VEX IQ Automated Coin Management System

C++Embedded ControlLaser Cutting3D PrintingSensor Calibration

A multi-user automated coin ATM built from VEX IQ parts, a laser-cut HDF frame and 3D-printed drivetrain parts, controlled by a 700+ line C++ program.

Coin-detection accuracy: 96.7%
Withdrawal accuracy: 100%
Avg. jam-detection response: 0.41 s

Overview

I designed and fabricated a multi-user automated coin ATM using VEX IQ components, a laser-cut HDF frame, and 3D-printed drivetrain parts, managing the build and the software integration across a 4-person team.

The finished Stash&Store ATM on a table, with coin slot, screen and coin tray — The finished machine: coin slot, screen and coin tray.

SolidWorks model of the ATM enclosure with coin slot, screen opening and tray opening — The enclosure modeled in SolidWorks.

Mechanism

The internal layout was modeled in SolidWorks before anything was cut.

SolidWorks model of the full internal assembly: brain, coin channel, ramp and tray — Internal assembly in SolidWorks.

Close-up of the VEX IQ brain and the coin channel in the SolidWorks model — Close-up of the VEX IQ brain and the coin channel.

Close-up of the SolidWorks model of the coin ATM mechanism — Close-up of the SolidWorks model.

Software architecture

I architected a 700+ line C++ embedded program around a centralized state struct. It runs 7 operating modes at about 50 Hz and provides PIN authentication, tamper detection, overdraw prevention, and session timeout, with deterministic control behaviour.

Results

Optical-sensor calibration gave 96.7% coin-detection accuracy, with 100% withdrawal accuracy across all test trials and a 0.41 s average jam-detection response, all verified against ASTM-style test procedures.