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.

## 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:

- Activation distance: reliable trigger range was roughly ≈ 1 cm, smaller than expected.
- Material interference: the stapler’s metal body reduced the sensed magnetic field, impacting placement options.

Adjustments we made based on these results:

- Scope: focused on a single state — low staples — instead of continuous counting.
- Sensor placement: moved the Hall sensor to the side gap in the stapler where metal interference is lower.
- Magnet placement: shifted magnets to the top of the mechanism to improve readability and reduce interference.

## 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:

- Digital output: purely binary, similar to Makey Makey — not useful for level/strength.
- Analog output: varied, but behaved nearly binary in practice; likely due to sensor sensitivity and magnet strength.
- Outcome: we treated the sensor as an on/off low‑staple indicator.

Mechanical observations and placement notes:

- Magnet adhesion: too strong when spanning two metal walls; tuned magnet count so it adheres to one wall only.
- Spring clearance: the spring’s flex provided enough headroom — a small unexpected win.
- Low‑staple behavior: with very few staples, the magnet sometimes pulled staples; future fix could shield lateral surfaces.
- Calibration: aligned the Hall sensor to trigger near ~12–15 staples; angle/alignment is critical.

# 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:

- Use a larger stapler
- Use a smaller wireless board like ESP32 to house all boards in wire inside
- Use RED or YELLOW LED to indicate low status
- More than one Sensor to use original counting method
- Give metal body antimagnetic properties using a demagnetizer or coat of paint

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