Select Bus

From circuitbending to homebrew stompboxes & synths, keep the DIY spirit alive!

Moderators: Kent, Joe., luketeaford, lisa

User avatar
Sandrine
Super Deluxe Wiggler
Posts: 2288
Joined: Tue Jun 09, 2015 10:28 pm
Location: BC Canada
Contact:

Select Bus

Post by Sandrine » Wed Nov 06, 2019 2:37 pm

I just did a search in DIY and was surprised to discover there's no Select Bus topic
I have been working the the dev. of two modules and each will have the Select bus (CV bus) capability. This newish system rides MIDI signals on the old CV line of the 16 pin PSU bus. A growing number of modules seem to be adapting S-Bus for selecting presets in several modules from a single master module (mostly)
The only master for generic selection is the storage strip, which also sets modules to store parameter presets which greatly eases setting up a patch.

Anyway, blah blah blah, the Storage strip seems to be no longer available so I have been forced to make my own to test the upcoming modules with. It was super simple so I'm amazed no-one else has done this

Here's my not-too-well-thought-out module:

[video][/video]

Any thoughts on a new for 2020 Select bus storage strip-like module?

User avatar
Buttons ARE toys
Wiggling with Experience
Posts: 408
Joined: Wed Sep 14, 2016 9:24 am
Location: Earth

Re: Select Bus

Post by Buttons ARE toys » Fri Dec 27, 2019 11:40 am

I for one would love to see this thing become a reality! I've been getting more and more interested in the select bus as a way to reduce the amount of time needed to work with my modular.
Astronomical Dusk - a web radio show of synthetic delights and collected oddities. Airs monthly at astronomical dusk.

User avatar
MvK
Wiggling with Experience
Posts: 471
Joined: Mon Nov 24, 2014 8:46 am
Location: Berlin

Re: Select Bus

Post by MvK » Fri Dec 27, 2019 1:00 pm

would be an instant buy for me. Am I right in assuming that this would work with die Mungo enterprise modules? They also can switch and store presets via midi over 16pin.

User avatar
pld
Super Deluxe Wiggler
Posts: 1001
Joined: Thu Mar 05, 2015 5:15 am
Location: Germany
Contact:

Re: Select Bus

Post by pld » Fri Dec 27, 2019 2:23 pm

Nice. It is a bit surprising there isn't a DIY implementation yet given that the spec has been floating around for a while.
Like I2C it's the kind of thing that piques my interest, but so far no modules that would respond have ended up in my rack...

User avatar
jameswalk
Common Wiggler
Posts: 174
Joined: Thu Feb 21, 2013 1:13 pm

Re: Select Bus

Post by jameswalk » Thu Apr 16, 2020 3:20 am

Just stumbled across this. Absolutely what I’m looking for to save multiple select bus module states (mungo stuff plus/omnimod). I’m not diy inclined really but maybe would give it a go or pay someone else to do so. I would buy a production model in a heart beat.

User avatar
Sandrine
Super Deluxe Wiggler
Posts: 2288
Joined: Tue Jun 09, 2015 10:28 pm
Location: BC Canada
Contact:

Re: Select Bus

Post by Sandrine » Thu Apr 16, 2020 9:51 am

jameswalk wrote:
Thu Apr 16, 2020 3:20 am
Just stumbled across this. Absolutely what I’m looking for to save multiple select bus module states (mungo stuff plus/omnimod). I’m not diy inclined really but maybe would give it a go or pay someone else to do so. I would buy a production model in a heart beat.
It wouldn't need to be be DIY ;)
It would have a display of some kind as I can see a lot of possibilities as both master & slave. It would also be slightly more HP of course, perhaps the same format as the Accord Melisma with an encoder and more buttons, so stuff can have names. That's my biggest issue is remembering which preset does what
Also taking some initiative (like with the Melisma's root note/chord control) to add some other controls to the protocol, perhaps other manufacturers would follow suit

User avatar
EATyourGUITAR
has no life
Posts: 5798
Joined: Tue Aug 31, 2010 12:24 am
Location: Providence, RI, USA

Re: Select Bus

Post by EATyourGUITAR » Thu Apr 16, 2020 10:33 am

maybe we should start putting CAN BUS on modules? SPI would be too complicated to standardize across all manufacturers or larger systems. CAN BUS seems like the perfect protocol. modbus or simply RS-485 would be my second choice. CAN is probably the best since you can use low speed serial in almost any network topology.
WWW.EATYOURGUITAR.COM <---- MY DIY STUFF

User avatar
jameswalk
Common Wiggler
Posts: 174
Joined: Thu Feb 21, 2013 1:13 pm

Re: Select Bus

Post by jameswalk » Thu Apr 16, 2020 11:04 am

Sandrine wrote:
Thu Apr 16, 2020 9:51 am
jameswalk wrote:
Thu Apr 16, 2020 3:20 am
Just stumbled across this. Absolutely what I’m looking for to save multiple select bus module states (mungo stuff plus/omnimod). I’m not diy inclined really but maybe would give it a go or pay someone else to do so. I would buy a production model in a heart beat.
It wouldn't need to be be DIY ;)
It would have a display of some kind as I can see a lot of possibilities as both master & slave. It would also be slightly more HP of course, perhaps the same format as the Accord Melisma with an encoder and more buttons, so stuff can have names. That's my biggest issue is remembering which preset does what
Also taking some initiative (like with the Melisma's root note/chord control) to add some other controls to the protocol, perhaps other manufacturers would follow suit
Amazing!! For what its worth I'm mixed on a screen, with that nice LED grid - having it at 4hp seems a dream. That said, if you could somehow wrap in further use cases or functionality like i2c state recall (monome/mannequins/orthogonal devices/intellijel etc) then this could be a kind of matrix mixer for sequencing or morphing through saved states across various protocols (wowow). Also the ability to assign and bypass certain modules would be brilliant, as it would allow effects modules to potentially trail through unaffected by a global state change.

