Product description
Goal
The production phase converts the pilot design into hardware that Gratheon can sell and support. The priority changes from cheapest parts to repeatability, calibration, enclosure quality, supply-chain stability, and remote diagnostics.
This phase can still use ESP32-class hardware, but it should move toward pre-assembled wiring, a PCB or carrier board, a calibrated mechanical frame, and a clean pairing flow in the web app.
Functionality
- Factory-calibrated load-cell frame or repeatable calibration process.
- Pre-flashed firmware with device identity and secure pairing.
- Battery and solar subsystem sized for months of operation.
- Waterproof connectors and strain relief for field servicing.
- Device health telemetry: battery, RSSI, firmware version, last seen, reset reason, and enclosure temperature where useful.
- Optional LoRa/ESP-NOW apiary gateway for multiple hives without WiFi.
- Optional cellular gateway or cellular device variant for remote single-hive deployments.
- Supportable replacement parts and documented mechanical tolerances.
Production architecture
flowchart LR
subgraph ScaleFrame[Calibrated scale frame]
loadpath[Top plate, load path, overload stops]
loadcell[Load cell]
end
subgraph Enclosure[IP65/IP67 electronics enclosure]
pcb[ESP32 carrier PCB]
adc[HX711 or 24-bit ADC]
power[Protected battery, charger, fuse, switch]
fuel[Fuel gauge and solar sense]
service[Debug and factory-programming header]
end
ds18b20[Replaceable DS18B20 probe]
ambient[Replaceable ambient sensor pod]
solar[Solar panel]
gateway[Optional apiary gateway]
telemetry[telemetry-api]
loadcell -- shielded load-cell cable --> adc
adc --> pcb
ds18b20 -- M8 3-pin or gland --> pcb
ambient -- short I2C cable or sensor pod --> pcb
solar -- keyed power connector --> power
power --> pcb
fuel --> pcb
pcb -- WiFi or local radio --> gateway
pcb -- WiFi HTTPS when available --> telemetry
gateway -- HTTPS batch upload --> telemetry
Connector strategy
Production should use connectors to make field parts replaceable without opening solder joints. The exact connector family can change, but the interface count should be stable.
| Interface | Pins | Suggested connector | Signals | Service reason |
|---|---|---|---|---|
| Load cell | 4 or 6 | M12 4-pin/5-pin, sealed gland for early production | E+, E-, A+, A-, optional shield/sense | Load cell or frame can be replaced after mechanical damage. |
| DS18B20 internal probe | 3 | M8 3-pin or waterproof inline connector | 3.3 V, GND, 1-Wire data | Probe can be replaced if damaged by bees, tools, or moisture. |
| Ambient sensor pod | 4 | M8 4-pin or short sealed internal harness | 3.3 V, GND, SDA, SCL | Humidity sensor can be replaced when it drifts or corrodes. |
| Solar panel | 2 | Keyed waterproof 2-pin connector | Solar +, solar - | Prevents reversed polarity and simplifies seasonal replacement. |
| Battery pack | 2-3 | Internal keyed connector | Battery +, battery -, thermistor if used | Safe factory assembly and service swap. |
| Debug/programming | 4-6 | Internal JST or pogo pads | 3.3 V, GND, UART TX/RX, EN/BOOT | Factory flashing and support without exposing USB outdoors. |
| Gateway radio antenna | 1 | SMA/u.FL only if needed | RF | Keep only for LoRa/cellular variants. |
Electrical design requirements
| Area | Requirement | Reason |
|---|---|---|
| Grounding | Keep analog load-cell ground and digital ground controlled on PCB. | Reduces weight noise and support tickets. |
| Load-cell routing | Differential signal traces should be short, paired, and away from switching power. | Load-cell output is a low-level analog signal. |
| Protection | Add input protection on external sensor and power lines. | Outdoor cable runs can receive ESD and wiring mistakes. |
| Power switch | Provide a user-visible power/service switch or magnetic reed option. | Beekeeper needs a clear safe state during installation. |
| Fuse/protection | Battery and solar input need current limiting and reverse-polarity protection. | Reduces fire and support risk. |
| Battery telemetry | Include fuel gauge or calibrated voltage divider plus solar input sensing. | Enables proactive low-battery alerts. |
| Firmware identity | Store unique deviceId, firmware version, and hardware revision. |
Required for pairing, diagnostics, and recalls. |
| Watchdog/reset reason | Report reset reason after every reboot. | Distinguishes brownout, crash, and planned firmware update. |
Mechanical production requirements
The scale mechanics must be treated as a product subsystem, not as a generic bracket.
