FabLab Irrigation System
Design
C++ for a Microprocessor that includes an embedded http server.
The http server displays controls for N zones, where each zone has:
- turn on time
- turn on duration
Valve1 \
Valve2 --- Microprocessor <==> Web Interface
ValveN /
Web server methods
| Endpoint | Purpose |
|---|---|
| /getData | returns json |
| /updateData | gets updated json |
Core Logic
- start with our json object.
- we get new data (temp/humidit/y/relay status)
- update the json object
- serialize ==> json
- return json to html
State Problem
When the microcontroller loses power, we lose state. We therefore need to persist settings to disk.
- Settings are read from disk on startup
- Settings are saved each time a user changes settings in the web ui
- Settings are kept in memory and we check against them
Psuedo code:
Startup:
- read json to doc obj
- init wifi
- init http server
/getData
- serialize doc obj to Json
- return Json to caller
- no logic
/updateData
- take incoming Json and save it to disk
- arduinoJson magically serializes incoming request to our doc object for free
- no logic
Loop (no disk i/o):
- examine current state of in memory doc object and take action
Data format
{
"data": {
"currentTime": "Tuesday, June 23 2020 11:54:16",
"temperature": "29.90",
"humidity": "51.00",
"override": 0,
"ssid": "myssid",
"pass": "my password"
},
"relays": [
{
"name": "Fruit Tree",
"pin": 25,
"isRunning": 1,
"isEnabled": 0,
"times": [
{
"startTime": "03:00",
"duration": "0"
}
]
},
{
"name": "Vegie Garden",
"pin": 26,
"isRunning": 1,
"isEnabled": 0,
"status": 1,
"times": [
{
"startTime": "12:00",
"duration": "0"
},
{
"startTime": "12:30",
"duration": "0"
}
]
},
{
"name": "Cypress Hill",
"pin": 33,
"isRunning": 1,
"isEnabled": 0,
"status": 1,
"times": [
{
"startTime": "12:45",
"duration": "0"
},
{
"startTime": "10:00",
"duration": "0"
},
{
"startTime": "16:45",
"duration": "0"
}
]
}
]
}