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[MarshallJMP]

Let's start with the midi pedal and we'll see how that works out.

BTW these guys sell what you need  http://www.manley.com/m162l.php

[MikeB]

Oooh, a project.  I like that idea.  I'll put together a wish list.  However, I did think: are we not just building a ground control?

So, this project got me to thinking about stuff that I like about the FCB-1010.  One of the features that I use is the ability for a switch to send on multiple channels at once.  That way I don't have to do any mapping in my units, the combinations of ADA patches and effects patches are dealt with by the pedal.  This seems to work pretty well but there is one thing that I have noticed and now I'm wondering if its because of this multiple channel thingy.  When I change programs, the G-Major is always just a tiny little bit behind the ADA.  Is this because the pedal is sending two messages and so the second one is delayed (I would have thought that it would be pretty much instantaneous) or just that the TC has more to do in changing programs and so takes longer.  The upshot of this delay is that I have to be a bit early on my program changes or else I end up missing the attack on my first distorted note/chord.  This is one of the reasons why I am going to setup a parallel loop so that the ADA signal can't get held up by something else.

[WickedBlade]

As some already know, I built my own MIDI controller a few years back, based on the MIDIBOX project (using an 8-bit PIC controller).
I've stopped documenting it midway unfortunately, you can find some info there.

It works but I had to cut out the loop switcher side of it because there was electromagnetic noise (from the PIC I think) that induced a 1KHz noise in the audio, very noticeable. The MIDI controller side is perfect for my needs, basically I can control my MP-1, Replifex, and Voodoo Labs GCX any way I want (99 banks of 5 patches), and with 2 expression pedals that I can assign freely.

I've started working on a PC Editor and SYSEX dialog with the unit, but I'm apparently too lazy to finish it.

I think if I had to start it all over I would go Arduino-based now.

[rnolan]

Let's start with the midi pedal and we'll see how that works out.

BTW these guys sell what you need  http://www.manley.com/m162l.php

Good idea  , I checked out the manley page, nice gear (5hz to 100khz (nice), you can do sony super audio as it goes flat to 100khz (2GHz sampling rate)).  I'd need to go for the big one to get enough aux sends ($25k ouch) and I only want/need 8 channels.  Also my dreamy idea is 2 RU max so it can go in an ADA rack rig.  I did a face plate layout a while ago (pencil on paper).  The idea also suffered from lots of scope creep (handle mic inputs/48v/phase reverse etc).  But from what the manley guys are doing, there is a market for it. So maybe one day..

[rnolan]

This one would work (http://www.manley.com/mmbb.php), 3 x stereo ins, run all the effects as inserts ( 

[WickedBlade]

I found an old picture of my DIY MIDI controller, I'm guessing it's quite close to what you're all aiming for, except that I gave a different role to some switches (I have basically 5 for patch selection, 2 for bank selection, one for Tap Tempo, and the 4 remaining ones are 'modifiers', basically they can send control changes to activate effects or pedals on the fly).

Not on picture but you can plug 2 expression pedals (you can see the labels for the inputs), and I have room for amp channel switching which I never got around to actually implement in software (can't remember if I actually did the hardware part).

And of course there are 2 buttons and 2 rotary encoders for parameter edition (knobs missing on the picture), an LCD screen and 2 digits LED display.

[MarshallJMP]

Hey Rnolan,why would like to have a tube based mixer?Just wondering how you did get this idea,did you try one and did you like it so much or....

WB,well i remember this project.We did discuss some solutions how you could try to get rid of the 1kHz signal.
Just a quick question,do you display the program number on the led or lcd display ,or both?Just wondering of the lcd is big enough to read the number.

[WickedBlade]

Yeah MJMP you were a big help with this issue. I think I understand where it comes from now.

Back to your question, the LCD display shows the name of the bank on the first line and the name of the patch on the second line. I find that quite legible, though small, but in a live situation it's faster to have a quick look at the 7-segment LED display. The LCD however is invaluable when it comes to edition.

[MarshallJMP]

What did you find out?

[MarshallJMP]

Just found this

http://www.mikroe.com/ready/pic/

Very cheap and it even has a bootloader so you can do updates with a pc and a usb connection.Would be nice to use it for a midi pedal.

[WickedBlade]

What did you find out?

IIRC, I believe the issue is electromagnetic, not a problem of actual signal noise. From what I gather, it is due to the fact that the PIC is programmed to regularly poll the 74HC165 in the Digital In module (DIN), to get the status of the switches/encoders and see if anything has changed. The polling is done at a 1kHz frequency which is the pitch of the noise I hear.

I'm not sure I've really eliminated all other possible causes, but I seem to remember that taking the DIN module out of the circuit eliminated the noise, whereas taking the Digital Out module (which uses 74HC595 chips to refresh the various leds and relays just as frequently) wasn't helping.

I've since thought of ways to be more clever in finding out if the 74HC165 need to be polled, but that would mean reprogramming the core software of MIDIBOX (the kernel, basically), which I have no desire to do (I have the skill and know-how, but I'm a lazy person )

[WickedBlade]

Just found this

http://www.mikroe.com/ready/pic/

Very cheap and it even has a bootloader so you can do updates with a pc and a usb connection.Would be nice to use it for a midi pedal.

