thoughts on Digitech Space Station eprom copying?

[Govmnt_Lacky]

Ian....

Sounds promising however, adding even more passive to the circuit is going to create more strain on the regulators. I fear adding 3-4 more ICs with supporting components will push it over the edge.

[slacker775]

Instead of 4 eeproms, perhaps 1 4mb and do a similar and switch technique?

[marmaliser]

Thanks Ian! 

To sum up. The A14 connection (in my build) is only connected to its place on the XP PCB. No pull up resistor to 5V and nothing to pull it down to 0V. Essentially, the 83C154 is controlling the switching. The only lines that I am currently controlling is A15 and A16.

I am using the 27C1001 EEPROM built by Dino and one of marmaliser's adapter PCBs. No relay installed for Dry signal in XP100 mode.

So, according to this.... here is the coding for the A15 and A16 lines per pedal:

XP100 = A15: 0V  A16: 0V
XP200 = A15: 5V  A16: 0V
XP300 = A15: 0V  A16: 5V
XP400 = A15: 5V  A16: 5V

Just to confirm I have just removed the connection to A14 off of a working XP all + build and it still works just fine

[digi2t]

Thanks Ian! 

To sum up. The A14 connection (in my build) is only connected to its place on the XP PCB. No pull up resistor to 5V and nothing to pull it down to 0V. Essentially, the 83C154 is controlling the switching. The only lines that I am currently controlling is A15 and A16.

I am using the 27C1001 EEPROM built by Dino and one of marmaliser's adapter PCBs. No relay installed for Dry signal in XP100 mode.

So, according to this.... here is the coding for the A15 and A16 lines per pedal:

XP100 = A15: 0V  A16: 0V
XP200 = A15: 5V  A16: 0V
XP300 = A15: 0V  A16: 5V
XP400 = A15: 5V  A16: 5V

Just to confirm I have just removed the connection to A14 off of a working XP all + build and it still works just fine

I confirm, confirm this. 

[MüThing]

By working do we mean running or functioning here?

[Govmnt_Lacky]

By working do we mean running or functioning here?

Both! Disconnecting the A14 connection has no effect on the pedal functioning/running like it does before it was disconnected. All it will do is remove the additional current drain that is caused by having that pull down resistor in place.

[MüThing]

That's strange, I wonder why it was thought to be needed in the first place.

[digi2t]

That's strange, I wonder why it was thought to be needed in the first place.

Keep in mind that this has always been a work in progress, not to mention a big fat learning curve for some (read "me"). Hence the occassional updates/corrections to the build doc are to be expected. Just when I think that I've made the ultimate update to the build doc, someone finds something new that needs to be addressed.

This is what I call "learning". 

[mitchschaft]

Here is just a random thought to an issue I have with mine. You mention removing A14 will get rid of current drain. Could this current drain be responsible for my xp-All+ occasionally not switching from xp100 mode to the other modes? Occasionally, when I flip the switch from xp100 mode to any other mode, it's silent and nothing happens except for the click. I have to power cycle it to get anything out if it. Or am I totally off base?

[digi2t]

Here is just a random thought to an issue I have with mine. You mention removing A14 will get rid of current drain. Could this current drain be responsible for my xp-All+ occasionally not switching from xp100 mode to the other modes? Occasionally, when I flip the switch from xp100 mode to any other mode, it's silent and nothing happens except for the click. I have to power cycle it to get anything out if it. Or am I totally off base?

Easy test; Disconnect the A14 wire, and see if it ever happens again. If it doesn't, could well be. If it does, suspect another cause.

[Govmnt_Lacky]

@mitchshaft

May be a stupid question but....

Are you using stacked EEPROMs for your conversion or are you using the 27C1001 EEPROM with adapter?

[mitchschaft]

Just the 27C1001. I was going to mention that, but I thought the XP-ALL+ denoted it. My bad!

Of course I didn't think to just disconnect it myself . I'll see what happens.

[Govmnt_Lacky]

@mitchshaft

Are those 4K7 resistors you are using for pull-ups on the adapter board? If I were you, I would change those to at least 10K. 22K is best.

[mitchschaft]

Yeah, I put in what the build doc said. I'll swap 'em to 22k.

[mitchschaft]

Swapping the 4k7's to 22k caused the channel changing issue to occur every time instead of occasionally. I don't know if that's a coincidence or not. And, when I remove A14 from the rotary switch, the XP100 channel is blank on the screen and no sound, the Xp200 channel displays '88' with no sound, but the xp300 and 400 work fine.
I have some gremlins in my build.

[Govmnt_Lacky]

Swapping the 4k7's to 22k caused the channel changing issue to occur every time instead of occasionally. I don't know if that's a coincidence or not. And, when I remove A14 from the rotary switch, the XP100 channel is blank on the screen and no sound, the Xp200 channel displays '88' with no sound, but the xp300 and 400 work fine.
I have some gremlins in my build.

The 22Ks should not do that. The only think it should do is reduce the current draw when the channel(s) are held HI.

It sounds to me like you need to trace ALL of your wiring from the rotary to wherever they go.

[mitchschaft]

Ok. Knowing me I have something backwards. Especially since disconnecting A14 causes all those troubles when it's not supposed to make a difference. Or I even might have A14 mixed up with 15 or 16 in my head.

A14, 15 and 16 are clearly labeled on the perfboard pics in the doc. With the oshpark board it's not and I assumed A14 is the one hole moved from the right of the perfboard to the left on the oshpark board closest to the other connections. But I used my meter to check continuity to see where they attached to. So there's no telling lol.

[Govmnt_Lacky]

Did you remove the pull up resistor as well? If you didn't, that A14 line will constantly be pulled up. Removing the wiring will only remove the potential for that line to go LO.

[mitchschaft]

Oh, I didn't see anything about removing resistors. I'll go back and re-read.

[Govmnt_Lacky]

Oh, I didn't see anything about removing resistors. I'll go back and re-read.

I don't know if it is specified but, that resistor ties the A14 line to HI cnstantly. It is the line to the rotary that controls whether or not that line goes LO.

Not 100% sure it will change your problem but, I am sure it is not needed.