Final Project - Plant feeder
For the final project I decided to continue with my half-term project - ‘Plant Feeder’. Originally I intended to make a guitar pedal with a compressor effect for my partner (he’s an avid guitar player), but decided it against, as I didn’t have enough knowledge in using Op-Amps (operational amplifiers) and saw the struggles of the people who decided to build some sort of sound amplifier circuits. In theory it looked extremely simple, but weighting knowledge and timescale we have (sourcing materials and waiting for shipments, etc) this was a better bet, as I wanted to fully realise my plant feeder.
First, I established some of the areas that I want to improve in my project, such as: fixing the bugs in the code, adding temperature and humidity sensor, full-proofing the pump, making a user interface with a menu, making the top plate of my enclosure to accommodate the screen, design a manual, etc.
Firstly, I decided to design the PCB for easy plug-n-play screen installation (I wanted to be able to take it out if I needed it), buttons and extended 5V and Ground connections, for other parts (temperature sensor, moisture sensor, and anything else). I wanted the PCB to have all the connections, resistors and interconnections done on the board, so I would only have to plug the jumper cables and it should work. A self contained ‘module’, if you will. I designed the board just big enough to fit on top of my current enclosure. I/Os include:
3 buttons - all have common ground through 10k Ohm resistors and 3 pins for jumper cables.
Screen headers - all the power needed is wired on the board (resistors are present as needed, mostly for screen contrast which is fixed by a 1k resistor).
5V VCC and common GROUND - the board is powered by 5V and GND from the Arduino and extends them with extra 4 VCC and GND pins for plugging other sensors and a pump.
PNP transistor as switch - for controlling the pump with one pin from Arduino. Easy peasy (not so much then, figuring it out late at night).
All in all I’ve learned quite a bit of having to design this for my own use (I tried before - wasted 3 boards…) and it was extremely satisfying to see it work exactly how I intended it to.
A side note: I wasted a lot of the time trying to design my own boost board as I was adamant to have solar energy powering my ‘Plant feeder’. I failed, of course, as I didn’t leave enough time for that. But I did manage to grasp the concept of storing the energy in a coil, collapsing the magnetic field and boosting the voltage. Unfortunately I didn’t document this part (I did it while helping make some electro magnets that became a part of my not-so-working boost converter) as I was too frustrated with it that I ripped it apart and never looked back. What a fool… But I did have fun ripping apart an old television to get an inductor.
After making sure my board is working, I began programming a user interface for my ‘Plant Feeder’. Requirements: simple main info screen, with stats; two options in the second part - changing the frequency of watering and amount of water to use. Again, I ran into issues with implementing sleep (Idle) timer, as it relied on millis() function, which, after few seconds of running, would return exo-orbital values. I tried using modulo but that didn’t help either. In the end I did manage to make it run somewhat stable through use of some variables.
So far so good right? Not so fast. Due to addition of extra of sensors the amount of cables that the poor enclosure had to accommodate grew as well, with an addition of the screen and buttons. The wire-o-mess at the end of plugging everything together proved impossible to fit everything neatly, leaving the dandy PCB I made (as nice as it looked) dangling outside. A bit like a plant. (Silence for a bad pun should happen right about now).
With helpful feedback from my peers and lecturer, I set out to design a new enclosure. I spoken to my flatmate (thank you, Ieva) who gave me an idea using watering pot as an enclosure. It looked great in practice, but I would be just buying a ready made one and cannibalising it to fit my electronics inside of it (perhaps I’ll use it for the future ‘outdoors’ Plant-feeder). Instead I designed my own minimalistic pot in SketchUp Make and 3D printed it.
















