i am big into Arduino hacking these days, and I wanted, like so many others, to write my own aquarium controller.
Lighting is obviously a big part of it, and I was looking to control the Fluval 2.0 LED ramp.
What first got me into this idea is the fact that the LED fixture can be controlled by a (crappy) touch-sensitive button, OR
by a wifi gizmo that plugs between the wall wart and the fixture.
The Led 2.0 is a 2-channel light. It has white and blue. When you press the touch sensitive button on the fixture, it goes from WHITE, BLUE, OFF. Touch-holding the button will slowly dim, then slowly brigthen the LEDs.
Apparently, when you plug the wifi controller, the light needs to be in its OFF state for the controller to work.
The connector from from the wall wart to the fixture is some sort of 4-pin DIN connector. With a multimeter, I have easily identified +24V and 0V.
The two other pins are more complicated to figure out. Because the Wifi gizmo plugs directly into the wiring that has those 4 pins, I figured they could be PWM signal.
Without an oscilloscope, I used an Arduino to peek at the voltage signal coming from the 5V lines. Turns out the 5v turns on-and-off at not-so-steady rate that can range anywhere from 60 to 150 Hz, averaging at a pretty constant 87 hz over consecutive 10 second intervals of measurement.
Voltage on-off cycles typicall range from 6-8 milliseconds at 5v followed by 6-8 milliseconds at 0v, about 46% duty cycle. But a typical PWM should be at around 1000 Hz.
I don't have an oscilloscope here, but I don't think it's PWM. The wave is just too darned inconsistent and nowhere near the frequency of a typical PWM.
Maybe some sort of square or sine wave, though the voltage drops go from 5V to 0V quite quickly.
Going back to the WIFI gizmo that sits between the wall wart and the fixture, I'm guessing it's a self-sustained microcontroller that talks to the iPhone application, downloads the settings, and then drives the lights from the 5v signals of the connector.
So what I want is basically to reproduce the control of the WIFI gizmo has over the light, but I want to control the light depending on conditions other than just a schedule.
And besides, reverse-engineering stuff is just so much fun.
Anyone has suggestions on where to go from here?
For reference: you can look at the 4-pin plug and the wifi gizmo thing here: