An Open Source Programmable Effects Switcher

Big Monk

Well-known member
Ladies and Gents,

A proposal: Let's open source and try to figure out how to make a 1032L based, microcontroller brained, programmable effects switcher. The inspiration is my powerful yet simple to use Joyo PXL8 Pro switcher:

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I love many things about the PXL8 Pro but really wanted something in the ballpark size of the PXL4:

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What you get at the core of both of these is 16-32 presets. The PXL8 Pro has the advantage of a Tuner out, Muting system and 4 programmable relay controlled Trigger outputs.

On the negative side, however, the PXL8 series, as well as the PXL4, have fixed, non-switchable high impedance opamp buffers on the input of the first loop and the output of the last loop. This is troublesome if you want to run a Fuzz into the first loop, so I had to modify my PXL8 Pro to have the buffer on a switch.

So, what the hell am I rambling about? Well, I already had the germ of an idea for a power supply using the 1032L enclosure. It's a bit smaller (4" "shorter") than the PXL4, but has more depth and equivalent width. I pinged @Robert and he had already been toying with the idea of a programmable switcher in a 1032L and he gave me some pointers, etc.

So let's look at the rough mockup:

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Size dictated me pushing the switches closer together. As opposed to the 77mm switch to switch width of the PXL series, these are 54mm apart. Definitely more than say a 125B with dual switches, but not ALOT more. It's the best I can do.

Here is my desired outcome, actual programming and form/fit concerns notwithstanding:

1.) Loop Jacks will be vertically stacked Neutrik or equivalent:

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2.) Like the PXL4, user has access to 16 total presets.

3.) Mute switch functions like it does on the PXL4/8 series: One press and release activates the tuner out/signal still live, two presses mutes the entire signal, press and hold for 2 seconds activates programming mode

4.) A new function for the mute switch will be that three presses switches you to "stomp mode", where all 5 footswitches get assigned to a loop for normal true bypass switching capability.

5.) Bicolor LEDs will be implemented on the Loop LEDs and Input Buffer LED. They turn blue in Stomp mode and the Input Buffer LED turns blue for the Fuzz Friendly Buffer..

6.) Trigger status works just as it would on the PXL8 series.

7.) Instead of external triggers with outputs, the Buffer section will be triggered internally to allow for presets with and without buffering to be enabled.

8.) I'd like to use the PCB mounted momentary soft switches

I've got a quick demo video and some photos of the internals to upload at some point today.

The main hurdle here is I'm a shit programmer who has never really worked with microcontrollers. I'd be willing to learn and help but I'm a brute force programmer type and I work best with already written code to modify.

On that topic, I spied this internally but I am not 100% sure what it is. I'm assuming it's some unused way to upload firmware to the unit. Could it be used in reverse?:

1678979690489.png

The end result here would be a pretty damn powerful and compact switcher, capable of coordinating a medium sized pedalboard. With 5 loops, you could accommodate a medium sized board with most of the standard 7-10 tap power supplies.
 
Definitely interested in this. Unfortunately, I can't offer much help regarding programming. It'd be great to see the develop though.

On that topic, I spied this internally but I am not 100% sure what it is. I'm assuming it's some unused way to upload firmware to the unit. Could it be used in reverse?:
Most likely not. You'd probably be able to access compiled code, but it wouldn't be readable in any meaningful way.
 
I love this idea! I'm happy to help where I can. I am a programmer, but I've never done anything embedded or with microcontrollers like this. I have built a "dumb" loop switcher, which of course has made me wish I had a smart one like this.

To my mind, most of the features you mention don't seem too hard, e.g. switchable buffers, relay switching, tuner outs, in a non-smart switch. It's the whole connecting that stuff to an MCU part that seems hard to me. But this does seem like an area Robert has some experience, so if we can harness his knowledge in the process we'd get a lot more done faster I bet.

Regarding your last pic, I wonder if that could be an I/O connection, something like JTAG. If it is possible to dump the firmware and look at it, we could use it as a guide to do a parallel reimplementation (to avoid legal issues...). But we would need to use similar hardware, which may or may not be a problem.
 
Regarding your last pic, I wonder if that could be an I/O connection, something like JTAG. If it is possible to dump the firmware and look at it, we could use it as a guide to do a parallel reimplementation (to avoid legal issues...). But we would need to use similar hardware, which may or may not be a problem.

That’s where my mind was going. The hardware is readily available, so if we could “sneak a peek” at the code, we could bend it to our will.
 
Well. I've been looking at getting a PXL8 for a while. You might have just pushed me into it, if for no other reason than to try to dump the firmware, which is something I've considered learning how to do in general as well lol. To the Reverb.com-mobile! I wonder if i can do the smaller one and the firmware would be the same.

Do you have pics of the MCU? I know there are still shortages, and the choice of MCU will be probably the most important one, in terms of availability, ease of programming, software tooling, flashing, power draw, etc.
 
BYOC has something right up this alley BUT it's been out of stock for as long as I can remember. Seems like practically speaking it's discontinued and just hasn't had the info taken down yet.

I'd be one of the first in line if PPCB had something similar. I've wanted one of these for ages but like I said has been out of stock for years now.
I also had a Disaster Area DPC-8EZ at one point and that was kind of in the same ballpark too, although part of its big draw is midi capabilities. It works okay as a semi-smart switcher on its own but really shines when paired with a midi controller. The DPC-5 is somewhat of an all-in one but less loops.
 
BYOC has something right up this alley BUT it's been out of stock for as long as I can remember. Seems like practically speaking it's discontinued and just hasn't had the info taken down yet.

I'd be one of the first in line if PPCB had something similar. I've wanted one of these for ages but like I said has been out of stock for years now.
It was in stock, with a plain drilled enclosure, late January into February at some point. I almost picked one up, but I had just gotten the Epic Looper PCB.
 
Cant help much in terms of programming, but I'll help in any way I can. I'd suggest perhaps using the smaller Fujitsu B4CA4.5 relay package instead of the large Panasonic package, especially as these are much more readily available it seems-- I can't count the number of times the TQ2-L5V has been backordered. The smaller package would mean that we could have stereo implementation as well.
Optional optocoupler muting would also be a plus, and could easily be omitted with no issues, or could be made selectable via internal dipswitches.
 
Well. I've been looking at getting a PXL8 for a while. You might have just pushed me into it, if for no other reason than to try to dump the firmware, which is something I've considered learning how to do in general as well lol. To the Reverb.com-mobile! I wonder if i can do the smaller one and the firmware would be the same.

Do you have pics of the MCU? I know there are still shortages, and the choice of MCU will be probably the most important one, in terms of availability, ease of programming, software tooling, flashing, power draw, etc.

The Joyo uses the STC 89C52RC
 
BYOC has something right up this alley BUT it's been out of stock for as long as I can remember. Seems like practically speaking it's discontinued and just hasn't had the info taken down yet.

I'd be one of the first in line if PPCB had something similar. I've wanted one of these for ages but like I said has been out of stock for years now.

That has a lot of the functionality for sure.

Adapting the core concept of what I want onto that might be more doable then trying to right all new code, etc.

Since we only need 5 loops, i'm sure we could hijack some of the extra I/O for the triggers, buffer switching, etc.
 
Even if you manage to dump/decompile the code you'll have pure Assembly language. Without a fair amount of knowledge of Assembly and the STC8501 architecture it won't be much good to you.

This isn't an extremely complicated task, it'd be much easier to just write the code from scratch.
 
Even if you manage to dump/decompile the code you'll have pure Assembly language. Without a fair amount of knowledge of Assembly and the STC8501 architecture it won't be much good to you.

This isn't an extremely complicated task, it'd be much easier to just write the code from scratch.

That's what I figure. Otherwise, why the hell would they have made it that easy?
 
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