FAIL: RGB LED Indicators for a Cycling Jacket

My new job involves me driving into Lancaster City Centre. After a trial run on my induction day I figured it would be easier and quicker to cycle part of the way. So what do I need? An RGB LED indicator grid to go on the back of my cycling jacket of course!

This project is NOT finished. In fact – it’s not even started! But there has been a lot of lessons learnt which I want to share.

The general plan was a grid of lights on my back that would show a left arrow when I pressed a button on my handlebars and a right arrow when I pressed a different button. I also wanted a always on display for visibility – like a smiley face!

jacket_grid

The minimum amount of lights I would need for this pattern overlapping is 15. The colours above are just for demo. The lights would actually be one colour. I didn’t want a disco distracting drivers behind me!

Plan A: Neopixels and 2 Bluetooth boards

When using conductive thread none of the wires can overlap. With neopixels you have three wires – Ground, Power and Data. Three wires coming out of 15 lights in a close grid going to different pins on a board… it quickly became a nightmare to even try and plan this. Also neopixels are expensive.

Plan B: 15 LEDs and 2 Bluetooth boards

Sewable LEDs are cheap! All you do is turn them on or turn them off. The Bluetooth board I decided on is also really cheap. The WEMOS LOLIN32 board was only released 3 months ago but it looks perfect. Only available from China I ordered 2 and designed the plan for the grid:

jacket_planb

The + point of each LED connects to a IO pin on the board. Simples, right?

Plan C: Power consumption

While sitting around for my Bluetooth boards to arrive I looked at the grid again and figured out a better way to display the grid to save power. I got rid of the smiley face and brought the number of lights down to 11.

  • Lights 1, 4, 6, 8 and 11 are always on.
  • The left arrow would need to turn on 2, 7 and 9.
  • The right arrow would need to turn on 3, 5 and 10.

jacket_planc

Plan D: Alternate board?

I realised my package wasn’t actually on its way… I re-ordered it and twiddled my thumbs some more. I wondered how well the bluetooth boards would pair with each other every morning. I was in the middle of creating my micro:bit radio controlled belt and wondered about using the micro:bit to control the lights. The radio works really well on the belt, the micro:bit is small and sewable.

Nope: the IO pins of the micro:bit only provide 5ma of power. A simple LED need 11.

Plan E: Neopixels, LEDs and the micro:bit

I only need to control 6 lights. The rest of the lights can be connected directly to a power source as they’re always on. The micro:bit can’t power 6 LEDs but it can control 6 Neopixels.

  • 5 lights will be normal LEDs connected to an always on power source (sewable CR2032 battery?)
  • 6 lights are neopixels  chained together (indicated in blue below) with the data pins connected to the micro:bit

jacket_plane

That’s as far as I’ve got! I’ve ordered yellow LEDs. The trick will be matching the colour of the neopixels to the LEDs so it all works together.

Watch out for Plan F!

Advertisements

One thought on “FAIL: RGB LED Indicators for a Cycling Jacket

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s