Technical Specification – Smart Sensor Node SSN-01
Deliverable ExampleQuick Overview
| Parameter | Specification |
|---|---|
| Dimensions (L×W×H) | 42.0 × 42.0 × 12.0 mm (housing) |
| Weight | ≤ 18 g (incl. battery) |
| Battery | 1× CR2477, 3,0 V (typ. 1000 mAh) – replaceable |
| Communication | Bluetooth Low Energy 5.2 (2,4 GHz) + NFC for provisioning |
| Enclosure | IP67 (target: dust and water protected) |
| Measurement Accuracy | Temperature ±0,2 °C (0–60 °C), Humidity ±2 %RH (20–80 %RH) |
| Operating Temperature | -20 °C til +60 °C |
This document is a work example of pedagogical technical documentation that can be shared with a manufacturer when scaling from prototype to production.
Contents
- 1. System Overview
- 2. Key Specifications
- 3. Functional Requirements
- 4. Technical Requirements
- 5. Performance Requirements
- 6. Electrical Specifications
- 7. Mechanics and Drawings
- 8. Standards and Certifications
- 9. Manufacturing and Test (EOL)
- 10. Appendices
1. System Overview
Smart Sensor Node SSN-01 is a battery-powered sensor node for monitoring environmental data (temperature/humidity) and simple event detection (motion/tilt – optional). Data is transmitted wirelessly via BLE to a mobile app or gateway.
System Components:
- Sensor node (this specification)
- Mobile app for provisioning (iOS/Android) – reference interface
- Gateway / receiver (optional) – forwarding to cloud/backend
2. Key Specifications (overview table)
| Parameter | Specification |
|---|---|
| Dimensions (L×W×H) | 42.0 × 42.0 × 12.0 mm (housing) |
| Weight | ≤ 18 g (incl. battery) |
| Battery | 1× CR2477, 3,0 V (typ. 1000 mAh) – replaceable |
| Communication | Bluetooth Low Energy 5.2 (2,4 GHz) + NFC for provisioning |
| Enclosure | IP67 (target: dust and water protected) |
| Measurement Accuracy | Temperature ±0,2 °C (0–60 °C), Humidity ±2 %RH (20–80 %RH) |
| Operating Temperature | -20 °C til +60 °C |
3. Functional Requirements
The requirements below describe functionality from the user's perspective. For production and QA, these are translated into testable acceptance criteria.
| ID | Requirement | Acceptance Criterion |
|---|---|---|
| FR-01 | Measure temperature and relative humidity with configurable interval. | Interval 1–60 min can be set via app. Measurement is logged and can be read out. |
| FR-02 | Transmit latest measurement values wirelessly to mobile/gateway. | BLE advertising or GATT-read updated within 5 sec after measurement. |
| FR-03 | Secure provisioning/pairing. | Device can be locked to user/gateway. All configuration requires authentication. |
| FR-04 | Local buffer on lost connection. | At least 24 hours of measurement data stored locally and sent when connection is restored. |
| FR-05 | Over-the-air firmware update (OTA). | OTA can be performed without physical access. Update verified with signature. |
| FR-06 | Status indication for user/installer. | LED provides clear indication for: on, provisioning, error, low battery. |
4. Technical Requirements
Technical requirements ensure that the design can be manufactured reliably and tested on-line (EOL).
| ID | Parameter | Requirement | Verification |
|---|---|---|---|
| TR-01 | Supply Voltage | 2,0–3,6 V | Measurement |
| TR-02 | Sleep Current | ≤ 5 µA @ 3,0 V (typisk) | Measurement |
| TR-03 | PCB | 4-lags FR-4, Tg ≥ 150 °C, tykkelse 1,0 mm | Inspection / documentation |
| TR-04 | ESD-beskyttelse | IEC 61000-4-2: ±8 kV kontakt, ±15 kV luft (mål) | Test |
| TR-05 | Antenna | Integrated 2.4 GHz PCB antenna or chip antenna | RF-test |
| TR-06 | Programming / test | SWD pads + test points accessible from bottom side | Inspection |
5. Performance Requirements
Performance requirements describe the expected level in operation. They serve as the basis for battery calculations, RF testing and field validation.
| ID | Area | Requirement | Verification |
|---|---|---|---|
| PR-01 | Battery Life | ≥ 18 måneder ved 10 min måleintervall, 25 °C | Analysis + field measurement |
| PR-02 | Radio Range | ≥ 20 m indoors (typical), ≥ 50 m line of sight | Test |
| PR-03 | Startup Time | < 3 s from battery insertion to advertising starts | Test |
| PR-04 | Data Loss Tolerance | 0 critical data loss in normal operation; buffer on interruption | Test |
6. Electrical Specifications
This section describes electrical behaviour relevant to component selection, EMC, test setup and troubleshooting.
| Parameter | Specification |
|---|---|
| Battery Type | CR2477 Li-MnO₂ (coin cell) |
| Nominal Voltage | 3,0 V |
| Capacity (typ.) | 1000 mAh (depends on supplier) |
| Max Peak Current | ≤ 25 mA during radio TX (brief) |
| Charging Circuit | Not applicable (replaceable battery) |
| Microcontroller | ARM Cortex-M0+/M4F class (selectable per BOM) |
| Sensor Interface | I²C, 400 kHz (temperature/humidity) |
| Test/programmering | SWD + UART testpad (opsjon) |
Recommended Test Setup (EOL):
- Current measurement in sleep (µA) and during TX peak (mA) at 3.0 V.
- BLE functional test (advertising + GATT) in shielded area or defined RF setup.
- Plausibility check of sensor: temperature and humidity within defined range.
7. Mechanics and Drawings
For manufacturing, unambiguous dimensions, tolerances and mounting points are essential. Below is a simplified drawing showing the principle and key dimensions. In a real project, STEP/DXF and detailed 2D drawings are attached as appendices.
8. Standards and Certifications
Mapping standards early reduces the risk of redesign and delays. The list below is typical for BLE sensors, but must be adapted to market (EU/US) and end product.
CE / EU:
- RED 2014/53/EU (radio equipment)
- RoHS 2011/65/EU + (EU) 2015/863
- REACH (EC) No 1907/2006
- WEEE 2012/19/EU (labelling/return scheme)
Harmonised Standards (BLE 2.4 GHz):
- EN 300 328 (2,4 GHz radio)
- EN 301 489-1 og EN 301 489-17 (EMC)
- EN 62368-1 (safety – IT/AV equipment)
- EN 62479 (RF exposure – low power)
USA:
- FCC Part 15 (Subpart C)
Battery and Transport:
- UN 38.3 for lithium batteries
- Labelling and packaging in logistics
9. Manufacturing and Test (EOL)
EOL (End-of-Line) test plan describes which checks are run on each unit. A clear test flow gives higher yield and easier troubleshooting.
Proposed EOL Test Flow:
- Visual inspection (PCB, solder joints, component placement).
- Firmware programming + unique keys/ID (MAC/serial).
- RF check (BLE advertising, TX/RX, RSSI).
- Sensor check (plausibility/calibration control).
- Current consumption test (sleep + peak).
- Functional test (LED, button, NFC if mounted).
- Sealing test (if IP67) – sampling plan defined in agreement.
- Packing (ESD bag, label with QR/serial, batch number).
Traceability
Each unit shall have a unique serial/QR code linked to firmware version, batch and test result.
Packing
ESD-protected bag. For IP requirements: include gasket inspection and screw torque check (if applicable).
