Change Old to New — Penny/Nano Exchanger

James Coxon
Jun 24, 2019 · 3 min read
Credit — NanoIsSuperior

Theory:

So instead of leaving your small change in a jar, why not convert it quickly and easily to a cutting edge global cryptocurrency and start using it for more than just a way of making your pockets jingle.

Nano provides the perfect digital currency for this project, you can easily transact tiny amounts of the currency across the globe, online and offline.

What is it:

How to use it:

  1. The device will then display a scrolling address
  2. When it says GO start inserting your coins (Accepts 1p, 2p, 5p, 10p, 20p and 50p (not £1 or £2))
  3. If you stop inserting it will timeout after 10 seconds and send you Nano

How it works:

Setup

The CH926 Coin Acceptor is a cheap chinese replacement coin acceptor, they are easily available on Ebay and Amazon and have been used in a number of maker/hack projects. The acceptor has its own internal microprocessor and can be setup to distinguish 6 different coins. While the primary interface is through a system of pulses (for example 2 pulses for 2p coin) this setup is not robust². Instead a more robust hack is to interface with the 6 leds on the CH926’s PCB which are linked directly to each coin type. The Raspberry Pi is interfaced to these LEDs and through the use of GPIO interrupts can detect when the LED illuminates and therefore register the coin.

The Raspberry Pi Zero W uses the Zero Cam to take a chain of pictures, each picture is run through a QR code detecting algorithm, if a valid Nano QR code is detected then the Raspberry Pi signals the user to start inserting the coins and monitors the CH926 LEDs adding up the value. The system has a 10 second timeout to allow detection of when the user has finished inserting coins, the total value is summed and then converted to Nano using the price from the CoinGecko API. Finally, the Nano is sent from the exchanger’s hot wallet using a light wallet interface, the exchanger does not have its own independent Nano node.

All the software including taking images, scanning for QR codes and then monitoring the GPIO interrupts for coin insertion is through a single python script.

Interfaces

Possible Use Cases

  1. Airports — on return you can get rid of your spare change from overseas.
  2. Nano Arcade

Code and 3D Files

The Nano Center

Spreading Global Economic Equality

The Nano Center

The Nano Center is a community organization which seeks to promote economic quality across the globe.

James Coxon

Written by

The Nano Center

The Nano Center is a community organization which seeks to promote economic quality across the globe.