#1: Cost.
Each face of the blink uses a single, super cheap LED for both TX and RX (six IR LEDs in total). The IR LED leads are connected directly to the pins of the microcontroller. There are no other parts associated with IR communications.
I do not think there is any other communications method that could meet the product requirements (minimum data throughput, minimum/maximum distance, being able to differentiate communication partners based on face location) that can come even within an order of magnitude on cost.
Additionally the current IR system is…
- Very low power (almost unmeasurable compared to the visible LEDs).
- Physically small (a single 0603 part per face).
- Flexible. I’ve done some fun stuff using the IR LEDs in creative ways. Someday someone could make a TV remote controller, or a motion detector, or self syncing animated fidget spinner (all things on my list!
).