Simple Digital Delay

[Ice-9]

For the delay time I would probably set the limit to 800ms each so that when the delay pot is set at max you will get your magic number of 800ms+1600ms. A single pot can control both FV-1 chips without the need for a dual gang. This way the delay taps will keep the time with each other, ie the second delay will always be double the first.

For the multi jack outs you will have to think that one through carefully for how it is switched and mixed.  The DSP chips will each need an EEprom for your program but I expect you already knew that.

[nickbungus]

For the delay time I would probably set the limit to 800ms each so that when the delay pot is set at max you will get your magic number of 800ms+1600ms. A single pot can control both FV-1 chips without the need for a dual gang. This way the delay taps will keep the time with each other, ie the second delay will always be double the first.

Sound Great

For the multi jack outs you will have to think that one through carefully for how it is switched and mixed.

Switching: perhaps having a 0ms delay time when the effect is not engaged might be an easy hack. 

Mixing is a bit trickier.  I was thinking using the stereo outs from the first chip, have left going to 1 output and right going to the 2nd chip, but this will need some thought in implementation.

The DSP chips will each need an EEprom for your program but I expect you already knew that.

Looking at the datasheet, there's a schematic in there using a 24LC32A.  Will these cut it?  I've added them to my RS Components basket but yet to order.

[Ice-9]

This is how I would consider connecting the two DSP's together, I have used the datasheet to get an idea of the signal flow, I have just used a simple buffer as the input, you might want to use a more complex preamp section possibly.

Connecting one output of the FV-1 to the input of the second FV-1 is done using the standard filtering from the datasheet.

This might give you a head start on the basic DSP part. A pot is connected to both FV-1 pot0 inputs which can be used to control the delay time and I would think about using 2 more pots to control the delay level of each FV-1 chip separately if that's what you require.

You will need to look at adding the outputs from the FV-1's to the mixing section etc.

[nickbungus]

Thank you Mick - thats amazing.  Any chance I can get a higher res version of the schematic

I'm reading up on SpinASM now.

[Ice-9]

Here is a larger drawing, note that this is just a small building block and idea of how the 2 FV-1 chips could be used, there will still be a lot of stuff to add to make a complete effect.

1st FV-1- left output will carry 800ms delay to output mixing
1st FV-1- Right output will pass 800ms delay to the 2nd FV-1

2nd FV- 1 left output will carry 1.6 second delay to output mixing
2nd FV-1 Right output not  used  (possibly use to add feedback)

The Eeproms you linked to are the correct ones.

I hope this gets you started with your plan. I suppose there are many other ways to build what you are looking for and this is just one option.

[nickbungus]

note that this is just a small building block and idea of how the 2 FV-1 chips could be used, there will still be a lot of stuff to add to make a complete effect.

Thanks, I appreciate that but I didnt have a clue so this is such a massive help.  My plan is to etch your schematic and then breadboard the mixing stage.  Looking at how Electric Driuid did his for inspiration.

Thank you so much for your help and time Ice-9.  It is truly appreciated.

[Ice-9]

note that this is just a small building block and idea of how the 2 FV-1 chips could be used, there will still be a lot of stuff to add to make a complete effect.

Thanks, I appreciate that but I didnt have a clue so this is such a massive help.  My plan is to etch your schematic and then breadboard the mixing stage.  Looking at how Electric Driuid did his for inspiration.

Thank you so much for your help and time Ice-9.  It is truly appreciated.

Yes, Electric Druids Digi delay is also a very good echo to look at as it has up to 4 seconds of delay there may also be a way to tap the delay for the two separate echo divisions, worth having a word with Tom as it might be possible to alter the code to allow this.

You might also want to check out the fV-1 project thread here, it is the first FV-1 project I brought to this forum and there have been hundreds of that pedal built  but be warned it is a HUGE thread.  Lots of info on many things as well as how to program the eeproms etc.

[nickbungus]

Exciting times!!  Orders are starting to arrive.  My schematic is nearly finished for my prototype.  Just trying to figure stuff out!

Its hard to follow the original FV-1 from Mick as its old and a lot of the image links are dead.

I take it this is how to connect my Pickit 2 programmer to the EEPROM?

