Backyard Aquaponics
A place to discuss aquaponics

Can you show me more detail on your automatic feeder. I'm trying different mock-ups for mine and would love to see what you did.

I'll take some photo's when i'm next home (which is in a week or so) but here's a quick run down.

20mm PVC shaft with an auger in it.
Auger attached to servo motor that rotates auger.

at around the middle of the shaft, there is a PVC T, which feeds upwards to a hopper (which is basically a series of reducing couplings, taking the PVC up to 100mm down-pipe. There is then a screw cap on the top.
At the end of the shaft there is a elbow that directs feed downwards, and through the tank roof.

The whole thing is mounted on some angle iron, and screwed to the top of the tank.

Super difficult to describe!!! haha.

Anyway, basically an auger with a hopper above it, that shifts feed through some pvc into the tank. The hopper holds around 1kg at the moment, but we'll probably extend this.

How do you make the Rpi collect the information, I know with the arduino you wipe and upload the sketches, but how does it work with the rpi, do you go into raspbian or something and upload it all there, or is there a better way?

Yeah everything is stored on the Pi (and backed up to dropbox). I have a SQL server installed on the Pi which allows me to store and manipulate databases.

Then the webserver on the Pi is used to serve up the information.

This is all under raspbian as you say.

What do you mean by upload the sketches?

For some bizarre reason the arduino team decided to call code files/programs sketches, instead of files / programs

How strange! Well in any case, everything is recoded in permanant storage on the Pi

HEY nicbaz

Could you go into more details about your circuits? How is everything physically connected? Cameras, sensors, relays, what's stored 0n the card.... etc?

Maybe lay out a pseudo coded algorithm? Simple english statements maybe using line numbers, 10, 20, 30.....

Do you think the GPI0 will need to be expanded to another board like Beagle Bone or other types of processors?

Sorry for asking so many questions.

Just a 67 year "0ld Jar Head" with more questions than answers. Barely learning to crawl in the programming and controller world right now.

Keep asking because lots of us don't know this stuff.

Semper fi!

OO-RAH!

Well, this is fun isn't it!

Basically a Raspberry Pi B has a 26 pin header (2 rows of 13 pins).
Some of these pins are GPIO (General Purpose Input Output) pins, some are power, some have specialised functions, and some are GPIO with specialised functions. Here is a picture of it: http://www.raspberrypi-spy.co.uk/wp-con ... sion-2.png

So the three types of component I have connected to my Pi are relays, servo motors, and temperature probes (nothing fancy).

To connect a relay, basically you give the relay 5V and ground, and connect it to one of the GPIO pins. Then you can run a command on the pi that energises the pin (powers it on), which then switches the relay - easy .
Further to this, you can get relay modules that have several relay's on the one board.

To connect a servo motor, you again need to give the servo 5V and ground, as well as a GPIO pin. Then you basically send a signal over the GPIO pin that tells the servo motor to turn on. (The servo's have been modified to act as a motor, but still require the PWM signal https://learn.adafruit.com/modifying-se ... n/overview).

To connect a temp probe, you again have three connections, this time 3V3, ground and GPIO4 (pin 7), with a 4k7 resistor wired between GPIO4 and 3V3. https://www.cl.cam.ac.uk/projects/raspb ... mperature/

Now to the software...

I basically access and drive all the components through python, which is a reasonably simple programming language.
Basically, you import the GPIO library, then run the following command to do whatever you want.

Here is a program to switch a relay on and off:



which is called like this: sudo python /home/pi/Automation/gpio_out.py 22 1

which powers on GPIO22

and the following command turns it off: sudo python /home/pi/Automation/gpio_out.py 22 0

Regarding a BeagleBoard, my understanding that this is an alternative to the Raspberry Pi, rather than an expansion.
Think of the Raspberry Pi like a little computer, which it is.

If you run out of pins on a Raspberry Pi you can buy expansion boards that give you more GPIO pins.

Anything else I can help with, or anything I missed?

Hi nicbaz,

I've got some plans to employ a RPi or two when I get back to my system (I'm away for a protracted period, now)...

With your feed amounts, instead of using a plethora of "if" statements, I'd use a function like:
feed_multiplier = tempTank * 0.05 + addSomeIfYouLike;

Do you have a battery module in the RPi? I've seen some conjecture how long they actually last?

What components are you using on your web pages for the charts? (Freeware or licenced?)

Sounds good, lots of fun to implement!

I know, it would be better that way, but this is clear and allows for easy changes on the fly.
Unfortunately optimal feeding rate does not seem to be linear, so it would not be a simple y = mx + c equation to determine the feed rate (though the implementation above is linear).

Nope, no battery module, it gets the time from its internet connection.

The charts are freeware from google. https://developers.google.com/chart/int ... cs/gallery

I've been trying hard not to get into audrino or Pi since it's down the list of prioritised hobbies.
Getting tempted to knock it up a few places on my list now...

Fish work out how to press a lever within a few hours, so if you make the feeder feed only when there's demand, it allows for their fussy habits. it's still easy enough to keep the control you have, you just add an LED to let them know feed is available, and turn it off when they have had their ration for the day.