# Technical Specifications

Pebble is a battery-powered, cellular-based, multi-sensor development board designed by IoTeX and Nordic Semiconductor (opens new window), combining tamper-proof hardware and tamper-proof software to generate verifiable data.

Pebble is equipped with high-quality GPS, climate, motion, and light sensors. Data can be easily streamed in real-time to an MQTT endpoint for use in Cloud or blockchain-based applications.

Pebble utilizes a secure element (nRF9160) to cryptographically sign all data, providing unparalleled verifiability and traceability for asset tracking, supply chain, and other applications.

# Processor

Pebble is powered by a 64 MHz Arm® Cortex®-M33, 1 MB Flash and 256 KB RAM, with automated power and clock management, Arm TrustZone, and Arm CryptoCell 310

# Integrated Sensors

Pebble combines an environmental sensor (temperature, relative humidity, barometric pressure, altitude, and volatile organic compounds - VOCs), a motion sensor (3-axis gyroscope, 3-axis accelerometer), and an ambient light sensor. It's also equipped with cellular network connectivity and integrated GPS supporting precise, long range tracking of asset data using established cellular infrastructure.

Sensor Details
Environmental Sensor BME680 (opens new window)
  • Relative humidity
  • Barometric pressure
  • Ambient temperature
  • Air quality (VOC)
  • Motion Sensor ICM-42605 (opens new window)
  • 3-axis gyroscope
  • 3-axis accelerometer
  • External GPS TD1030 (opens new window)
  • Position accuracy: 3m
  • Speed accuracy: 0.1 m/s
  • Data frequency: 1 hz to 10 Hz
  • Ambient Light Sensor AMS TSL2572 (opens new window)
  • 45,000,000:1 Dynamic Range
  • Operation to 60,000 lux in Sunlight
  • Very High Sensitivity
  • Package UV Rejection Filter
  • Buzzer Mallory Sonalert AST7525MATRQ (opens new window)
  • Frequency: 2700 Hz
  • Sound Pressure Level (dB/min): 85 at 10cm
  • # Network Connectivity

    Pebble includes a Multimode LTE-M/NB-IoT modem for cellular communication. To have your Pebble connected to the Internet you will need an IoT-enabled** SIM card that supports either NB-IoT or LTE standards.

    # Data format

    JavaScript Object Notation (JSON) is utilized to represent the sensor data collected by a Pebble as well as the corresponding ECDSA digital signature. Pebble utilizes ECDSA over the elliptic curve sepc256r1 to sign the collected sensor data (i.e., the message field in the Pebble data format)

    Supported data types include Number, String and Array defined as follows:

    Data Type Data Size Data Range
    Array 16-bit -32768 ~ +32768
    Number 64-bit -1.79E+308 ~ +1.79E+308
    String null-terminated string

    An example of a JSON object containing a data point collected by the Pebble is shown below, it consists of a sensor data object named "message", and a digital signature data object named "signature":

    	message: {
    		SNR: 2,
    		VBAT: 4.0750732421875,
    		latitude: 3050.69225,
    		longitude: 11448.65815,
    		gas\_resistance: 1166811,
    		temperature: 36.23188400268555,
    		pressure: 1003.82000732421885,
    		humidity: 55.755001068115234,
    		gyroscope: [-12, 11, 14],
    		accelerometer: [-711, -231, 8260],
    		timestamp: 3443547577,
        random: "3767398368",
        rsa_n: "0xa709e2f84ac0e21eb0caa018cf7f697...8f628698f0c7b420c4b7",
        rsa_e: "0x010001"
    	signature:  {
    		r: "D7797968EAA3FFE5F8057C9D97F707A4A96CBFC250115FE6293EBA5E90327174",
    		s: "643A8CB823110376A5D30201463CF69CDF8CBF1C050EB85B023CABFB589C3222"

    The message object includes the following sensor data:

    Sensor Data Data Type Description
    SNR Number Signal-to-noise ratio of NB-IoT/LET-M
    VBAT Number Votage of battery
    latitude Number gps latitude
    longitude Number gps longitude
    gas_resistance Number Air quality
    temperature Number Environmental temperature
    pressure Number Air pressure
    humidity Number Environmental humidity
    gyroscope Array Angular velocity around the X-axis, Y-axis and Z-axis
    accelerometer Array Acceleration along the X-axis, Y-axis and Z-axis
    timestamp String Timestamp of sensor data sampling

    The signature data object contains the following signature data:

    Digital Signature Data Type Description
    r Number r value of an ECDSA signature
    s Number s value of an ECDSA signature

    # Onboard RGB Led

    Pebble includes an RGB led to show the status of the Pebble, the table below shows all the possible led states and the respective meaning:

    LED Color (Blink Rate) GPS Signal Charging NB-IoT/LTE Connection Flashing the Firmware
    Blue (fast)
    Blue (slow)
    Red (steady) +
    Purple (fast)
    Red (steady) +
    Purple (slow)
    Cyan (fast)
    Cyan (slow)
    Red (steady) +
    White (fast)
    Red (steady) +
    White (slow)
    Red (fast)

    Note that the led will blink at least twice in 1 second when in fast mode, and once in 5 seconds when in slow mode.

    # 2D Drawing

    Download DXF | PDF