Zmota AMBI

It is a low-power smart Zigbee Pro node that has as main objetive to monitor the temperature and the humidity. It has the following features:


  • Based in low power, high-Performance 8 bit microcontroller  PIC18F26J11 (28 Pin QFN package, 64KB program memory, 3KB SRAM and up to 12MIPS).
  • Customizable firmware to implement different application roles. PIC18 architecture is optimized for C programming.
  • Free MPLAB© Integrated Development Environment
  • Free C compilers (CCS demo edition)
  • Single-Supply In-Circuit Serial Programming™ (ICSP™) and In-Circuit Debug (ICD). Connection without programming header, “Tag-Connect In-Circuit Cable No Legs” (Part Number: TC2030-MCP-NL) is used instead.


Onboard sensor to measure temperature and humidity (Sensirion SHT21).

  • Fully calibrated and linearized. Excellent long term stability.
  • Output signal in digital I2C format.
  • Humidity:
    • Range: 0-100%RH
    • Max resolution: 0.04 %RH
    • Typ. Accuracy: ±2.0%RH
    • Typ Response Time: 8s
  • Humidity:
    • Range: -40-125⁰C
    • Max resolution:0.01⁰C
    • Typ. Accuracy: ±0.3⁰C
    • Max Response Time: 30s
  • Low power consumption. 3×3 DFN type package

 Performance in the measurement of the temperature and humidity of complete system (this is inside enclosure for example) should be correlated in order to have real values.

External ports

2 lines input/output digital port (5V tolerant) for several uses:

  • Communication port (UART, SPI, I2C) to manage smart sensors or meters. For example, gas, electricity, water meters with digital output such as pulse or serial communication.
  •  Control line (level, PWM) to manage external devices.
  •  Completed external I2C port (SDA, SCL, GND and Vcc).
  •  Analogic input


It can be powered from any DC source from 2,5 V to 12 V. For example, 3V coin cell, 2 x 1,5 V alkaline batteries, NiMH rechargeable 3,6 V batteries, 5 V USB, etc. There are available two power inputs line: regulate (external power) and nonregulated (battery connection).

When powering the unit with more than 3,3 V the on-board voltage regulator must be used to reduce the voltage to 3.3V. The battery connection header is not regulated, therefore 3.3V max should be connected to it. If higher voltage is connected there is risk of damage.

Zmota AMBI  has been designed to be low power. Much power optimisation is done in firmware (see details). The measured current with a 3.7V external power (on board voltage regulator is used) is:

  • 10mA when system is awake.
  • 50uA when system is sleep, (RTC is running and ZigBee communication is operative).
  • 50mA (average value)  when ZigBee is transmitting.


2,4 GHz ZigBee Pro wireless standard protocol:

  •  Based in ETRX357 Telegesis module with Ember EM357 chipset with two different firmware options:
  • Mesh networking support with thousands of nodes in same network, support of mobile nodes, security and data encryption
  • ZigBee Manufacturer Specific Profile guaranteeing interoperability:
    • do not interfere with existing ZigBee Networks in a malicious way
    • can join a 3rd party ZigBee PRO network and use its routing capabilities
    • can allow 3rd party nodes to join into a network and use its routing capabilities
  • Different ZigBee profiles can be implemented just with firmware changes; for example, Zigbee Smart Energy when connected to meters.
  • Configuration as router, sleepy end device or mobile device.


Z-mota AMBI v.1.0 has has been licensed under the CERN OHL version 1.1.


  • Ángel Asensio (HOWLab)
  • Rubén Blasco (HOWLab)


Firmware versions

  • THSensor 1.4.
    • Description:
      • This firmware has been designed for the aemSystem, in order to monitor the temperature and humidity of a house with very low power consumption. Supports two operating modes:
        • Mode 0 (wait): The device is waiting to be configured.
        • Mode 1 (working): The device wakes up periodically to send the information of temperature and humidity. The rest of the time the device is in power down mode
    • Communication Protocol: This device is using the CCP protocol:
      • THSensorCCPSummary
    • License: GPL 3
    • Source code


Related projects & devices

Z-lita Dongle


Use Cases

 Ambient and Energy Monitoring System (aemSystem)

Pictures and videos