I believe that using a PIC is more painful than necessary though. Some ARM chip or something like that would be easier to program. The PICs have many limitations, and I couldn't find a decent C compiler (SDCC is working but incomplete) let alone a C++ compiler, and this makes the programming side difficult. And I know from experience that programming the edition interface for that kind of pedal is actually quite a job (not difficult, but complex), and if you cannot use a decent language and are stuck with assembly you're basically missing a whole bunch of helpers and checks that a full-fledged language can provide.

It's still feasible (I did it in that limited C language that SDCC supports on PIC) but what would have been a breeze on many platforms was a tedious process here.

(And don't get me started on the Basic language, I'm talking decent language here)

[MarshallJMP]

Check out this C compiler for pic  http://www.mikroe.com/mikroc/pic/ it's free if you don't have more then 2k words of code.

The new 18F pics are alot better then the older 16F series.I just want to keep it very cheap and easy so anyone can build one and with the bootloader it's easy to update.

I use the basic compiler from mikroelektronika  because i hate programming in C,works like a charm.I wanted the pascal version but my son was also interested in programming (he doesn't had any experience) so i decided to go for the basic compiler,since it's quite easy to learn.
Now these compilers have alot of library's,this makes programming alot easier.Alot easier then the basic compiler i used for my midi patcher.
I'm actually making the hardware schematic now.How did you read the switches?I'm thinking of using a 5 x 5 matrix so you can hookup 25 switches,just hope it's quick enough.Did you use a 74LS165?

[WickedBlade]

You make good points MJMP, and I do hope I'm not so proud as too change my mind when good arguments come into play

That C compiler might be nice. I see it has its own IDE as well. I must admit I went with SDCC because that's what MIDIBOX advises. Also the other compilers I've looked at were all free/open source, so MikroC wasn't one of them.

That being said, out of curiosity I had a look at the program I wrote for my board, and it's 175 kbytes. And that's without even the core of the MIDIBOX software there, so we might get a surprise regarding the actual amount of code that your project requires.

Your point on the various families of PICs is very valid. But I used a 18F4620, which is still very basic, kind of like a Z80, but the most frustrating was the way it accesses memory, I also had to be wary of the executable size which is pretty limited on my PIC. The rest was mostly ok. I don't think you need much power anyway (except to do fancy stuff for playing with the expression pedals curves).

I understand your pain dealing with C, but as my daily job involves programming in C++, this is not daunting to me, and I appreciate the power of the language compared to Basic. But if you can get useful libraries it's still doable. In my opinion though, the executable produced with a Basic compiler would be much slower and bigger than the equivalent written in C/C++, and that is something to consider with PIC chips.
I did start with Basic when I was very young though, it's a nice and easy first step into programming.

All that being said, "if it works for you, then it's the right tool". Did I mention that I'm a software engineer? That may shed some light on my stance...

Anyway, as for the hardware, which is clearly not my field of expertise, all I can say is that I used cascaded 74HC165 chips, and that's only because it's what the MIDIBOX project is using.. I'm pretty lost when it comes to finding the right chip for an electronics project. I understand the basics of datasheets (part of my education, where I studied a wee bit in electronics) but that's about all. I don't know how to go about finding out a chip to get a job done.

While I'm at it, a word on the power supply. You're probably more aware of this than I, but using a 780x voltage regulator turned out to be a bad idea, because with the various LEDs and the LCD display, the current drawn makes the regulator go very hot, even with a heatsink attached. So I had to swap that for a chip I found on ebay, it takes almost the same space and the same pinouts as a 780x. I suspect it's just a cleverly packaged circuit using more traditional circuit (I cannot remember the chips involved right now, sorry!), not using a switching technique. That works well. Why did I use that obscure chip, you may ask? Because I didn't want to make a whole new PCB board just to change the power section (I'm lazy, I tell you!).

All this was so long ago! It appears I have not documented my project as well as I should have! Anyway, if you have more questions I'll be happy to oblige. Just remember that I'm a software guy, not a hardware guy

[MarshallJMP]

175kB!!! is that the program code or the hex file?I know for my midi switcher i had a hex code of 4kB and i used 129 bytes of eeprom to store the patches.128 patches and one byte to remember the last patch.I used 12 inputs directly for the buttons and 8 outs through a ULN2008 to drive the relais.And then Rx and Tx for midi out and midi in.Also attached was the LCD in 4 bit mode.I also used the 7805 and didn't even had to cool it extra.

I don't think you can compare a 18F4620 with a Z80,the pic is faster,has flash,ram and eeprom memory,uart i²c spi etc...
A Z80 was very basic even a 8051 had more altough it wasn't faster then Z80 at the time.

C is a language that you need to maintain,if you don't work with it on daily base it hard to get familiar with it.That's why i like pascal and basic i guess.I'm more of a hardware guy

Now the ready for pic board has a power supply on board,both 3.3 and 5V and you just need to hook up a wall adaptor (ac or dc).

Anyway gonna try the matrix thing for the switches (less ic's altough the 165 is a good idea).Look at this pic,it will give you an idea what i mean  http://www.extremenxt.com/matrix.html

As for the 7 seg led display I'll think i will go for a serial display like this one  http://www.mikroe.com/add-on-boards/display/serial-7seg-display/ The advantage is less connections and you don't need to refresh it,it's all done by the on board chip.

Don't know if we need an LCD or not,but it's easy to implement.