The Enviro Grow comes with 3 moisture sensors and 3 pumps. What is the simplest way to add more pumps to the Enviro Grow?
There are a ton of I2C ADC’s out there so it’s easy and well documented to add more moisture sensors. But I can’t find I2C devices that add more low current pump connectors. Wouldn’t it be cool if there was an I2C device with 4 more simple channels.
The best I can find are scetches of how to solder a MOSFET and some other components to some free GPIO pins in order to switch the low GPIO current to the full 1A VCC required to run a pump. But that’s too complex and frankly, too ugly to do with the very pretty well designed Enviro Grow.
Are there any options?
A motor controller should work, anything with a H Bridge should do the trick. Just make sure its Pico compatible. The pump is just a DC motor at its heart.
If your good with a soldering iron and get creative with how you wire it up, two of these should work.
Motor SHIM for Pico (pimoroni.com)
EDIT: There is also this,
DRV8830 DC Motor Driver Breakout (pimoroni.com)
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Thank you. That second item is almost exactly what I want. In theory. I2C connected and good looking.
But I have 10 additional pumps, so I need 10 of those. That would cost £108 plus £25 shipping plus import tax because I’m outside of GB. My budget is about £20 total. And if it wasn’t, the item only has 4 I2C addresses.
I’m trying to find something simpler and cheaper. When looking at the Enviro Grow PCB, the engine drivers are very simple: Super tiny MOSFET’s are switching the 3.3 volts using GPIO pins. Just on or off: No speed or direction, so no H-bridge required.
Everyone wants to toggle low current 3.3V devices on and off. So I assumed there would be many such I2C extensions, like 8-channel or 4-channel on-off ports. I’d only need to purchase 2 or 3 of them. Perhaps I’m mistaken, but hopefully I just can’t find what I am looking for because I don’t know the proper terminology.
Alternatively I can use some of the pico GPIO pins that are free, but most are in use. That’s why the Qw/ST I2C seems to be the cleanest. There are also simulated GPIO extension boards for I2C so I can use 16 pins, enough for 10 motors. I’d need some kind of easy solution to turn those pins into switches.
I see your point. Just don’t know what to search for? Might want to poke around in the Robotics section?
Thank you. That is indeed a good candidate. It drives one port per pin. I’ll add it to my shortlist. I’m not completely satisfied though. It’s rated 10 times the voltage than I need, meaning it’s unnecessarily bulky, especially to add 10 of them.
Here are some other things that are sort of but not exactly what I want:
If anything, I learned that technically it’s definitely possible. I wonder what those people on the Pimoroni pump reviews page saying “I use 7 pumps for my next project” use to drive the pumps. All the Enviro products come with picoblade 3 ports.
Also I wonder if I can abuse one of those logic level converters to toggle VCC using GPIO:
If they can handle the current its likely a good choice. You need to look at the schematic and see what’s what.
I’m getting closer to budget. Still way to bulky and powerful for 3.3V 1A pump motor but less complicated than gambling with level converters.
Physical relays are cheaper apparently but still overkill.
Be careful if you use relays! The back EMF pulse can damage things.
Me personally, I’ll take solid state over mechanical.
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