Bill of Materials (BOM) - Etwow GT Auto-lock System
📋 Core Electronics
| Component |
Quantity |
Part Number |
Description |
Supplier |
Price (Est.) |
| ESP32-S3 Dev Board |
1 |
ESP32-S3-DevKitC-1 |
3.3V logic, BLE central, 2×UART |
Espressif/Digi-Key |
$15-20 |
| nRF52810 Module |
1 |
MDBT40-ATR |
BLE badge transmitter |
Raytac/Digi-Key |
$8-12 |
| CR2032 Battery |
1 |
CR2032 |
3V lithium coin cell |
Generic |
$2-3 |
| CR2032 Holder |
1 |
CR2032-TH |
Through-hole battery holder |
Generic |
$1-2 |
⚡ Power & Connectivity
| Component |
Quantity |
Part Number |
Description |
Supplier |
Price (Est.) |
| DC-DC Buck Converter |
1 |
LM2596S-5.0 |
6-60V to 5V step-down |
Generic |
$3-5 |
| LDO Regulator |
1 |
AMS1117-3.3 |
5V to 3.3V linear regulator |
Generic |
$1-2 |
| JST-PH Connectors |
2 sets |
JST-PH-4P |
Inline UART connector set |
JST/Digi-Key |
$5-8 |
| Dupont Jumpers |
10 |
Female-Female |
Temporary inline coupling |
Generic |
$3-5 |
| Power Connector |
1 |
JST-XH-2P |
2-pin power connector |
JST |
$2-3 |
🔧 Signal Processing
| Component |
Quantity |
Part Number |
Description |
Supplier |
Price (Est.) |
| Tri-state Buffer |
1 |
74LVC1T45 |
Single-bit bidirectional buffer |
TI/Digi-Key |
$2-3 |
| Hall Sensor |
2 |
SS495A |
Analog Hall-effect sensor |
Honeywell |
$8-10 |
| MOSFET |
1 |
BSS138 |
N-channel logic-level MOSFET |
Infineon |
$1-2 |
| Decoupling Caps |
3 |
100nF + 10µF |
Ceramic + electrolytic |
Generic |
$2-3 |
| Resistor Pack |
1 |
0603/0805 |
Assorted values (1k, 10k, etc.) |
Generic |
$5-8 |
🛠️ Programming & Debug
| Component |
Quantity |
Description |
Supplier |
Price (Est.) |
|
| USB-C Cable |
1 |
Data cable for ESP32 programming |
Generic |
$3-5 |
|
| USB-TTL Adapter |
1 |
CP2102/FT232RL |
UART debugging (optional) |
Generic |
$5-8 |
| SWD Programmer |
1 |
J-Link EDU |
nRF52 programming (optional) |
SEGGER |
$60+ |
| Jumper Wires |
1 set |
Male/Female mix |
Breadboard connections |
Generic |
$5-8 |
🏠 Mechanical & Enclosure
| Component |
Quantity |
Description |
Supplier |
Price (Est.) |
|
| Enclosure |
1 |
100×60×30mm |
Water-resistant plastic case |
Generic |
$5-10 |
| PCB Headers |
2 sets |
2.54mm pitch |
Locking connectors |
Generic |
$3-5 |
| Heat Shrink |
1 |
Various sizes |
Wire protection |
Generic |
$3-5 |
| Zip Ties |
10 |
Various sizes |
Cable management |
Generic |
$2-3 |
| Double-sided Tape |
1 roll |
Foam tape |
Mounting |
Generic |
$2-3 |
💰 Total Cost Estimate
- Core Electronics: $25-35
- Power & Connectivity: $15-25
- Signal Processing: $15-20
- Programming & Debug: $15-25
- Mechanical & Enclosure: $15-25
Total Project Cost: $85-130
📝 Notes
Voltage Considerations
- Scooter Battery: Typically 36V or 48V
- Buck Converter: Must handle input voltage range (6-60V recommended)
- Logic Levels: All digital I/O at 3.3V
Connector Compatibility
- UART Connector: Verify JST-PH pinout matches Etwow GT display/BT module
- Power Connector: JST-XH recommended for battery connections
- Programming: USB-C for ESP32, SWD for nRF52 (optional)
Sourcing Recommendations
- Primary: Digi-Key, Mouser for reliable components
- Secondary: Amazon, AliExpress for generic parts
- Local: RadioShack, electronics stores for basic components
Quality Considerations
- ESP32-S3: Get official Espressif board for best compatibility
- nRF52810: Raytac MDBT40 series is well-supported
- Connectors: JST brand recommended for reliability
- Buck Converter: LM2596S is proven and reliable
🔄 Alternatives & Substitutions
ESP32 Alternatives
- ESP32-C3 (smaller, single-core)
- ESP32-WROOM-32 (older but cheaper)
nRF52 Alternatives
- nRF52811 (more features, higher cost)
- nRF52832 (larger package, more GPIO)
Power Alternatives
- Linear regulator (simpler, less efficient)
- Switching converter with enable pin (better power management)
Connector Alternatives
- Terminal blocks (easier wiring, less professional)
- Wire-to-wire crimp connectors (cheaper, less reliable)