1.9 KiB
Hardware Interfaces
This document describes the hardware interfaces independently from the GPIO assignments used by a specific board revision.
Keypad
Production target:
- Vertical 2x6 physical layout.
- Matrix keypad implemented on a custom PCB.
Development target:
- Freenove 4x4 matrix keypad.
- PCF8574 GPIO expander.
Features:
- Software debounce.
- Key press detection.
- Zephyr-compatible driver.
NFC Reader
The nRF52840 integrated NFC controller is the preferred design path.
Functions:
- UID reading.
- Badge validation.
- Unlock request trigger.
The antenna and matching network still need to be designed and validated.
KR-S79 Lock
Command:
- Positive pulse on
SIG.
Validation:
The firmware must not validate opening based on a fixed delay.
Opening validation relies on the COM/NC contact state change.
Sequence:
SIG command
|
Opening pulse
|
Wait for COM/NC
|
+-- State change detected: opening confirmed
|
+-- Timeout: opening error
RGB LEDs
The original front LEDs are not considered reusable in the current hardware plan.
The new PCB will provide replacement red, green, and blue indicators.
Buzzer
The buzzer provides audible feedback.
The current validated design uses an active buzzer driven through a transistor.
Examples:
- Key press feedback.
- Opening confirmed.
- Error feedback.
- Diagnostic feedback.
Battery
The original battery compartment is retained.
The firmware will provide:
- Voltage measurement.
- Battery level estimation.
- Low battery alerts.
Zigbee
OpenParcelBox is intended to communicate natively with Home Assistant over Zigbee.
The firmware should not depend directly on an MQTT broker.
Zigbee integration may be exposed through:
- ZHA.
- Zigbee2MQTT.
OTA
Updates must be performed securely.
Each firmware image must be verified before installation.