EHX HOG Foot Controller... how does it work?

[3080]

Here is all my knowledge about the HOG foot controller.

http://www.ehx.com/products/hog-foot-controller





So... can someone explaine me, how this thing works? Any ideas, how it would be possible to get informations about it's output signal?

[theehman]

It uses a microcontroller.

[3080]

I see. Maybe some information about it's output? What does it do when a switch is pressed? It sends a variable voltage, or some impulses to the HOG?

[Jazznoise]

It's just a PIC with some commands you toggle through - the real bit to know is what the HOG can read as there'd be a number of ways to get the PIC to essentialy do the same thing. There's possibly redundant/unused variables the Hog Controlled can't do, too, so it'd be interesting to see it. But expect it to be Flowcode or some sort of C coding variant. So, yes, sequenced impulses 

But considering the cost of the HOG and its foot controller I'd be very impressed if someone was willing to risk losing all that data, and essentialy the functionality of the HOG, to see the script. And I wouldn't see EHX taking a return with solder burns.

[aquataur]

Since the controller is connected to the HOG unit via a standard guitar cord and thus only has one line to communicate besides ground, this can only convey either an analog voltage (meaning: six distinct levels for six footswitches), or a serial protocol.

The first is utterly possible, since they use a linear voltage for changing stuff on the expression pedal (they use the potentiometer of a simple volume pedal). A microcontroller can output analog voltages. This can easily be determined with an oscilloscope. Such a device cannot possibly harm any of the two units.

The second option is possible, too, since a microcontroller works in the digital domain. The µC is used to sample the footswitches, to de-bounce them and to save their state (I hiope) upon power-off. I am rather inclined to this option, because it would be utterly overkill to use a µC for the first option. But with respedt to component count, one never knows. Microcontrollers cost nothing today, and more and more people are capable of working with them rather than discrete electronics. But EHX?

However, looking at the innerds on the picture... a hefty price tag fur such a trivial appliance. If you consider that for a few dollars more you get a full-blown digital guitar effects processor in a sturdy housing (speak: digitech)...
The HOG itself is comparably cheap if you consider what´s inside of it.

addendum: just realize that it has to be digital. The foot controller is powered over the very same cable, so it has to be some sort of phantom power with a digital serial information riding on it.

Having programmed a lot of similar applications, I guess the code is fairly trivial. On the receiver side (HOG) there would be a similar circuit, maybe even bi-directional if they were fancy. One would need to sniff the transfer protocol with an oscilloscope, but reconstructing the code is not a beginner´s task, although the hardware entirely is. Certainly not worth the money they ask for, although this is, as I said, overpayed for a dumb box.

have fun,

-helmut