DIY Board¶
The DIY board is the original approach from Morgan Manly's design — discrete breakout modules wired together to drive each split-flap module's stepper motor.
Components (per module)¶
| Component | Purpose |
|---|---|
| PCF8575 I²C I/O expander | Receives commands from ESP32 over I²C, drives motor coil outputs |
| ULN2003 motor driver | Translates logic-level signals from the PCF8575 to the higher current needed by the stepper coils |
| 28BYJ-48 stepper motor | Drives the flap drum |
| Hall sensor | Detects the home magnet on the drum for zero-position calibration |
| Connecting wires | Link the breakout boards together |
Address configuration¶
The PCF8575 has three address pins — A0, A1, A2 — set via the onboard DIP switch or solder pads. Each module in a chain must have a unique address. See the I²C reference for the full address table.
Pull-up resistors
You must add 4.7kΩ pull-up resistors on SDA and SCL for the I²C bus to function. One set per bus is sufficient — add them on the first module in the chain. See the I²C reference for details.
Pros and cons¶
Pros:
- Low per-unit cost — parts are inexpensive and widely available
- Good for experimenting with a single module before committing to a full build
- No minimum order
Cons:
- More soldering per module — each board requires wiring multiple components together
- Bulkier than the custom PCB
- More points of failure (hand-soldered connections)
- Harder to replicate consistently across 8–16 modules