Project Specification
Purpose
Compact battery-powered proximity-triggered actuator controller.
Core requirements
- ESP32-S3 module-based controller.
- TF-Luna LiDAR connected by UART and operating continuously.
- Two 18650 cells in series: nominal 7.4 V, 8.4 V full charge.
- Cells charged externally; no onboard charger.
- Onboard 2S battery protection including overcharge, undervoltage, overcurrent/short-circuit protection, and cell balancing.
- Drive a two-wire automotive door-lock actuator directly from the protected 2S pack.
- Low-profile MOSFET H-bridge replaces electromechanical relays due to the 10 mm total height limit.
- Trigger sequence starts as forward/push pulse, short neutral dead time, reverse/close pulse, then neutral.
- Firmware-adjustable timing and cycle count; future mode supports three rapid cycles.
- Hardware and firmware must prevent destructive shoot-through and enforce a maximum actuator-on timeout.
Mechanical constraints
- PCB no larger than 40 mm × 75 mm.
- Total assembled height, including PCB, components, connectors, and solder joints, no greater than 10 mm.
- External battery cells, external 8.4 V charger, TF-Luna, and actuator are off-board.
- Use low-profile SMD construction and low-profile cable connectors.
Preliminary power budget
- Actuator current is not specified by the seller. Design high-current path provisionally for 10 A short pulses and verify using a measured stall-current test before production.
- TF-Luna is continuous and will dominate standby load; size its supply from verified datasheet current.
- ESP32-S3 rail must support radio current peaks even if wireless features are initially unused.
- Derive regulated logic/sensor rails from the protected 2S pack using efficient switching regulation where required.
Interfaces
- TF-Luna: UART RX/TX plus verified supply voltage and ground.
- Actuator: two high-current outputs from H-bridge.
- Battery: B+, cell midpoint, B− for onboard 2S protection.
- Programming/debug: compact ESP32-S3 native USB or low-profile programming pads, selected to preserve the height envelope.
Validation criteria
- Schematic follows each selected IC datasheet reference circuit.
- Safe neutral state at boot, reset, brownout, and firmware crash.
- No H-bridge shoot-through under any MCU GPIO state.
- Current path and connectors tolerate the provisional 10 A pulse target.
- PCB fits 40 × 75 mm and every fitted component remains within 10 mm assembled height.
- Final motor-current rating remains provisional until the actuator stall current is measured.