My colleague @dansku and I have been throwing ideas around for a smart houseplant monitor on and off for a few weeks, and we’ve gradually collected a few parts to prototype it. I thought why not document our progress on the forums; hopefully some of you will be inspired to join the project and build something too, if not you can always follow along and any ideas/feedback are welcome!
I’ve got a few things in mind I’d like to achieve:
- Monitor soil moisture
- Monitor temperature & humidity
- Automatic watering for when you’re away
- Alerts (maybe via Twilio)
- Physically small and tidy - the goal is to use a Pi Zero W, eventually with a custom HAT for compactness
- Low cost, around $30 - I’d like people to be able to have a few units in the house (and take advantage of the fleet management part of balenaCloud!) without spending a fortune
- Reliability - it needs to be robust and last well, the monitor shouldn’t need more maintenance than the plant!
- Visual status indicator - an 8x8 LED matrix, or RGB LED if we run out of budget
- Pretty charts with Grafana
How we actually satisfy the above is yet to be determined, but we’ve started getting hardware together. Note: Please don’t take this list as a required list of components as things may change as we develop the project, it’s more for documentation and prototyping purposes. Most of these links are from AliExpress for price reasons.
- Soil moisture sensor - capacitative type ($1.98)
- Temperature sensor - DS18S20 1-wire probe ($2.38) Maybe a DHT11 temp/humidity sensor would be good instead ($0.63)
- Raspberry Pi Zero W ($10.00)
- Water pump - 6V peristaltic dosing pump ($7.88)
- Relay board for controlling pump - Grove relay board ($2.90)
- LED matrix - 8x8 with i2c backpack ($4.95)
- i2c ADC required for soil sensor ($1.75)
- Float switch to monitor water reservoir ($1.51)
- 5V 3A PSU - testing will show if this is enough ($3.74)
I think that’s all the hardware we’ll need, aside from a 3D printed case and maybe some cable. That brings us to $35.34. Some items, particularly the LED matrix can be had cheaper if you buy a 3 pack so this isn’t too far off the goal.
I’ll start putting stuff together and see what happens!