tech-specs.md

Tech Specs

Pebble is a battery-powered, cellular-based, multi-sensor development board designed by IoTeX and Nordic Semiconductor, 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.

CPU

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	Relative humidity Barometric pressure Ambient temperature Air quality (VOC)
Motion Sensor ICM-42605	3-axis gyroscope 3-axis accelerometer
External GPS TD1030	Position accuracy: 3m Speed accuracy: 0.1 m/s Data frequency: 1 hz to 10 Hz
Ambient Light Sensor AMS TSL2572	45,000,000:1 Dynamic Range Operation to 60,000 lux in Sunlight Very High Sensitivity Package UV Rejection Filter
Buzzer Mallory Sonalert AST7525MATRQ	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 _I_oT-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,
	  light: 1639.67767,
		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	Voltage of battery
latitude	Number	gps latitude
longitude	Number	gps longitude
gas_resistance	Number	Air quality (indoor)
temperature	Number	Environmental temperature
pressure	Number	Air pressure
humidity	Number	Environmental humidity
light	Number	Ambient Light
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
random	Number	A random number generated by the onboard random number generator
rsa_n	Number	Modulus of the RSA keys (only provided in specific applications where on-chain data encryption is involved)
rsa_e	Number	Public exponent of the RSA keys (only provided in specific applications where on-chain data encryption is involved)

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

{% file src="../../../.gitbook/assets/pebble-drawing (1).pdf" %}

{% file src="../../../.gitbook/assets/pebble-top-view.dxf" %}