5.1 KiB
5.1 KiB
Bill of Materials (BOM)
This bill of materials lists the components currently required or planned for OpenParcelBox.
Reused Boks One parts are separated from new components to make reverse engineering and PCB design easier to track.
Main Controller
| Reference | Description | Quantity | Status |
|---|---|---|---|
| XIAO-NRF52840 | Seeed Studio XIAO BLE nRF52840 | 1 | Validated |
Reused Boks One Parts
| Description | Quantity | Status |
|---|---|---|
| Front panel | 1 | Reused |
| KR-S79 lock mechanism | 1 | Reused |
| Battery compartment, 8x AAA | 1 | Reused |
| Internal wiring | As needed | Reused when suitable |
Keypad
The original keypad PCB is replaced by a new PCB compatible with the original front panel.
| Description | Quantity | Status |
|---|---|---|
| Push buttons | 12 | New PCB |
| 2x6 physical keypad layout | 1 | Planned production layout |
| 4x4 development matrix keypad | 1 | Validated for firmware development |
NFC
The nRF52840 integrated NFCT peripheral is tag-side NFC-A hardware and is not a standalone active reader for passive badges.
Badge UID reading uses a PN532 I2C module during development. A production PCB implementation still needs placement, range, antenna, and interference validation.
| Description | Quantity | Status |
|---|---|---|
| PN532 NFC/RFID I2C module with antenna | 1 | Integrated for development |
| Production NFC reader implementation | 1 | To design from PN532 validation |
Lock Control
The lock opens when a positive 8 to 24 V pulse is applied to the SIG input.
| Reference | Description | Quantity | Status |
|---|---|---|---|
| S8050 NPN + S8550 PNP stage | Development SIG high-side driver |
1 each | Integrated for development |
| Bias resistors | Development transistor stage | 4 | Integrated for development |
| Production high-side driver | Final SIG input driver |
1 | To select after validation |
Indicators and Audible Feedback
The original PCB LEDs are not considered reusable in the current plan.
| Description | Quantity | Status |
|---|---|---|
| Red LED | 1 | To select |
| Green LED | 1 | To select |
| Blue LED | 1 | To select |
| Active 3.3 V buzzer | 1 | Validated |
| Buzzer transistor driver | 1 | Validated concept |
Power Supply
| Reference | Description | Quantity | Status |
|---|---|---|---|
| 12 V to 5 V buck converter | DC/DC converter | 1 | To select |
| Battery voltage measurement circuit | Battery monitor | 1 | To design |
| Power protection circuit | Input protection | 1 | To define |
Electrical Protection
| Reference | Description | Quantity | Status |
|---|---|---|---|
| TBD | Reverse-polarity protection | 1 | To select |
| TBD | ESD protection | TBD | To select |
Connectors
| Reference | Description | Quantity | Status |
|---|---|---|---|
| TBD | Keypad connector | 1 | To define |
| TBD | Lock connector | 1 | To define |
| TBD | Battery connector | 1 | To define |
PCB
| Reference | Description | Quantity | Status |
|---|---|---|---|
| OPB-PCB-V1 | OpenParcelBox main board | 1 | In design |
Hardware Constraints
Power Supply
- Power is provided by the original 8x AAA battery pack.
- The lock is powered directly by the battery pack.
- The Seeed Studio XIAO is powered through a 12 V to 5 V buck converter.
- A common ground is used across the whole system.
Lock
- Supply: 8x AAA battery pack.
- Opening command: positive pulse on
SIG. - Opening validation:
COM/NCstate change. - A fixed delay must not be used as the only opening confirmation.
Keypad
- Production physical layout: 2x6.
- Development keypad: 4x4 matrix.
- The production keypad will use a custom PCB compatible with the original front panel.
NFC
- Do not rely on the nRF52840 NFCT peripheral for passive badge UID reading.
- Validate the PN532 module for badge-unlock range and interference.
- Integrate and tune the NFC reader antenna on the production PCB.
Remaining Decisions
High priority:
- Production implementation based on PN532 validation.
- NFC reader antenna design.
- High-side lock driver selection.
- Buck converter selection.
- LED selection.
- Battery measurement circuit design.
Medium priority:
- Connector selection.
- PCB placement.
- ESD protection.
Low priority:
- Power optimization.
- Component count reduction.
- Compatibility with other hardware variants.
Validation History
V0
- Seeed Studio XIAO BLE nRF52840 selected.
- Zephyr RTOS selected.
- Zigbee communication selected.
- Original front panel retained without irreversible modification.
- KR-S79 lock mechanism retained.
- 8x AAA battery compartment retained.
- Opening validation through
COM/NCselected. - Lock command through a positive pulse on
SIGselected. - Production keypad planned as a 2x6 physical layout on a custom matrix PCB.
- nRF52840 integrated NFCT identified as tag-side NFC-A hardware, not the passive badge reader path.
- Active buzzer selected and validated through a transistor driver.
- XIAO power through a 12 V to 5 V buck converter selected.