This week, I decided to try and use an accelerometer.

First step was designing a board. I did this in kicad.

Some notes of interest:

• The ADXL343 requires 3.3V rather than 5V, so I used a regulator.
• Although actually, the datasheet recommends 2.5V, so we will see.
• One project from last year was careful to re-scale the output voltage back to 5V using transitor shields. Neil's example did not do this, though, so I am guessing it will be fine not to as well. 3.3V should be high enough to trigger a digital HIGH for the attiny44 to read.
• I added a power indicator LED and a display LED driven by the attiny for debugging.
• Smoothing capacitor between VCC and ground to reduce noise.
• Needed a 0 ohm reistor to bridge one final trace. Tried of avoid, but failed.
• Made the pads for the ADXL343 0.4mm each rather than 0.6mm, to make milling possible with the 1/64 inch bit. We will see how that goes.