Connections for 24LC devices
        ---------------------------------------
        PICkit 2 Pin             24LC Device Pin (DIP)
        (2) Vdd !                8 Vcc
        (3) GND                  4 Vss
        (5) PGC                  6 SCL (driven as push-pull)
        (6) AUX                  5 SDA (requires pullup)
                                 7 WP - disabled (GND)
                                 1, 2, 3 Ax pins
                                    Connect to Vdd or GND per
                                    datasheet and to set address

   ! 24LC devices may not program properly below 3.6V VDD.
          This is a limitation of the PICkit 2 AUX IO pin.

[Ice-9]

If you fit sockets for the EEproms then you can program them off board, the pin connections you have listed look good.

[nickbungus]

If you fit sockets for the EEproms then you can program them off board, the pin connections you have listed look good.

Really?? That sounds great.

Is it as simple as just putting the EEPROM on a bread board, match the pins to the Pickit2 device and then load from the configured Development Programmer? 

No other circuitry required?  Then plug it into my main board?

[Ice-9]

If you fit sockets for the EEproms then you can program them off board, the pin connections you have listed look good.

Really?? That sounds great.

Is it as simple as just putting the EEPROM on a bread board, match the pins to the Pickit2 device and then load from the configured Development Programmer? 

No other circuitry required?  Then plug it into my main board?

Sort of,
You can use the Spin development program to build your effects program and save as a HEX file. You then use that HEX file with the Pickit2/software to program the EEprom.

Yes you can just wire up the pickit2 and eeprom to breadboard.

[nickbungus]

Sort of,
You can use the Spin development program to build your effects program and save as a HEX file. You then use that HEX file with the Pickit2/software to program the EEprom.

Sorry, I knew that.  Had read it a few times in the posts but I had a brain fart when writing my post.

Trying to lay my hands on SpinCad but I havent had confirmation from the HolyCity forum.  If anyone can send me a link, that would be most appreciated.

[nickbungus]

Trying to lay my hands on SpinCad but I havent had confirmation from the HolyCity forum.  If anyone can send me a link, that would be most appreciated.

Its ok, Larrys let me into his Digital world and I am a digital girl!  I thought I was analog only but times are achanging!!

[Digital Larry]

Its ok, Larrys let me into his Digital world and I am a digital girl!  I thought I was analog only but times are achanging!!

Glad we were able to work that out.  Now come to grips with the fact that most people want their digital delay to sound "more analog".

Hint - high pass and low pass filter before the delay.
Extra credit - push the high pass farther up in frequency than you might think.  I love this sound!  It keeps an element of "delay-ness" and yet keeps a lot of spectral clutter out of the sound.

Whether DSP emulates some piece of analog gear is almost completely unimportant to me.  Whether it sounds great is quite important!

[nickbungus]

Loving the SpinCad!!  Still finishing off my schematic but I'm looking at SpinCad trying to work everything out.

My question is to do with the switches on the FV-1.  I cant seem to find any reference to them in SpinCad and on the datasheet apart from the  schematic. 

I was hoping they could be used as controls but I'm now starting to suspect they are solely for toggling between patches.  Is that true?

[Ice-9]

If you are meaning the S0-S2 switches, then yes they are for selecting which one of the 8 effects programs are selected from either the internal or external EEprom locations.

[nickbungus]

Thanks Mick, thats somewhat scuppered my design!!

[Digital Larry]

SpinCAD lets you work on 8 patches in a "bank".  It is possible to think of a switch as a control, e.g. long/short delay times but then you have to start with a patch (e.g. patch 0, all bits are low) and make copies of it and then edit those things in 3 dimensions so to speak, so that patches where bit 0 is high are all short delay, and when bit 1 is low, are long delay, etc.

Requires a bit of planning but actually can be done.  The only real downside is a bit of a glitch is possible when switching.  You can also be tricky if you like and add extra differences not strictly associated with what you said the switch is supposed to control.  A switch could be chorus/phase which makes major differences in the algorithm.

[Ice-9]

I Just noticed a typo on the basic buffer input C8 should be 100n not 1n

[nickbungus]

I'm just finishing off the schematic and then I'm going to tidy it up.  I've got 2 isolated outputs for the 3 amp setup that route the signal back to the main output if a Jack isnt present to avoid ground hum.  Not sure if I need to add opamps to mix the signal back into the main output if there isnt a conncetion? 

Also, I think I'll add 3 external level pots.  Should help get the mixing if required.