Firmware

The firmware contains all the instructions that the sensor node needs to take measurements of environmental data, control attached devices, and communicate with a web server. The following firmware files provide the essential functionality for the sensor node.

• [ main.c ] contains the main ''operating system'' for the sensor node. At a recurring interval, this program (i) ''wakes'' the board from sleep mode, (ii) takes measurements using the attached sensors, (iii) connects to the cellular network, (iv) sends sensor data to a web server, (v) updates device metadata and onboard parameters, (vi) triggers attached actuators, and (vii) puts the board back into sleep mode.

• [ data.c ] implements the sensor subroutine, metadata updater, trigger updater, and parameter updater.

• [ modem.c ] contains functions for connecting to the cellular network, and sending/receiving packets.

• [ updater.c ] implements parsers needed for the metadata, trigger, and parameter updater subroutines.

• [ ultrasonic.c ] contains routines for taking measurements using the Maxbotix depth sensor.

• [ decagon.c ] contains routines for taking measurements using the Decagon soil moisture probe.

• [ autosampler.c ] contains routines for taking measurements using the ISCO autosampler.

• [ valve.c ] contains routines for controlling an attached valve via an actuator.

Main loop

The sensor node's main routine (as implemented in main.c) is shown below: