pins (Teensy 2.0: 25 I/O pins) and an integrated voltage regulator for 3V operation.
The Pro Micro is sold in a 3.3 V version (8 MHz) and a 5 V version (16 MHz).
On the 3.3 V version, shorting a solder bridge (J1) on the chip bypasses the 3.3 V voltage regulator on the board. This would allow 5 V operation and running at 16 MHz clock. At 3.3 V, the ATmega32u4 is otherwise limited to 8 MHz clock.
The ProMicro has three LEDs:
| Colour | Function |
|---|---|
| red | power on |
| yellow | USB receiving data |
| green | USB sending data |
Pinout
| Arduino | AVR | ↑ | AVR | Arduino | ||
|---|---|---|---|---|---|---|
| USB port | ||||||
 |
||||||
| TX | D1 | PD3 | RAW (+5V from USB) | |||
| RX | D0 | PD2 | GND | |||
| GND | Reset | |||||
| GND | Vcc (+3V*) | |||||
| SDA | D2 | PD1 | PF4 | D21 | A3 | |
| SCL | D3 | PD0 | PF5 | D20 | A2 | |
| A6 | D4 | PD4 | PF6 | D19 | A1 | |
| D5 | PC6 | PF7 | D18 | A0 | ||
| A7 | D6 | PD7 | PB1 | D5 | SCLK | |
| D7 | PE6 | PB3 | D14 | MISO | ||
| A8 | D8 | PB4 | PB2 | D16 | MOSI | |
| A9 | D9 | PB5 | PB6 | D10 | A10 | |
The pinout is nearly identical to the Arduino Pro Mini which has pin 3 as an additional Reset line instead of Ground.
Programming
Uploading native software to run on the Pro Micro works different than for the Teensy 2.0. There is no reset button on the board, instead two pins have to be shortcut twice to bring the device in bootloader mode for 8 seconds. While the Teensy comes with an graphical uploader tool, the Micro Pro is programmed using a command line tool called avrdude. Sparkfun's and scottc's tutorials explain this further (see links).
See also
- Deskthority forum tutorial: How to use a Pro Micro as a cheap controller/converter by scottc
- ProMicro Product Page, with links to schematic, EAGLE files, datasheets, drivers and an application tutorial
- Teensy
