Difference Between Spin FV-1 and EEPROM

[natron_mn]

I'm less than a newb when it comes to digital effects. I was looking at some FV-1 pedals on pedalpcb.com and saw that each pedal has an FV-1 chip and an Attiny (the EEPROM).

I'm wondering why each digital circuit has those two things? I also may not even be using EEPROM correctly. Would it be correct to say any Spin based pedal has an FV-1 and a microcontroller (the Attiny in the case of pedal pcb)?

I thought the FV-1 had the algorithms coded to it, so what is the microcontroller doing?

Sorry if this is answered already. I've searched the internet with no luck, probably because most people know what they're doing and don't need to ask!

[octfrank]

The FV-1 has an internal ROM with set programs. You can use the internal programs if you want to, you cannot change them.

If you want to run your own code you can use the free SpinASM assembler to assemble the code and write it to a 24LC32A EEPROM and the FV-1 can read code from that. Max of 8 programs can be stored in the EEPROM.

For more advanced items (more than 8 programs, build programs on the fly, etc.) you can use a micro to emulate an EEPROM. This is a much more advanced topic and requires a real good understanding of assembly for different platforms, emulating interfaces, etc.

[natron_mn]

Are the set programs reverb programs?

So the EEPROM stores the code but doesn't "do" anything with it - it is the FV-1 that utilizes that code?

And if the EEPROM isn't there, does the FV-1 just run its internal set programs, or does it require a microcontroller to function?

[lietuvis]

I think micro controller is used for to select programs, wether internal on FV-1 ROM or external on EEPROM, depends on pin 13 on FV-1 status. grounded is to use internal rom. Instead of a micro controller you can use rotary encoder which is hard to find and expensive, or use 8 position rotary switch with diodes to replicate rotary encoder. In other words micro controller is for program selection and EEPROM is to store your custom programs. You can find schematics on web. something like this I borrow from David Rolo:

[natron_mn]

Thank you! So if the programs are on an external EEPROM, then what is the FV-1 used for in that instance?

[lietuvis]

Think this way your FV-1 is tiny computer with analog inputs and outputs and processing your sound by program used, yes it does have memory for programs that are built in but you cannot change,delete or write there on FV-1, only change parameters with pot's 1,2,3. With EEPROM, which is external memory with no processing you can write your own custom program (instructions for FV-1 what to do) for reverb, delay, etc...
FV-1=computer , EEPROM=memory like hard drive.
Hope this more understandable

[natron_mn]

Ah, I think that clears it up - thank you very much!