Author Topic: TEENSY - GR55 mod - improved bank up/down with arduino/teensy  (Read 723 times)

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Offline sixeight

Lately I have been playing with Arduino/teensy boards, as I am building my own midi pedal.

Here is an idea I had:
Inside the GR55 it is quite easy to tap into the four foot switches. I have had a look and every switch is going straight to a wire connecting the top and bottom PCB.

What if I put an Arduino in between these wires? I could change the way these switches work.
* First, I could connect two external switches to the Arduino to serve as bank up and down switches.
* the Arduino could perform the switch sequence for bank mode (press 1 and 2 simultaniously on first bank change, then do bank up or down).  When selecting a patch, it could press the 3 button first and then select the patch.
* it could disable the looper or the tuner - which I press accidently quite often. Or maybe even add dedicated switches for these functions.
* it could even select the previous patch by pressing the button of the active patch again (which now does nothing)
* you could tap into S1 and S2 on the GK pickup and do something useful with that.
* S1 and S2 are available again, as they no longer have to do bank up/down.

Yes, it will void the warranty.

I will first build my MIDI controller. Maybe later I will try this project.

Offline Elantric

Re: TEENSY - GR55 mod - improved bank up/down with arduino/teensy
« Reply #1 on: June 18, 2015, 04:25:03 AM »
Quote
Inside the GR55 it is quite easy to tap into the four foot switches. I have had a look and every switch is going straight to a wire connecting the top and bottom PCB.

If you connect an oscilloscope to the internal Boss GR-55 patch change switches , you would see that these GR-55 internal switches are not tied to Ground. Instead they are always being scanned by the internal CPU's "scan" and  "data" lines  - similar fashion as to top  half of this schematic below
- its likely  your "mod" could damage the GR-55 CPU.

https://books.google.com/books?id=eVcEWDIeTYcC&pg=PT302&lpg=PT302&dq=scanning+mechanical+switch+microprocessor+-&source=bl&ots=kyfqUmr4ax&sig=jCSxlgtWr5_2A39YDAc4IX6UEdA&hl=en&sa=X&ei=v6aCVbuON4mLsAWqjKKABg&ved=0CCwQ6AEwAw#v=onepage&q=scanning%20mechanical%20switch%20microprocessor%20-&f=false



« Last Edit: June 18, 2015, 05:10:50 AM by Elantric »

Offline sixeight

Re: TEENSY - GR55 mod - improved bank up/down with arduino/teensy
« Reply #2 on: June 18, 2015, 08:58:57 AM »
The switches of the GR55 all connect to ground. To control these from the Arduino npn transistors will be necessary with open collector. That way it should not damage the GR55.

Offline Elantric

Re: TEENSY - GR55 mod - improved bank up/down with arduino/teensy
« Reply #3 on: June 18, 2015, 10:17:31 AM »
Good luck!

And keep us informed If you do stumble upon a GR-55 Service manual 

Offline JolietJake

Re: TEENSY - GR55 mod - improved bank up/down with arduino/teensy
« Reply #4 on: June 18, 2015, 04:55:25 PM »
Would it not be simpler to just tap into the S1 and S2 switches from the 13 pin port on the GR-55 anyway? You could simply use mechanical foot switches to perform the bank up/down then.

Offline sixeight

Re: TEENSY - GR55 mod - improved bank up/down with arduino/teensy
« Reply #5 on: June 19, 2015, 11:12:42 AM »
Would it not be simpler to just tap into the S1 and S2 switches from the 13 pin port on the GR-55 anyway? You could simply use mechanical foot switches to perform the bank up/down then.

I already have done that, but i don't like the fact that the Gr55 does a program change on bank selection. Also having the S1 and S2 buttons available as extra ctl pedals is much better.
« Last Edit: June 19, 2015, 11:14:51 AM by sixeight »