Multi-EEPROM daughterboard

[Bricksnbeatles]

It would be cool if there was a daughterboard available to allow for selection between multiple EEPROM chips in addition to the fv-1’s default presets. I’ve seen it done in the Mimir’s Well (which is an awesome pedal project that I highly recommend) by MAS Effects using a 3pdt on-on-on toggle switch, but i assume it could also be done with the appropriate rotary switch to access even more depending on what’s preferred. In the Mimir's Well it allows 8 programs from EEPROM-A, 8 from EEPROM-B, or the 8 that are default with the FV-1, depending on the position of the switch.
It would be a great addition, like the clock module, in most of the existing FV-1 multi effect projects available from pedalPCB, and could be especially useful in the forthcoming Binaura stereo multi effect kit.

 

[Bricksnbeatles]

I’ll be honest— after reading a bit more about the Fv-1 and looking at the Mimir’s well schematic, I’m not sure if that’s even something that can be done (using not only two switchable EEPROMS, but also the stock programs) without an arduino nano (though I *think* it can— after all this is a thing). It seems that it would be simple enough to swap between two EPROMs by just switching pins 5 and 6 of the respective ICs with a dpdt, leaving pin 8 of both ICs tied to the 3.3v, and everything else tied to ground, though I don’t know if the EEPROM chips can be damaged by having the voltage applied to them while pins 5 and 6 are floating (when the other chip is selected)— otherwise just a 3pdt could be used, with the voltage being disconnected from the inactive eeprom as well

If that’s doable, it’s all good and well, but what would make it even cooler is if, like the Mimir’s well, the stock programs of the FV-1 could somehow be accessed. Thats the part I’m really not sure of due to my very limited understanding of the digital side of things… it seems that on any of the PCBs that use an EEPROM, the native programs of the FV-1 can’t be accessed in lieu of an EEPROM without some sort of fairly complicated workaround. Anyone care to let me know if I’m making any sense? It is late after all, so I’m probably not as articulate as I’d be in the morning.

 

[phi1]

Great questions. I definitely recommend reading through the fv-1 datasheet for details if you plan on going rogue with fv-1 project (which is a lot of fun).

accessing the original programs can be done easily, all you have to do is ground pin 13. You can tie a wire off from the resistor leg that’s connected to pin13.

for switching between eeproms, mr. Pedalpcb informed us that you can connect pins 5&6 of both, and then control by only changing pin1. Whichever eeprom has pin 1 grounded will be active. The inactive one should be pulled to 3.3v through a resistor. Based on this I did a dual eeprom build. Read through the thread, there’s also a nice stripboard layout by p_wats.

Arachnid - Dual Eeprom

This is my 2nd Arachnid build, my first was the old version with the potentiometer to select patches. This new version with the 8-way switch is much nicer. Since PedalPCB hasn't released a dual eeprom board yet, I had to cobble together my own on perfboard. If @PedalPCB does release a dual...

forum.pedalpcb.com

It’d be awesome if pedalpcb made a pcb for this, would be way easier than any of those perf or stripboard layouts.

anyway, based on the above I think you could access 2 eeproms and the stock using an on-on-on dpdt switch.

 

[Robert]

I'm on it. Any objection to using SMD EEPROMs to keep things smaller?

 

[phi1]

Seems that smd might be harder to re-flash after installed, especially if pins 5 & 6 would be connected between the eeproms. For me re-flashing is important, not sure how much for others. 16 or 24 patches is kinda unwieldy to memeorize, so I understand why people label what each patch is with no intention to change.

 

[Robert]

You'd reflash by connecting to the SCL / SDA lines and selecting the active EEPROM with the rotary switch.

 

[Bricksnbeatles]

I'm on it. Any objection to using SMD EEPROMs to keep things smaller?

I personally have no issues with SMD, assuming it’s not an absurdly small package size. Going with SMD though, it might make sense to put spots for three EEPROMS then since it won’t add a ton of size anyway, and then just put jumper pads so someone can choose to either have three distinct EEPROMS and no access to stock programs, or just do two, and jumper the one for the middle switch position so the stock programs are used. I drew up a diagram that I can post later if you don’t get what I mean.

the only issue I could think of with SMD is the fact that a lot of people probably aren’t flashing their own eeproms, and not being able to socket them might be a drag for them. Then again, maybe this would be a good incentive for them to learn to do it themselves.

 

[Bricksnbeatles]

16 or 24 patches is kinda unwieldy to memeorize, so I understand why people label what each patch is with no intention to change.

Not the *easiest* to memorize for everyone, but I think with sone careful planning, it wouldn’t be too tough (for example have one EEPROM dedicated to delays and reverbs, and another dedicated to modulation, with the programs put in a logical order).

 

[Robert]

Going with SMD though, it might make sense to put spots for three EEPROMS then since it won’t add a ton of size anyway

I was thinking eight EEPROMs and you could load the stock programs on one of those if you wanted (or not).

 

[Bricksnbeatles]

I was thinking eight EEPROMs and you could load the stock programs on one of those if you wanted (or not).

Ah, yeah I had thought about that— using a rotary switch, but I figured i was the only person in the world who wouldn’t think that’s complete overkill lol. I’m glad I’m not alone in my passion for excess. I figured most people would be happy with just a dpdt on-on-on mini toggle (or a 4pdt if they wanted to add a tri-color status led that has a different color when each of the three banks is active).

 

[Feral Feline]

Bump to show interest.

SMD okay, so long as it's the biggest SMD possible!
Also, 8 EEPROMs would be wild!

 

[Bricksnbeatles]

Bump to show interest.

SMD okay, so long as it's the biggest SMD possible!
Also, 8 EEPROMs would be wild!

To add to this, I think maybe both an smd version and a non-smd version would be ideal. There could be a version to be used with an on-on-on dpdt toggle switch and a trio of DIP EEPROMs, and then the smd version for use with a 1p8t rotary switch and eight SOP EEPROMs.
I think the three toggle positions might be of more use to many people than the slightly excessive 8 rotary positions, and the people using the three chips are more likely to want to be able to socket the chips and swap them out anyway.