thoughts on Digitech Space Station eprom copying?

[digi2t]

Geez guys, let me tell you... I'm really not that smart, but I can put 2 and 2 together on occasion. I'm really pushing the envelope on this one, including what little intelligence I have in this area. I'm just really praying hard that it will work. In the meantime, got the adapter done;













Although I always respected/admired Rick Holt's (frequencycentral) perf board soldering, that respect has reached a whole new level after having tried it myself. Beading solder is no easy feat when you've never done it before. I consider myself lucky that I managed to pull it off. Adapter passed all continuity and short checks with flying colors.

As shown above, I mounted it into the 28 pin socket already on the board, just so I could see how high it sits. It basically the same height as stcking 3 EPROMS (my EPROM's not plugged in all the way, I know, I know). If I solder it direct to the main board, it'll be 2 EPROM's high. Not bad considering that all four programs are on one chip.

Now I'm off to figure out the program switching configuration. OH JOY!!!! MORE F*&KING BINARY!!!!

My brain hurts....

[digi2t]

http://www.ebay.ca/itm/DigiTech-XP-1000-EFFECTS-XP400-XP300-XP200-XP100-SPACE-STATION-VERY-RARE-ITEM-/400336352882?pt=UK_Guitar_Accessories&hash=item5d35e7f672

Why is it, there's never a "bust a gut, rolling on the floor, tears gushing from the eyes, knee slappin'" smiley, when you need one.

[Govmnt_Lacky]

Bargain basement pricing!! 

Thinking about putting my original XP-ALL on the bay to raise funds for Xmas. Dont think I will go as high as that joker though 

Of course... if the bidding goes that high then............... I wont turn it down!! 

[digi2t]

Here's a vero adapter as well. Slightly bigger board, but still enough room under the hood to fit. Should be much easier to solder together as well.

[slacker]

I have no use for any of this stuff, but just wanted to say that's some great work, very nicely thought out.

[digi2t]

I have no use for any of this stuff, but just wanted to say that's some great work, very nicely thought out.

Well, thanks for the compliment Ian. I`m really hoping that it works though. As far as I know, using the 27C1001, and the program switching scheme is all theoretical. I haven`t come across anything to validate it, so I`m really out on a limb here. A very thin limb at that. I lifted the idea from here;

http://www.iroczone.com/2009/10/understanding-how-the-code-switching-eprom-circuit-works/

Yes... a hot rod site. Had to read it a kazillion times before it made a bit of sense to me. I should have stayed awake during those computer labs back in high school, but nooooo, I would never use this shit. Right?

Don`t ask how I came upon it. Just Google surfing.

[digi2t]

IT WORKS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

IT BLOODY WELL WORKS. 

All four progs on one chip, and by switching addresses via the rotary, I can boot to the XP mode I want. FREAKIN' AMAZING!!!

For those of you playing along at home, here is the switching chart. 0 = LOW (go to GND.), and 1 = HIGH (disconnect from GND.)

A14  A15  A16
0      0      0   = XP100
0      0      1   = XP200
1      1      0   = XP300
1      1      1   = XP400

This is just WAY too cool! 

I'll draw up a proper wiring diagram soon, for all the switch poles. The only thing left to test now is the relay to restore stereo in XP100 mode.

Back to the bench!! 

[Govmnt_Lacky]

DINO!!!!!

You da' MAN!!!

Im sure the relay will work too. The theory is sound and I am sure the implementation is spot on 

[digi2t]

Relay tested, works, and I got an ultra bonus. It gives me both sides wet, rather than the original left wet, right dry. I'm not really sure why just yet, but man!!, I will take that! I've updated the drawings, because I forgot to mark in the Vss wire to the chip. I've also included the switch wiring.

Both boards;



Clear jumper view of perf board (vero is pretty clear);



and the switching layout;



I'm really stoked about the fact that the relay is giving me both sides wet. I really wasn't expecting that. He shoot's... HE SCORES!!!!!

[Govmnt_Lacky]

DINO.... man.... you are makin' me look bad!   

I am now wondering since you are essentially bypassing that J113 transistor with the relay, whether or not you would still get a wet output with it bypassed in the 200, 300, and 400 modes 

Essentially, is that transistor necessary? (Q5)

[digi2t]

DINO.... man.... you are makin' me look bad!   

I am now wondering since you are essentially bypassing that J113 transistor with the relay, whether or not you would still get a wet output with it bypassed in the 200, 300, and 400 modes 

Essentially, is that transistor necessary? (Q5)

No, you won't. You need that fet there to bring the right side info up in 200, 300, and 300 modes. Since there is no right side info coming from the board in 100 mode, what we're doing here is jumping the fet, and bringing back the dry signal. When we go into the other modes, the relay opens the contact, as if we pull the jumper out, so we get the wet signal on the right side as per normal. I err'd before claiming that I had both sides wet, I guess my hearing was feeling in a "glass half full" kind of mood. We are now in stock trim in 100 mode.

I guess if I really wanted to, I could use the relay to bring the left wet signal to the right side as well, giving me full wet all around, but I'll leave it for now. I want to explore the dynamics of it as is first.

I did have a bit of a scare for a moment there, when the 200 mode wouldn't boot up. I realized after a while that I had mixed up the A15 and A16 wires on the switch. I even thought the chip was to blame, but no, simple faux pas on my part. Everything fits and works A1+. I'm really happy with the switch. Handles everything, and is nice and compact.

So, without further ado, I present the XP-ALL+.

The mountain has come to Mohammed....

