Architecture

Our entire system consists of three components - an embedded system, a webserver, and a webclient.

The embedded system runs on an ESP8266 WiFi module using micropython. The system connects to a WiFi network and a MQTT broker defined in the code, and subscribes and publishes to various topics, as defined bellow, to communicate with the webserver.

The webserver runs on Node.js and acts as a handler to interface between the webclient and embedded device. It communicates with the embedded device via MQTT and handles HTTP requests received from the webclient. The responsibilities of the webserver include:

• Storing:
  • Profiles
  • Sensor data
  • Device state
• Handling:
  • From device:
    • Initialisation request
    • Sensor data
  • From webclient:
    • Request for profiles
    • Creating new profiles
    • Turning device on/off
    • Current sensor data
    • Setting profile for the device

The webclient utilises the d3.js framework and AJAX to request and visualise the sensor data form the webserver in real time. Other services on the webclient include turning the device on/off, requesting the webserver to change the device profile, and create new profiles.

JSON

embedded to server - topic esys/icarus/status

{
    time: "str"
    temp: float
    hum: float
    plant: "str"
}

server to embedded - topic esys/icarus/params

{
    time: "str"
    temp: float
    hum: float
    plant: "str"
}

server to embedded toggle on/off - topic 'esys/icarus/power'

{
    power: int
}

Note: sensor should get start time when it initializes and track its own time

embedded to server alarm - topic esys/icarus/alarm

{
    alarm: "str"    # Error msg
}

Screen

screen /dev/tty* 115200

Uploading

ampy --port /dev/tty* put main.py

I2C API

writeto(bus_addr,data)
 - Opens write comm with slave at bus_addr, send each byte in data

readfrom(bus_addr,n)
 - Opens read comm with slave at bus_addr, read n bytes
 - Returns byte_array of n bytes

writeto_mem(bus_addr,reg_addr,data)
 - Opens write comm with slave at bus_addr, send reg_addr, send each byte in data

readfrom_mem(bus_addr,reg_addr,n)
 - Opens write comm with slave at bus_addr, send reg_addr, switch to read mode, read n bytes
 - Returns byte_array of n bytes

MQTT

• MQTT documentation http://docs.oasis-open.org/mqtt/mqtt/v3.1.1/errata01/os/mqtt-v3.1.1-errata01-os-complete.html

• MQTT micropython https://github.com/micropython/micropython-lib/tree/master/umqtt.simple

client = MQTTClient(CLIENT_ID,BROKER_ADDRESS)
client.connect()

client.publish(TOPIC,bytes(data,'utf-8'))

Sensors

• Humidity datasheet http://akizukidenshi.com/download/ds/aosong/AM2302.pdf micropython https://adafruit-micropython.readthedocs.io/en/latest/docs/esp8266/tutorial/dht.html

• Temperature datasheet http://www.ti.com/lit/ds/symlink/tmp007.pdf

ESP8266

• MicroPython https://docs.micropython.org/en/latest/esp8266/esp8266/quickref.html
• Pins https://learn.adafruit.com/adafruit-feather-huzzah-esp8266/pinouts
• Documentation https://cdn-learn.adafruit.com/downloads/pdf/adafruit-feather-huzzah-esp8266.pdf
• https://learn.adafruit.com/adafruit-feather-huzzah-esp8266?view=all