Project 2:
    Using Project 1 board with additions
    Accelerometer
    USB power, overall budget 500 mA

avrdude -c usbtiny -p t2313 -U flash:w:main.hex

Materials
new:
- Sparkfun USB Breadboard 3.3V PS, bag-of-parts:
 - LM317
- STEVAL 135A for LIS2DH
- 24-pin wide DIP socket

The STEVAL interface
Pin 1:
 SCL* I2C serial clock (SCL)
 SPC  SPI serial port clock (SPC)
Pin 2:
 SDA* I2C serial data (SDA)
 SDI  SPI serial data input (SDI)
 SDO  3-wire interface serial data output (SDO)
Pin 3:
 SDO* SPI serial data output (SDO)
 SA0  I2C less significant bit of the device address (SA0)
Pin 4:
 CS*