# ESP32 Wearable Haptic Controller BOM

This is a portfolio sample BOM for the inspectable motor-driver boundary. Parts are representative values for schematic review and simulation alignment; they are not a released production AVL.

| Ref | Description | Representative value | Review note |
| --- | --- | --- | --- |
| J1 | ESP32 GPIO header | GPIO / GND | Keeps the control boundary explicit and reviewable |
| R1 | MOSFET gate resistor | 220 ohm | Limits GPIO edge current and damps gate ringing |
| R2 | Gate pulldown | 100k | Holds the motor off during reset or high-impedance GPIO state |
| Q1 | Logic-level N-channel MOSFET | AO3400A-equivalent | Must be checked for low Rds(on) at 3.3 V gate drive |
| J2 | Vibration motor connector | 2-pin | Motor modeled as R-L load in Ngspice |
| D1 | Flyback diode | SS14-equivalent | Cathode to VBAT, anode to MOSFET drain/motor low side |
| C1 | Local decoupling capacitor | 10 uF | Place near motor/supply connector to reduce supply dips |
| J3 | Battery/input connector | VBAT / GND | Review current loop and ground return before layout |

## Human Review Notes

- Q1 gate threshold must not be treated as the fully enhanced operating point.
- The flyback diode orientation is safety-critical for inductive load switching.
- The motor current loop should be short and separated from sensitive ESP32 references where practical.
- Battery charging, fuel gauge, enclosure, and sensor subsystems are outside this first evidence boundary.