Build a coin counter from particleboard and a Pi Pico
Feed the Meter
© Lead Image © Andrey Burmakin, 123RF.com
Parking meters and vending machines detect and count the coins you insert, but how do they work? We'll show you how to mimic the functionality with some particleboard, a Raspberry Pi Pico, a few extra chips, and some Python code.
Counting coins is a problem that was solved decades ago, but I was wondering whether I could come up with a solution of my own. While I may not have the same set of sophisticated tools that a parking meter manufacturer has, it should certainly be possible to create an electronic coin counter using just a Raspberry Pi Pico and some common components. Writing software that can count is trivial, but how do you detect what type of coin was inserted? If you assume that only legal US coins will be used, the easiest way to recognize them is by measuring their diameter. Table 1 lists the diameters of US coins, both in millimeters and in inches [1].
I decided to sort the coins using different sized slots. The coins roll down a small ramp and pass several cut-out slots. If the coin is the correct size, it falls through the slot. The required width of the slot depends on how fast the coin is rolling past whereas the height of the slot needs to be slightly larger than the actual coin while still being smaller than the next largest coin. In my case, the slots were approximately twice the width of the coin (see Figure 1).
[...]
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
US / Canada
UK / Australia
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Support Our Work
Linux Magazine content is made possible with support from readers like you. Please consider contributing when you’ve found an article to be beneficial.
News
-
Kali Linux 2025.3 Released with New Hacking Tools
If you're a Kali Linux fan, you'll be glad to know that the third release of this famous pen-testing distribution is now available with updates for key components.
-
Zorin OS 18 Beta Available for Testing
The latest release from the team behind Zorin OS is ready for public testing, and it includes plenty of improvements to make it more powerful, user-friendly, and productive.
-
Fedora Linux 43 Beta Now Available for Testing
Fedora Linux 43 Beta ships with Gnome 49 and KDE Plasma 6.4 (and other goodies).
-
USB4 Maintainer Leaves Intel
Michael Jamet, one of the primary maintainers of USB4 and Thunderbolt drivers, has left Intel, leaving a gaping hole for the Linux community to deal with.
-
Budgie 10.9.3 Now Available
The latest version of this elegant and configurable Linux desktop aligns with changes in Gnome 49.
-
KDE Linux Alpha Available for Daring Users
It's official, KDE Linux has arrived, but it's not quite ready for prime time.
-
AMD Initiates Graphics Driver Updates for Linux Kernel 6.18
This new AMD update focuses on power management, display handling, and hardware support for Radeon GPUs.
-
AerynOS Alpha Release Available
With a choice of several desktop environments, AerynOS 2025.08 is almost ready to be your next operating system.
-
AUR Repository Still Under DDoS Attack
Arch User Repository continues to be under a DDoS attack that has been going on for more than two weeks.
-
RingReaper Malware Poses Danger to Linux Systems
A new kind of malware exploits modern Linux kernels for I/O operations.