Home Module 2 Activity 1 Activity 2 Activity 3 Project 2

Module 2 Activity Research

Weekly Activity for Staple Monitor

Jesse Keo & Rajatpal Singh Sodhi


Project 2


Module 2

A Staple Monitor that notifies you when you are running low on staples using a microcontroller and Halls Effect Sensor.

Activity One

The first activity of this project was mainly research and exploration. In our research for possible sensors that would measure the number of staples we mainly looked at two methods: a button to count the staple press and a sensor to measure the number of staples. In the end we chose a sensor method after some discussions about misfires as we concluded that a sensor would be able to account for any staple misfires while a button couldn’t. The sensor we researched was a Halls Effect sensor where when a magnet would reach close to it the sensor would activate and measure the magnetic strength. In the YouTube video we saw, we also found that it measured the magnetic strength based on distance between the magnet and sensor and had an idea to use those individual numbers as our activation points for our stapler count.

With some research done, we moved onto exploration. Because the main components of our idea required a magnet and a halls effect sensor to measure how many staples there were in a stapler, the first thing we did was inspect staplers.

We bought two different staplers and took them apart to look for points where a sensor and magnet could be put in without affecting the stapler’s ability to staple. We also explored locations where we could house the wires and boards to keep them hidden in future iterations as well.

The stapler we selected for our project - chosen for its compact size and simpler design with fewer components, making it ideal for sensor integration Disassembling the stapler to inspect the internal mechanism and component layout Further disassembly and identifying precise locations for the Hall Effect sensor Researching Hall Effect sensor setups with ESP32/Arduino for integration Exploring internal space to route wires and house boards

Activity Two

For our second activity we did some guerilla prototyping with a Hall Effect sensor, Makey Makey, and a breadboard. We initially wanted to use an Arduino but couldn’t borrow one in time, so we used the Makey Makey instead. With help from ChatGPT, we wired the Hall sensor so that each activation pressed a key on the keyboard.

We then tested the setup and captured findings:

Adjustments we made based on these results:

Initial guerilla prototype: Makey Makey connected to a Hall Effect sensor on a breadboard for quick feasibility testing Close-up of wiring the Hall Effect sensor into Makey Makey inputs and ground for keyboard-trigger tests Measuring activation distance — bringing a magnet toward the sensor to observe at what range it triggers Metal stapler body causing magnetic interference, leading to a repositioned layout — sensor moved to the side gap and magnet to the top to reduce interference and improve reliability Makey Makey test: magnet detection triggers the 'W' key input on the keyboard Reference diagram generated with ChatGPT outlining Makey Makey–Hall Effect wiring and signal flow

Activity 3

With an Arduino we moved to reading magnetic strength rather than Makey Makey’s binary touch model. Using a short tutorial as a base and a few modifications, we displayed the sensor’s strength readings.

Signal testing highlights:

Mechanical observations and placement notes:

Arduino test rig measuring magnetic strength via the Hall sensor’s analog output Testing magnet polarity: comparing north vs. south pole orientation to decide magnet placement inside the stapler and optimal Hall sensor positioning Arduino digital‑pin trial: binary output unstable/noisy, confirming digital mode is not reliable for this sensor Serial Monitor evidence of missed detections — magnet proximity not consistently registered, motivating analog‑output approach and alignment tweaks Tuning magnet count and placement so the magnet holds to one wall yet still triggers reliably Hot‑gluing magnets to the black bar attached to the spring so the magnets travel with the mechanism without interfering with the staples Checking magnets, spring action, and staple stack for side‑effects on sensor readings Low‑staple calibration and integration: aligning the Hall sensor to trigger around ~12–15 staples, then finalizing sensor/magnet placement with Arduino wiring for end‑to‑end validation

Project 2 Prototype


Our Staple Monitor prototype was able to hold approximately 50 staples at full capacity and indicate its low status at 14 staples with an LED light to indicate it's status. We tested the stapler three times and found that the light indicated a low staple amount at a fairly accurate rate. As a prototype we think it was successful in showing our proof of concept. Moving forward we would like to implement:

Final setup of the Staple Monitor prototype showing overall assembly Close‑up of Arduino Uno: Hall‑sensor connector and alligator clip ends hot‑glued/insulated to prevent shorts when contacts touch Internal wiring and board placement inside the stapler; repeated tests showed the LED reliably indicates a low staple count Video demo: when staples drop below ~15, the low‑staple LED turns on
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