| Requirement | Practical implementation |
|---|---|
| Repeatable load path | Top plate should transfer hive weight through intended load-cell points only. |
| Overload protection | Add mechanical stops before the load cell reaches destructive deflection. |
| Side-load protection | Add guides or frame geometry that resist hive sliding without bypassing the load cell. |
| Water drainage | Avoid pockets around the load cell, bolts, and cable exits. |
| Corrosion resistance | Use aluminium, stainless, galvanized, or coated parts appropriate for wet apiaries. |
| Calibration access | Calibration should not require disassembling the frame. |
| Cable protection | Route load-cell cable through protected channels or clips away from hive tools and rodents. |
| Service labeling | Label frame orientation, max load, serial number, and calibration date. |
Chip and connectivity recommendation
Start with ESP32-WROOM DevKit
Use a standard ESP32-WROOM DevKit for lab and field MVP because it is cheap, familiar, Arduino-compatible, and already used by the prototype. It has enough RAM/CPU for local filtering, WiFi provisioning, TLS HTTP requests, and deep sleep.
Production variants
| Variant | Use when | Recommendation |
|---|---|---|
| ESP32-WROOM module | Base production node with WiFi in range | Default production MCU if field MVP is stable. |
| ESP32-C3 | Lower cost/power, single-core is enough | Good second board after firmware is stable. |
| ESP32-S3 | Need more RAM, USB, or future TinyML/audio experiments | Use for acoustic/edge ML prototypes, not base scale. |
| ESP32 + LoRa | Remote apiary with no WiFi but multiple hives nearby | Production gateway architecture. |
| ESP32 + SIM7080/SIM7000 LTE-M/NB-IoT | Single remote hive without WiFi/LoRa gateway | Later paid/field kit; raises cost and power complexity. |
| nRF52/STM32/RP2040 | Custom PCB or ultra-low-power redesign | Defer until there is field data from ESP32 MVP. |
Decision rule: WiFi first, LoRa gateway second, cellular last. Cellular is attractive commercially but too expensive and power-sensitive for a low-friction DIY launch.
Production remote-apiary architecture
flowchart LR
node1[Hive node 1<br/>ESP32 + sensors] -- ESP-NOW/LoRa --> gateway[Apiary gateway<br/>ESP32/Raspberry Pi/cellular]
node2[Hive node 2<br/>ESP32 + sensors] -- ESP-NOW/LoRa --> gateway
node3[Hive node N<br/>ESP32 + sensors] -- ESP-NOW/LoRa --> gateway
gateway -- HTTPS batch upload --> telemetry[telemetry-api]
telemetry --> web[Gratheon web app]
This keeps the first kit simple while preserving a path to remote apiaries: many cheap hive nodes, one internet-connected gateway.
Production telemetry checklist
| Field | Required for base kit | Why |
|---|---|---|
weightKg |
Yes | Main product value. |
temperatureCelsius |
Yes | Colony and sensor context. |
humidityPercent |
Yes | Moisture risk and ambient context. |
batteryVoltage |
Yes | Basic support signal. |
batteryPercent |
Recommended | Easier for beekeeper alerts. |
solarVoltage |
Recommended for solar SKU | Detects panel/cable failure. |
rssi |
Yes | Explains missing uploads and weak WiFi. |
firmwareVersion |
Yes | Support and rollout management. |
hardwareRevision |
Yes | Links telemetry to PCB and frame revision. |
resetReason |
Yes | Detects brownout and firmware crashes. |
calibrationId |
Recommended | Links data to factory or field calibration event. |
Quality and acceptance tests
- Rain simulation or hose splash test appropriate to the claimed IP rating.
- 24-72 hour soak test with telemetry upload, sleep cycles, and battery logging.
- Known-weight calibration test at low, middle, and high expected hive loads.
- Corner-load test for frame repeatability.
- Cable pull/strain-relief inspection.
- Power reverse-polarity and low-battery behavior test.
- Pairing test from unboxed device to Gratheon hive dashboard.
- Firmware update or recovery test if OTA is supported.
Research references
Research backing has moved to 🧪 Research references. It links this production-kit scope to Gratheon's Research section and explains why multimodal sensing, gateway connectivity, calibrated mechanics, and serviceable outdoor hardware shape the production roadmap.
Exit criteria
- Two or more identical units produce comparable weight trends after calibration.
- Device can be paired to a Gratheon hive without manual database edits.
- Support can see battery, RSSI, firmware version, last seen, and reset reason.
- Enclosure and connectors can survive realistic rain, UV, and service handling.
- Supply chain has at least two acceptable sources for each critical component.
Bill of materials
The detailed purchase list is in Phase 3 - Production BOM. It includes the field MVP components plus calibrated mechanical parts, a PCB/carrier board, waterproof connectors, solar sizing, and optional gateway connectivity.