Project tutorial
Bluetooth-Enabled Bicycle Turn Signal

Bluetooth-Enabled Bicycle Turn Signal © MIT

Are you tired of sticking your arms out to indicate which direction you're turning?

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Components and supplies

Ard nano
Arduino Nano R3
Or an ATMEGA328P on a PCB
×2
61pby065esl  sx679  tnr8syww5d
HC-05 Bluetooth Module
×2
8x8 LED Matrix with MAX7219 driver
×2
Lithium-ion power bank (or battery with 134N3P chip)
×2
Waterproof enclosure/case
×1
Toggle switch (ON-OFF-ON SPDT)
on-off-on for turn signal and on-off for power switches
×1
Adafruit industries ada592 image 75px
USB-A to Micro-USB Cable
Any USB-A cable with a 5V and ground wire will do
×2
Dupont connector and some wires
×1
12002 04
Breadboard (generic)
Or PCB for slimmer enclosures
×1
Qi wireless receiver
×1
Mfr 25fbf52 221r sml
Resistor 221 ohm
pulldown resistor
×1

Necessary tools and machines

09507 01
Soldering iron (generic)
Drill
Hy gluegun
Hot glue gun (generic)

About this project

Motivation

After commuting to work every day on my bicycle, I decided that I needed a better way to signal my turns. Sticking my arms out can be dangerous, especially if you're riding downhill in the rain (as is common in Vancouver).

I had recently got an Arduino and wanted to embark on my first project, so I decided to kill two birds with one stone!

I wanted something waterproof that I can use in the rain, and something detachable so it wouldn't get stolen, it needed to be detachable/wireless.

The plan was to have a couple of switches embedded into the handlebars (for power and for turn signal), use a Bluetooth transmitter (HC-05) for communication, and have an Arduino Nano to control it all with an 18650 lithium-ion battery (controlled with a 134N3P chip) for power. On the other end of the bike, there are two 8x8 LED matrices controlled by MAX7219 controllers, a Bluetooth receiver (HC-05), an ATMEGA328P chip to control all the components and an 18650 (or 14500) lithium-ion battery for power. I also added a Qi wireless charging receiver to charge the battery without opening the lights enclosure.

Action shots

Here's a video!

Video of the setup in action

A closeup of the case with all the gubbins:

If you don't like my boring arrows, make any indicator animation you want using my 8x8 LED byte generator found on my Github:

LED_byte_matrix_generator

Wiring diagrams

Diagram for handlebar/controller:

Diagram for the lights:

Setup instructions:

  • Set up the HC-05 Bluetooth modules to pair with each other using a master-slave setup (instructions).
  • Other Bluetooth modules with similar functionality can be used.
  • Upload code for the lights and the handlebars to the Arduino Nano (or any other ATMEGA328P based chip).
  • Wire everything up according to the wiring diagrams.
  • if using a reed switch to control power to the lights, you'll need a magnet.

Variations/upgrade ideas:

  • Reed switch to control power to the lights. If your case is too slim for a toggle switch (like my latest iteration) or you're worried about the waterproof-ness of the case, a reed switch could be used.
  • A magnet attached to the light mount can turn the lights on and the lights can be turned off by taking the lights off the mount.
  • Or a second magnet can be used to change the flux path and open the reed switch like so:
  • Neopixel rings and jewels as a turn signal, like a car with the outer ring in red and the inner jewel lit up amber and flashing when turning.
  • Add an accelerometer to detect slowing down and display a slowing down animation or flash amber lights.

Pictures of the build:

Internals leaking out:

Note: Bluetooth module, Arduino Nano and PCB separated from battery by a long ~1m cable

Testing lights before gluing everything and closing the case:

It's working! Time to mount it to my bike:

Message me for more details if you want to make one for yourself.

Thanks for reading!

Old (thick) setup pics:

Code

Schematics

Comments

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