Clocktower LEDs

ECE 5730: Clocktower LEDs
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ECE 5730: Clocktower LEDs
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A prominent feature of Cornell’s iconic clocktower is the coloring of the
clock faces for special events, which
many students enjoy
However, the current controller for the clocktower is a small remote that
is less than ideal (with unclear controls, variable communication
strength, and lack of extensibility/advanced features).
For our project, we designed a custom LED controller system for the
clocktower. This system uses the existing LED lights, but uses a
distributed system involving 6 Raspberry Pi Pico W’s to configure
and drive the LEDs. With the system, Chimesmasters have the ability
to not only set a constant color with more control, but to also have
the lights change with ambient light and volume, and have the ability
to extend the system over WiFi/Bluetooth.
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© Copyright 2025, Aidan McNay, Edmund Lam, Qingmiao Xiao.
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Detailed Project Description

Clocktower LEDs is an embedded-systems build that integrates sensors, actuators, a microcontroller and firmware into one working device, with the design decisions and test results documented so it can be reproduced.

How It Works
1. Input devices (sensors, buttons, encoders, wireless links) are connected to the microcontroller.
2. Firmware samples the inputs at a fixed rate and runs the control/processing logic (often with interrupts, timers or PIO for precise timing).
3. Outputs (motors, LEDs, displays, audio, radio) are driven according to the result.
4. The system is tested against its specification and tuned for reliability and responsiveness.

Key Components and Their Role
- Raspberry Pi Pico (RP2040): dual-core Cortex-M0+ microcontroller with PIO state machines used for precise, low-level timing.
- RP2040: dual-core Cortex-M0+ microcontroller with programmable I/O used for precise, low-level timing.
- Raspberry Pi: single-board Linux computer that runs the higher-level processing and networking.
- Bluetooth Low Energy: short-range low-power wireless link to a phone or browser.

Implementation Steps
1. Collect the components and study each module's datasheet (pin-out, voltage, interface).
2. Wire the circuit on a breadboard following the pin mapping; power sensors from the correct rail (3.3 V / 5 V).
3. Install C, Arduino IDE and the required libraries; flash a minimal test sketch for each module separately.
4. Write the main firmware: read sensors → process → drive outputs / send data.
5. Configure network or cloud credentials and test communication end-to-end.
6. Calibrate thresholds, add error handling (reconnect, sensor time-out) and run a long-duration test.
7. Finalise on a PCB / enclosure and document wiring, code and results.

Key Features
- Real-time firmware
- Custom hardware integration
- Measured performance
- Documented design and trade-offs

Expected Output
On completion the student will have a demonstrable device that meets its functional specification, with wiring diagram, code and results.

Deliverables
- Complete source code with comments
- Circuit diagram and pin mapping
- Project report with screenshots and results
- Demonstration-ready build