# What's the deal with FV-1?



## bengarland (Jun 19, 2019)

I'm a bit confused with the FV-1 stuff, since some of the different "pedals" for this all look like the exact same PCB.

I'd like to order the development board (I think) so I can tweak things myself -- I'm somewhat familiar with AVR programming so I think I'll be able to figure out the FV-1.

Is there anything that the dev board does NOT have that the "regular" FV-1 PCBs do have? i.e. I'll be able to use the dev board as a regular pedal as long as I buy the corresponding PedalPCB EEPROM, right? I could turn it into an Octagon, Unison, Kaleidoscope, etc? Is ordering a dev board the most versatile "DIY" route to take? Or am I missing something by doing that?

And where does the "Pythagoras MultiFX Platform" ($10) PCB fit into this? e.g. the PCB for this and the Radium Springs is exactly the same, so what's the actual difference?


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## Robert (Jun 19, 2019)

Technically you can run any of the algorithms on any of the FV-1 PCBs.    The difference is the supporting circuitry around the FV-1 IC.

The Pythagoras and Arachnid PCBs are functionally similar, except the Pythagoras supports up to three algorithms switchable by a toggle switch.
The Arachnid PCB supports eight algorithms switchable by a rotary switch.

The FV-1 Dev is similar to the Pythagoras PCB (three effects) with the addition of the USB programmer.      It is capable of reading and writing all 8 slots on the EEPROM, but it can only utilize the first three.  

The Unison, Kaleidoscope, ThreeVerb, D3lay, and Radium Springs all use the Pythagoras PCB.
The Octagon and Module8 use the Arachnid PCB.

The Organ Donor, DMD-2 are PCB specific.   You could run their algorithms on any of the other boards, but because there is unique circuitry to each of those PCBs they won't behave properly.

The reason the Arachnid and Pythagoras PCBs are available _without _an EEPROM is for those who want to design their own, or want to create a custom set of programs using the Custom EEPROM Builder tool.  https://www.pedalpcb.com/product/eeprombuilder/


Programming the FV-1 is _quite_ a bit different from AVR programming.   The FV-1 compiler uses a dialect of Assembly, and requires more than just an understanding of the language... You'd also need a decent grasp of audio DSP concepts.

Also, the SpinAsm compiler is only compatible with Windows.  So far it hasn't been run successfully in Wine on Mac or Linux...   I suspect it will probably work in a virtual machine, but I haven't had a chance to try that.

The good news is that you can use the SpinCAD graphical design tool to create algorithms without needing to dive head first into the code.


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## bengarland (Jun 19, 2019)

That all makes sense.

Just to clarify:

1) If I want to use any of your programs, then I have to buy the programmed EEPROM from you (either by a board bundle, single program chip, or multi program chip). Then this EEPROM chip can be plugged into the Pythagoras or Arachnid PCBs. Or I could also use any EEPROM chip that's already loaded with custom code (e.g. from another vendor, or loaded by someone with a Development board). But these boards cannot load code on their own since there's no USB etc.

2) If I want to run free programs (e.g. http://www.spinsemi.com/programs.php) or design my own, and load them onto an EEPROM, then I need the Development board.

Correct?


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## bengarland (Jun 19, 2019)

3) Are all of the EEPROMs not available via the Builder? e.g. if I want the Unison Double Tracker effect, is ordering the Unison Double Tracker PCB the only way to get it?

4) What's the difference between the Arachnid and the Octagon?

Thanks!


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## Robert (Jun 20, 2019)

You can load programs onto the EEPROM using the FV1 Development board, or any 24LC32A compatible EEPROM programmer.

No, a few of the algorithms aren't in the builder.    Not for any particular reason, I just haven't had a chance to update it.

Arachnid is the PCB.  Octagon is EEPROM + Arachnid PCB together.

The Arachnid and Pythagoras come with no EEPROM on their own.


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## bengarland (Jun 20, 2019)

For the programs in the custom EEPROM, are there any sound samples available? I can guess what some of them might sound like, such as Spring Reverb and Chorus (and even then, there could be huge variations depending on the implementation)... but other ones like Hypernova Reverb I have no idea. It would be nice to get some demo sounds and a better description of what these effects do, what parameters are adjustable via the 3 knobs [okay I now see the knob parameters listed on the various pages for the PCBs that include those effects], etc.

Then again, maybe I should just order them all


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## Robert (Jun 20, 2019)

There are a couple YouTube videos showing some of the patches, beyond that I don't have any official demos at this point.


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## the_grumpy_gnome (Jun 21, 2019)

Robert said:


> Technically you can run any of the algorithms on any of the FV-1 PCBs.    The difference is the supporting circuitry around the FV-1 IC.
> 
> The Pythagoras and Arachnid PCBs are functionally similar, except the Pythagoras supports up to three algorithms switchable by a toggle switch.
> The Arachnid PCB supports eight algorithms switchable by a rotary switch.
> ...



It took me a long time to figure this out


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## the_grumpy_gnome (Jun 21, 2019)

@bengarland  Here's a thread where I posted some samples:  https://forum.pedalpcb.com/threads/fv-1-sound-samples.549/#post-3108


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