plant peter or plantage peter was my ohshititotallyforgottobuysomething gift to my mother. I started to build him on the 18th of December and finished on the 22th.

Plant peter sits in your plant with his moisture sensing feet and tells you when you need to water your plants. He has three facial expressions sad,middle(meh) and happy

This project is perfect as a one-day gift if you have access to a 3D printer and are comfortable with electronics. If you dont have access to a 3d printer you can check out 3d hubs.

If beer is more of your thing check out plant peter brother bir bot!

Step 1: 3D Printed Parts

The parts can be found here.

The body does need support material and should be printed face up.

Note: my prints had alot of problems because i printed them fast, but if you print at normal speed with some sort of cooling overhangs shouldn't be a problem.

Step 2: Electrical Components

You will need:

1x arduino nano
1x soil sensor
1x led matrix with max7219 controller
1x power switch
1x battery holder and batteries (4xAA/AAA)

Step 3: Assembly

Now its time to wire stuff to your arduino. We will start by wiring up the led matrix, Use the picture above and the pin guide below. Its important that the right arduino pin is connected to the right matrix pin.

pin 7 - DataIn
pin 5 - CLK
pin 6 - LOAD (or CS)

The soil sensor should be connected to analog pin 1 of the arduino. If your soil sensor has an external board (like mine) use the analog out, not the digital.

Make sure to also connect the batteries to the arduino vin and wire in a power switch.

By now you should have both the soil sensor and the led matrix connected to your arduino. Its now time to upload the sketch to your arduino. You can find the sketch at the bottom of this step. You will need the led control library to upload this sketch, it can be found under arduino ides library manager.

Upload the sketch and try out your new gadget! If you feel that your readings from the sensor is ok, you can skip the calibration step.

Calibration:

To calibrate your plant peter you need to connect the arduino to your computer again. Open up the serial monitor, you should see readings from the sensor every second. high means dry, low means wet.

Get three different plants/soil samples. One with a good amount of water, one that is OK and one that need to be watered. Test plant peter in the different soils and write down the results from the serial monitor.

Now you need to change the values in the arduino sketch you should see three diffrent if statments with sensr in them. They look like this:

if(sensr <= 500) - this is the smiley
if(sensr >= 500 && sensr <= 700) - this is the straight line
if(sensr >= 700) - this is the frown

Change the values to the values you got from your reading. If something goes wrong you can always download the original sketch again.

Almost done...

Now that your plant peter works as it should its time to fit the components in the 3d printed enclosure. Jam the matrix into the enclosure with the pins pointing toward the body and secure it with hotglue. Glue in the moisture sensor in holder at the bottom of the print.

Glue the battery holder to the back of the lid and screw in the switch. Guide the cable from the moisture sensor trough the second hole in the lid and glue the lid shut.

Thats it! your very own plant peter is done! if you are wondering over anything, comment below!