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Hawk Concepts

It is helpful to understand key concepts around the Hawk. 

Hawk baseboard + IO cards


The Hawk unit itself we refer to as the 'baseboard'/'motherboard'/'host'. Key components of the baseboard are:

  • Cellular or satellite modem to allow for data upload
  • External power input + back up battery
  • Microcontroller + Memory to store and process records
  • I/O screw in terminals
    • Vin, GND and Digital Input 1 are for the Hawk
    • I/O 1 → I/O 8 are used by the plug in card to connect sensors and other I/Os

This format allows for flexibility in I/O selection, and which sensors we can connect to. 

I/O Cards

Each application may require various sensor types and input combinations - i.e. I²C for a temp sensor, SDI-12 for soil moisture, and a digital input for a pulse count. Another application may require 3 x Digital Inputs and RS485. 

Currently, there are 2 available card types, Ag-Tech1 and RS1, the available interfaces can be seen here: Hawk Baseboard + Plug in Cards - Wiring+Pin Out

If you require a specific interface or combination of interfaces for an application - it is possible for Digital Matter to produce custom card types. Contact our support team to discuss.

Card + Baseboard Communication

The Hawk can request the card to perform actions, such as:

  • Sample the Analogue input, and return the value
  • Read from the SDI-12 probe and return the values
  • Turn on the 3V3, SW Ground or VBoost outputs

The data is returned to the Hawk by setting Hawk Digital Inputs, Analogue values and special data fields (like SDI-12 data field)

Cards can also raise events, such as a digital input change. The Hawk will receive this event and then can be configured to take immediate action (i.e. log and upload the event)


The Hawk's parameters are centred around the concept of a 'task'.

A task is a set of actions. A task can be scheduled (e.g. hourly) or run in response to an event (digital input change or analogue threshold).

Actions are shown below - they are either reading a sensor, or turning on an output. 

Tasks are configured with the below key intervals

  • Schedule Period - how often we perform the task
  • Logging Multiplier - Log every L times the task occurs
  • Upload Multiplier - Upload every U logs
  • GPS interval  - Get a GPS fix every G logs

This allows for options like:

  • Sampling a sensor frequently (say every 5 min) - to monitor it's value against a threshold and action accordingly, but only logging a record every 15 to reduce data usage and server load
  • Setting the GPS interval to 0 or a very large number, to get a fix infrequently or not at all if not required - increasing battery life
  • Sample and log a value every 10 min, but upload hourly

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