Wireless bitcoin price display

Having aquired one of these adafruit feathers which has a built-in ESP8266 wifi module, I thought I'd put it to the test. I had never used the ESP8266 module before, but I have heard a lot about them and so I thought I'd try and create something small that would test its capabilities. If successful, I could then consider using this board (or just a regular arduino hooked up to an ESP6288 module) in place of a full Raspberry Pi setup when I want to incorporate wifi into projects.

The projects aim was to display the current bitcoin price in binary over some rows of LEDs.

After reading up on the module, I setup a nodeJS server to practice some HTTP requests and get the board working.

I then needed to find a lightweight website that would allow me to extract the current price. I came across this coindesk json api

After succesfully working out a way of extracting the price from that (GitHub), I then worked on the LED display aspect. The price of bitcoin was roughly £8000, but having spiked on the 16th December, 2017 to £14,592, I would need 14 bits to be able to safely display the full price (allowing me up to 2^14-1 which is 16383).

However, as seen in the pinout of the board below, there were only 9 pins available, so with 14 leds, I would need an alternative method to a pin per LED. I soldered them into a grid circuit (two rows of 7 leds) which would allow me to scan back and forth between the rows at a high speed and create the impression that the LEDs are constantly on. For this, I would then only need 8 of the 9 pins.

I tested the circuit with some jumpers:

I then just needed to finish writing the code (GitHub) and connnect an old 1S lipo from a quadcopter and it was working!

Here are some photos of the finished thing. (the price at the time was: 01111110100110 which is £8102).