Change Old to New — Penny/Nano Exchanger

James Coxon
Jun 24 · 3 min read
Credit — NanoIsSuperior

Theory:

Reports suggest that six in ten of UK 1p and 2p coins are only used once before being stored or discarded and one in twelve are thrown away¹. This has lead to regular reassessments of the role of small metal objects in modern non-digital currencies particular with a drive for an increasingly cashless society.

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:

The Penny/Nano Exchanger is a simple device: you scan your Nano address’ QR code and then insert your spare coins. The device counts up the value of the coins and sends you the equal amount in Nano. The device was first presented at the Nano UK Meet-up 2019.

How to use it:

  1. Scan your wallet’s QR code (the camera has a fixed focus so you might need to move it back and forth until it gets a good picture)
  2. The device will then display a scrolling address
  3. When it says GO start inserting your coins (Accepts 1p, 2p, 5p, 10p, 20p and 50p (not £1 or £2))
  4. If you stop inserting it will timeout after 10 seconds and send you Nano

How it works:

Components

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. Supermarkets and Stores — just a place to convert spare change into Nano
  2. Airports — on return you can get rid of your spare change from overseas.
  3. Nano Arcade

Code and 3D Files


The Nano Center

The Nano Center was created to spread the ingenuity and innovation of the Nano currency to a global audience. Our primary function is to assist all Nano enthusiasts in building, funding, and implementing projects related to Nano.

James Coxon

Written by

The Nano Center

The Nano Center was created to spread the ingenuity and innovation of the Nano currency to a global audience. Our primary function is to assist all Nano enthusiasts in building, funding, and implementing projects related to Nano.

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