Automatic Bike Brake Light by ChPech

Last crawled date: 3 years, 1 month ago

This is an automatic back light for electric bicycle. I wanted it to work without switches for the brake levers so I used an accelerometer.
The software can be found here: https://github.com/ChristophPech/BrakeLight
The LEDs are powered through a Mosfet and the Arduino's PWM controls brightness for normal operation and braking state.
The accelerometer is polled at 2kHz then accumulated to 10Hz and put through a band pass filter to remove noise (low pass) and align to the normal orientation (high pass)
You can use any logic level Mosfet, the pull-down and gate resistors are not strictly necessary but without them I got some glitches with my cheap Chinese nano clone. The status LED can be omitted too but it is useful to see if it works, the on board LED cannot be used when using SPI.
Depending on you input Voltage you might want to add 5V DC converter for the Arduino because it can handle no more than 12V (my cheap Chinese clone didn't work reliably with 12V either)
Arduino Nano (or Mini or Micro)
N-Channel logic level Mosfet: (e.g. RFP30N06LE)
12V COB-Led module (e.g. Sumbulbs )
Adxl345 (Sparkfun breakout)
Red rectangular back reflectors