Fat Frog Controlled From Raspberry Pi?

[jaylees]

Hi, I was wondering If it would be possible to control my Zero88 Fat Frog with a Raspberry Pi. Is there some way of connecting the GPIO on the Pi to the 8 Pin DIN on the Frog and then use a smartphone to control the pi? Cheers

[Jon Hole]

Hi Jaylees,

 

I'm sure there would be a way to do this, but, of course, you would still be limited by the limited functionality of the 8 Pin DIN on the Fat Frog.

 

If you try anything, do let us know how you get on!

[jaylees]

I will do!

 

You don't happen to know what voltage needs to be sent through the remote switches do you?

 

Thanks!

[KWR88]

The socket has 12v on pins 1-6, it is then basically looking for this to be pulled low when it is connected to Pin 8 which is the common pin.

When it detects this it will then carry out a "GO" next or "GO" memory X, depending on what you set up in the super user remote option. There are no other options available so it would be limited control

[kgallen]

Hi jaylees.

 

Just to elaborate on what Keith says, you will need to drive the remote input from something like an open-collector transistor, not a push-pull output stage. I don't know what the Pi has for GPIO and whether this can be configured push-pull or open-collector/open-drain. Whatever the stage, it would need to be 12V tolerant and you will end up needing to common the 0V of the Fat Frog with the 0V of the Pi. Given that both pieces of kit are powered from switch mode supplies and their grounds could be floating or at different potentials I'm not sure a direct connection would be the best idea. Maybe better to use an opto isolator like 6N139 to isolate the Fat Frog from the Pi (which is what I did with my wireless remote control, details of which used to be on this forum but have since disappeared over the various migrations...).

 

Here is some very useful information I got from Paul way back that elaborates on the input stage so you can come up with a reliable interface circuit between the Pi and remote inputs:

 

"The remote inputs on the Frog series have a 10K pull-up to +12V, then a 10K series resistor and some clamping diodes, before being fed to a 4051 mux and on to a micro A/D pin. The software simply looks for a voltage < 2.5V at the A/D pin to determine a remote switch closure.

A simple open-collector NPN transistor will be fine to trigger a remote input. The maximum collector current will only be 1mA or so, and maximum Vce is 12V, so really any old transistors you have lying around will do. You might want to put a current limiting resistor in your circuit too, to protect your transistors a bit in case someone plugs your remote thing in to a standard analogue control connector which may have a low impedance +10V supply on the pins. 100ohms or so should do, this will limit the maximum collector current through the transistors in case of a fault, and won't affect the voltage read by the Frog significantly in normal use. "

 

Hope that helps.

 

Kevin