Accessible IoT Plant

There are quite a few types of self-watering plants but this one adds IoT services and accessibility into the mix. I have also kept the use to 3V rather than 5V to make it easier/cheaper for the classroom.

• Microbit V2 or V1
• Microbit Shield (any will do)
• Ultrasonic Sensor HC-SR04
• ESP8266
• 180 degree Servo SG90
• Pipet or straw
• 2 x Wooden skewers
• 1 x Tooth pick (optional)
• 3 small elastic bands
• 2 x nails or screws
• Electrical Tape
• Scissors or clippers
• Cup
• Plant
• 11 x female to female jumper wires (dupont)

• Connect your Microbit to the shield
• Take 2 jumper wires, strip off the ends of one side each onto the nails with electrical tape.
• Connect the wires to a 3V positive pin and pin 0 of the microbit
• Then program the Microbit to read the moisture of the plant using Makecode

• Wire the ESP8266 to the shield using jumper wires
• Make a copy of the wiring diagram in TinkerCAD circuits here
• Search Makecode extensions for "ESP8266" and add the blocks
• Follow the Makecode instructions above to connect the Microbot to the internet
• Pin 16 for the RX and Pin 12 for the TX
• Connect your sensor readings to ThingSpeak by creating a new Channel making sure you have the API keys
• Follow the extra Makecode instructions
• Make sure your sensors are recording data

• We are going to make a movement sensor for audio cues
• Wire the Ultrasonic Sensor to the Microbit shield using the diagram
• Trig to Pin 1 and Echo to Pin 8
• Add the Sonar Extention to Makecode
• Follow the Makecode instructions

• Add the self-watering mechanism using a servo
• Use elastic bands (or glue if you prefer) to fix the two long wooden skewers to the servo
• Use an optional toothpick to secure the elastic bands on the short side.
• Cut a hole in the pipet (or use a straw with a bend) to act as a reservoir for water
• Attach the pipet to a servo arm with elastic (or glue)
• Add the Servo extension to Makecode
• Follow the Makecode instructions
• Attach the servo to Pin 2
• Attach the mechanism to the plant or water cup. Whichever is easiest for your cup of water
• Secure the legs of the mechanism with an elastic band around the cup or plant.
• Experiment with the servo arm angles
• YOURS WILL LIKELY BE DIFFERENT ANGLES TO MINE

• Your measurements may be very different from mine
• I have experienced ranges from 700-1000 for moisture levels using different shields and materials.
• The temperature may also need to be tweaked by adding simple additions to the Makecode to add or take away degrees. As above.
• Use the Thingspeak app Thingview to make a public or private page for your plant

Rather than use a pipet or straw improve the design using TinkerCAD 3D design.

Ideas for improvements:

• Better watering mechanism
• Using the data to predict the watering needs in a calendar
• Adding notifications from Thingspeak into Amazon Alexa using IFTTT. Link here
• Build an all in one 3D printed plant pot with water reservoir and holders for the Microbit and Sensors
• Send tweets about your plants conditions on its own account. Link here

You can use the "potato" battery to simulate the servo responses using the TinkerCAD circuits page if you do not have any kit on you.