It’s a foundation for a wearable platform. It’s a Nato watch strap threaded through a PCB with a coin cell battery holder between the PCB and the strap. I’m using a Attiny85 this time around but could be used for most chips/dev boards. This is a proof of concept to iron out any problems I’ve overlooked.
So you know when you have an idea kicking round in your head but there are a few problems to solve before you can make it. Well I wanted to make a wearable but was struggling with a way to do the strap, I was browsing aliexpress and came across a watch strap called the “nato”. This strap would let you thread it through a PCB and insulate it from your wrist.
- 4 1206 SMD LED’s
- 4 1206 220ohm resistors
- Ball tilt sensor
- CR2032 coin cell holder
- Nato watch strap
With this being a proof of concept I went with something simple. All this is a Attiny85 with 4 SMD LED’s and a ball tilt switch/sensor. I treated the ball tilt switch as a button so when it was “pressed” it enumerated the led number so It would go from LED 1 to 4 then back round to 1 again. When I was bread boarding this with 5mm LED’s It didn’t look like this would be bright enough but with the SMD LED’s it was fine.
I tried to use as many SMD parts as possible, After doing the design I wish I would have went with a smd attiny85, This way I wouldn’t have to make a pogo pin program and could use a chip clip like below.
Because I was putting the battery holder on the bottom of the board I was limited to where I could put the through whole parts so had to make the board a bit longer then I would have liked. Again this is why I should have used a SMD attiny85.
So like I said this is a foundation for a wearable, While I was doing the basic design I was exploring a few different avenues. The first thing that sprung to mind was to make a wrist mounted TV-B-Gone. I was going to use the Attiny85 version but after a lot of testing I couldn’t make it work on a single coin cell.
That is the problem with this foundation, you are limited to just one coin cell. Think I’m going to put this idea in my back pocket for a time when I think it will work. I hope this is an inspiration for someone out their.
So I’m using a bare bones Attiny85 for this project, While I was prototyping I made a backpack to clip over the top of the chip and into the breadboard. I made a blog post with more detail and board files HERE
To program the chip while it’s on the PCB you could break out a programming header on the PCB and solder some male pins onto or better still use pogo pins. The only problem with having to break out programming headers is space. With this project I didn’t have much so I decided to make a backpack that sat over the chip and have pogo pins that sit on top the chips legs. This is centered with male header pins on ether end of the chip like shown below. I use a cloths peg to hold it in place.