Tidmarsh Sensor Node

The Tidmarsh sensor node is a low-power wireless sensing platform that we have developed primarily for the Tidmarsh project.  It  contains an 8-bit microcontroller, 802.15.4 wireless, and a basic set of environmental sensors.  It is designed to run for several years from non-rechargeable batteries, reporting sensor data several times per minute.  For sensors with higher power requirements, the sensor node also contains a solar battery charger that can be attached to an external panel.
The sensor node also has I/O capability for attaching additional sensors and devices.

Hardware Specifications

CPU: ATxmega128A4U

  • 8/16-bit AVR core
  • 128K program memory
  • 8K RAM
  • Real-time clock
  • 12-bit A/D

Wireless: AT86RF231

  • 802.15.4 PHY/MAC
  • +3 dBm transmit
  • -101 dBm receiver sensitivity
  • omnidirectional on-board inverted-F 2.4GHz antenna
  • external antenna via U.FL connector

Environmental Protection

  • 3x3x2 inch watertight enclosure (IP-65 rated)
    • gray ABS, stainless screws
  • IP-67 filter membrane for RH sensor
  • Gore-Tex membrane for barometer
  • water-resistant circular connectors for external sensors


  • 3xAA cells, either alkaline or nickel-metal
  • alternatively, 3.7V lithium polymer cell via JST connector
  • maximum power point tracking (MPPT) solar charge controller (LT3652)
  • 2.2V system voltage
  • optional 1.8V/3.3V power domains for audio codec


  • Analog Devices ADXL362 micropower accelerometer
  • Bosch Sensortec BMP180 barometric pressure sensor
  • Sensirion SHT21 high-resolution temperature/humidity sensor
  • Intersil ISL29023 high dynamic range ambient light sensor


  • Aux 1 connector (4-pin .100 Molex KK connector)
    • 3-4.5V battery voltage
    • 2 A/D capable GPIO pins
  • Aux 2 connector (4-pin .100 Molex KK connector)
    • 3 A/D capable GPIO pins
  • Solar/Aux Power (2-pin .100 Molex KK connector)
    • 3.5V to 15V (overvoltage protected) input for solar panel or other charging source
    • This is an optional connection; only required for repeater nodes and audio nodes
  • Serial (6-pin .100 Molex KK connector)
    • I2C sensor bus
      • requires population of jumpers (disables FTDI compatibility)
    • asynchronous serial
      • compatible with FTDI header pinout
    • configurable power pin, options:
      • sensor node provides 3.3V via linear regulator; serial I/O is 3.3V
      • sensor node provides 2.2V via main switching regulator; serial I/O is 2.2V
      • power pin is input; external device supplies serial reference voltage between 1.8 and 5.5V
  • Mic
    • optional differential microphone input for audio codec; 3.3V biased for electret capsules
  • PDI programming interface
    • Program/Debug interface connector for main MCU

Audio Codec

  • VS1063 audio codec
  • MP3 or Ogg VBR encoding
  • integrated microphone preamplifier
  • programmable DSP