Carnegie Mellon ECE Capstone, Fall 2025 – Safiya Bainazar, Tedd Jung, Crystal Huang
This week I started getting the STM32 setup by configuring the timers and GPIO pins to generate a PWM signal. This has not been successful yet, but I will verify the setup by output putting the PWM signal to an LED.
I am slightly behind on schedule due to workload from other classes. I will put in extra hours this weekend to get the LED to vary in brightness with duty cycle, demonstrating the PWM signal.
Next week I hope to be able to have 4 servos moving in parallel.
This week I continued designing the actuator subsystem of the project. We decided to use a RC servos to power rack and pinions that will actually push the pins. However, each servo would need their own continuous PWM signal and using 32 independent channels directly on one STM is impractical. This means we need an external PWM driver IC.
We are still on schedule. We hope to order parts by the end of next week.
So far, I’ve worked on shaping the project by carefully identifying the right components and mechanisms to make it feasible. I started by analyzing the cost and scalability issues of giving each pin its own actuator, realizing that this would exceed our $600 budget, so I explored alternatives like row-based actuation and column scanning. This week I listed different position based actuator parts we could use and narrowed it down to a few. On the electronics side, I mapped out how to divide responsibilities between a Raspberry Pi (for real-time depth capture and heightmap processing) and an STM32 (for deterministic actuator control), since the Pi can’t handle precise timing and the STM32 can’t handle heavy vision workloads. I also investigated specific ways to test latency, weighing options like software timestamps versus high-speed video, to ensure I can measure each subsystem’s delay as well as the full end-to-end pipeline.