[LocalToast]

I'm incredibly impressed with your guys' work. One of these days I'll try implementing this in my XP-100! Very awesome.

I was wondering if anybody had some insight on adding an additional control element to the XP board. By default the pedal is attached to an LED internally that moves further/towards a photoresistor to produce varying resistances.

I thought it would be cool idea to add a digital potentiometer to this circuit which could be controlled via MIDI or CV input, sort of like the Molten Voltage "Molten Midi" controller for the latest MIDI-enabled Whammy pedals. (video demo below) Basically, I'm a cheapo and want to "modernize" my pedal. Any thoughts on implementing this? I don't want to desolder anything or move anything because it may become uncalibrated if I do so, and I really don't want to screw it up!

[digi2t]

Technically, I think it would be possible to control the whole thing via MIDI. Even the mode changes. You could build a MIDI controller for it, into a Crybaby shell, with all the pot and switching functions coming from the wah. The advantage to that would be saving floor space. If you're a "rack junkie", like myself, stick the unit in the rack, and control it with a smaller footprint.

I'm sure that there are a mess of other opportunities that MIDI'fing it could offer, but I can't think of any right now. I just got up, and I haven't had my first cup 'o java yet.

[LocalToast]

My idea was to hook up a MIDI keyboard to a digital pot so that instead of controlling the whammy pitch with the foot pedal, control it with a MIDI device. For example, play a guitar note, maybe freeze it with a freeze pedal, kick on the whammy octave up mode, then go crazy on keyboard.  Or be a real bum and just program a bunch of arpeggios. The possibilities are endless, I wonder how this kind of control would work for the other XP models.

The only problem I can foresee is the microcontroller not playing nice with a variable resistor other than the stock LED/photoresistor configuration. I tried to deceive the pedal during calibration by not moving the pedal fully back and forwards but it just gave me an "Er" on the LED display. So maybe it has a set of "accepted" resistances that it compares against to see if the calibration was precise enough.

I think I've been letting my mind run too far with this pedal, I hope I can actually make something cool out of it!

[digi2t]

TECHNICAL UPDATE!!!!

If you're contemplating the output volume mod, please DO NOT use an A100K dual gang pot specified in the build document. Use an A1M dual gang instead.

I found that with the 100K, the closer you get to ground (min. volume), the more you'll hear a whining noise bleed into the audio. This whining might be from the power supply end of things, or maybe from the audio sides of the chips themselves, I don't know.

Anyhow, a 1M pot(s) provides enough resistance to prevent this noise from bleeding into the audio. The volume control is also better with the 1M, than with a 100K.

Build document will be updated shortly. 

[3080]

with a PIC it would be simpler, but this should work too.
just an idea... to control the program change with a push button, and monitoring with a RGB LED.
remarks and corrections are welcomed!

[LocalToast]

As someone who has never worked with most of the components required to build this mod, I'm having some problems pinpointing the sockets, headers, rotary switches and knobs that I need. As far as what dimensions I should be looking for, I'm clueless. Digikey has endless options for narrowing down a search, but I don't know which options I should be fiddling with. (that's another issue, where else besides Digikey should I look?)

Any help would be really appreciated, whether it's exact dimensions or just links to exact products. Sorry for my lack of experience, this has been the biggest obstacle so far for me to carry out this mod!

[Govmnt_Lacky]

As someone who has never worked with most of the components required to build this mod, I'm having some problems pinpointing the sockets, headers, rotary switches and knobs that I need. As far as what dimensions I should be looking for, I'm clueless. Digikey has endless options for narrowing down a search, but I don't know which options I should be fiddling with. (that's another issue, where else besides Digikey should I look?)

Any help would be really appreciated, whether it's exact dimensions or just links to exact products. Sorry for my lack of experience, this has been the biggest obstacle so far for me to carry out this mod!

This depends on which mod(s) you want to do and which unit you are modding.

Do you want to make an XP ALL? An XP ALL+? Do you want to just mod for a space station? Are you starting with an XP100?

Let us know what you are starting with and what you want to end up with and we can go from there  

EDIT: You mention an XP100 in a previous post. I will assume you are wanting to mod that. Just fill in the rest of the blanks if you would please 

[digi2t]

Like G_L mentioned, we would need to know exactly what you want to do. As for the parts, I rarely order from Digikey. They're a great place to shop, but I generally only get hard to find, or specialized stuff there.

Everything used in the mods is available on Ebay, generally at better prices than Digikey. Often times the shipping is free. Yes, you might have to wait a bit longer, but I prefer cash in pocket, rather than part right now.

[LocalToast]

My intention is to do the XP-ALL+ mod, I like a challenge! Also I actually already ordered everything so I'm waiting for a few things to come in the mail still.

I ordered the A1M dual-gang pot from Small Bear Electronics but neither of the knobs I bought (1 for the 6P4T, 1 for the A1M) fit the shaft. I emailed Small Bear for knob dimensions for the A1M.

I ordered the exact same 6P4T rotary switch in the tutorial. Hasn't arrived yet so one of my knobs may work for it, but could you show me a knob that would work for it?

I also just ordered the 32-pin and 3x 18-pin sockets from All Electronics... they were labeled "IC socket" so I will assume for now they will work, but like I said, I didn't know the pin spacing for the RAM, EPROM chips so it was kind of a shot in the dark. I assume it's a standard size, though. Still waiting for those chips to arrive from eBay.

Does the perf board need to have pads on both sides or just one? I was a little confused from the tutorial.

Thanks in advance!