Published May 21, 2017

Bikeyface Emoji Taillight (with Micro:bit)

Express yourself with your bike lights!

BeginnerFull instructions provided2 hours3,896

Things used in this project

Hardware components

BBC micro:bit board

USB-A to Micro-USB Cable

5V USB power supply (generic)

Hand tools and fabrication machines

3D Printer (generic)

Hardware 101 HW101 Marker

Story

This is the actually useful version of Bikey McBikeface! Build a rear bike light that signals turning and stopping, and displays a custom emoji the rest of the time.

The micro:bit on the front acts as a user interface. Between signals, it turns off the LEDs to save power. Push the A button to signal LEFT, B for RIGHT, and both buttons for STOP. When you do, it sends a radio signal to the back of the bike.

The module on the back (in a cute little guy housing) responds by displaying everything to the people behind you!

Both of them have 3D-printed enclosures.

Physical setup

Mount each micro:bit with a 5V rechargeable battery pack and some Velcro.

The round bar clip goes on the front, and the little guy dangles from the back. The "eye" holes double as attachment points for small zip-ties or wire.

Printing the back piece, with support material: I used glow-in-the-dark PLA, because we're baller

The front stand is modified from a holder I found on Thingiverse, reshaped to fit on a ~35mm bike bar.

Software

In order to use the radios, you currently need to program in MicroPython. Just download the Mu editor and paste in the code for each :bit, then plug in each module and hit "flash". (Only plug in one micro:bit at a time!) If your computer can't find the module, wait a few seconds and try again – or swap out your USB cable, since some of them only do power, not data.

Scroll down and copy the code below for each one.

The front bit has a bunch of extra timing stuff, in order to make the STOP sign go when both buttons are pressed simultaneously, without accidentally triggering an arrow at the start or end.

The back bit just listens for radio commands and responds with pictures. Each one displays for at least half a second. Check out the list of available "emoji" images!

Code

# Display random emotions on your bike.
# By Alex Glow; released to the public domain.

import radio
from microbit import display, Image, sleep

stop = Image("09990:"
             "90009:"
             "90009:"
             "90009:"
             "09990")
             
danger = Image("90909:"
             "90909:"
             "90909:"
             "00000:"
             "90909")
             
left = Image("00900:"
             "09000:"
             "99999:"
             "09000:"
             "00900")
             
right = Image("00900:"
             "00090:"
             "99999:"
             "00090:"
             "00900")
             
radio.on()

while True:
    incoming = radio.receive()
    if incoming == 'left':
        display.show(left)
        sleep(500)
    elif incoming == 'right':
        display.show(right)
        sleep(500)
    elif incoming == 'stop':
        display.show(stop)
        sleep(500)
    else:
        display.show(Image.HEART)

# Display random emotions on your bike.
# By Alex Glow; released to the public domain.

import radio
from microbit import display, Image, button_a, button_b, sleep

stop = Image("09990:"
             "90009:"
             "90009:"
             "90009:"
             "09990")
             
danger = Image("90909:"
             "90909:"
             "90909:"
             "00000:"
             "90909")
             
left = Image("00900:"
             "09000:"
             "99999:"
             "09000:"
             "00900")
             
right = Image("00900:"
             "00090:"
             "99999:"
             "00090:"
             "00900")

cdbutt = 0 # Countdown from pressing 1 button, so it doesn't show arrow instead of stop sign.
cdstop = 0 # Countdown after displaying stop sign, so arrows don't display.
             
radio.on()

while True:
    cdstop = cdstop + 1
    
    if button_a.is_pressed() and button_b.is_pressed():
        cdstop = 0
        radio.send('stop')
        display.show(stop)
        sleep(500)
        display.clear()
        
    elif button_a.is_pressed() and cdstop >= 150 and cdbutt >= 150:
        radio.send('left')
        display.show(left)
        sleep(500)
        cdbutt = 0
        display.clear()
    elif button_a.is_pressed() and cdstop >= 150:
        cdbutt = cdbutt + 1
        
    elif button_b.is_pressed() and cdstop >=150 and cdbutt >= 150:
        radio.send('right')
        display.show(right)
        sleep(500)
        cdbutt = 0
        display.clear()
    elif button_b.is_pressed() and cdstop >= 150:
        cdbutt = cdbutt + 1