In anycase, I'm already onboard and love it that finally someone is taking select bus control seriously. Great job.

User avatar
pld
Super Deluxe Wiggler
Posts: 1001
Joined: Thu Mar 05, 2015 5:15 am
Location: Germany
Contact:

Re: Select Bus

Post by pld » Thu Apr 16, 2020 11:18 am

EATyourGUITAR wrote:
Thu Apr 16, 2020 10:33 am
maybe we should start putting CAN BUS on modules?
Yeah, CAN does seem like a good choice. IIRC there was already someone who did that a while back... Artisan Electronics maybe? Vaguely I remember it also being essentially MIDI over CAN but might be mistaken.

User avatar
Sandrine
Super Deluxe Wiggler
Posts: 2288
Joined: Tue Jun 09, 2015 10:28 pm
Location: BC Canada
Contact:

Re: Select Bus

Post by Sandrine » Thu Apr 16, 2020 11:20 am

cheers for the boost!
Possibly changing out the giant 5 pin din's for a pair of TRS jacks would allow for more buttons. It needs more buttons

Studioalethea
Wiggling with Experience
Posts: 313
Joined: Mon Dec 23, 2019 2:20 am
Location: Seattle

Re: Select Bus

Post by Studioalethea » Thu Apr 16, 2020 12:01 pm

Just confirming a bit of a newbie question: the "Select Bus" is both the CV and GATE pins of the 16-pin connector right? OR is it just one of them? OR am I off base.

I have been experimenting a lot with these lately, be in more mechanical interaction and less flexible. I have worked up a dip-switched bus board that can turn on/off the CV and Gate pins in pairs for normalized connections between modules. And I'm trying to finish up my prototyping board changes that have a couple connection pads to the bus. I like what you're doing!

User avatar
IntervoxOptima
Common Wiggler
Posts: 171
Joined: Tue Sep 16, 2014 1:02 am
Location: Tonawanda, NY

Re: Select Bus

Post by IntervoxOptima » Sat May 23, 2020 7:47 am

If this becomes a reality my newly acquired Omnimod would be ever so grateful to you! I’ll keep an eye on this discussion :cloud: :cloud: :cloud:

User avatar
Graham Hinton
Super Deluxe Wiggler
Posts: 3318
Joined: Fri Jul 02, 2010 6:28 pm
Location: England
Contact:

Re: Select Bus

Post by Graham Hinton » Sat May 23, 2020 11:08 am

Studioalethea wrote:
Thu Apr 16, 2020 12:01 pm
Just confirming a bit of a newbie question: the "Select Bus" is both the CV and GATE pins of the 16-pin connector right? OR is it just one of them? OR am I off base.
It is 3.3V level serial data on the CV bus. It's really MIDI without the features that made it so successful. Introducing an unscreened digital communication method that conflicts with other usage of a non-impedance controlled path comprising random pcbs and cables weaving around an unscreened analogue system doesn't win anyone any Brownie points. This really is a square wheel.

If you are going to use MIDI why not just use it properly? Is it a ploy because someone wants to sell adapter modules?

A MIDI port is cheap and easy to implement and it's not a bus, as it is often incorrectly called, it is a point to point system. I have several modules with MIDI ports using 3-pin 0.1" headers on the pcb. They may be connected with STP cable to panel connectors or directly between modules away from the power distribution. It works with all MIDI diagnostic tools. Why do it any differently?

User avatar
EATyourGUITAR
has no life
Posts: 5798
Joined: Tue Aug 31, 2010 12:24 am
Location: Providence, RI, USA

Re: Select Bus

Post by EATyourGUITAR » Sat May 23, 2020 11:25 am

CAN bus over CAT6 RJ45 is totally shielded. I would advocate for rj45 on the back side of a module. those allen bradley cat6 patch cables are super girthy presumably from better shielding. there are plenty of debugging tools for CAN bus. PCI 1.0 over USB cable would be a super cheap way to get a shielded cable in there but that would be more of a proprietary thing you would need to develop more. you can also use I2C over USB cable if you make it all proprietary.
WWW.EATYOURGUITAR.COM <---- MY DIY STUFF

User avatar
Graham Hinton
Super Deluxe Wiggler
Posts: 3318
Joined: Fri Jul 02, 2010 6:28 pm
Location: England
Contact:

Re: Select Bus

Post by Graham Hinton » Sat May 23, 2020 1:40 pm

EATyourGUITAR wrote:
Sat May 23, 2020 11:25 am
CAN bus over CAT6 RJ45 is totally shielded.
How many CAN bus products have you developed?

User avatar
EATyourGUITAR
has no life
Posts: 5798
Joined: Tue Aug 31, 2010 12:24 am
Location: Providence, RI, USA

Re: Select Bus

Post by EATyourGUITAR » Sat May 23, 2020 5:46 pm

I have not developed any commercial products that use CAN bus but I do know how to use the CAN bus and I am super knowledgeable in cat5 cat5e cat6 and all the layers of the OSI model built on top of that. This covers everything from the internet at the application level all the way down to the microcontroller down to assembler and even gate design.
WWW.EATYOURGUITAR.COM <---- MY DIY STUFF

User avatar
Graham Hinton
Super Deluxe Wiggler
Posts: 3318
Joined: Fri Jul 02, 2010 6:28 pm
Location: England
Contact:

Re: Select Bus

Post by Graham Hinton » Sat May 23, 2020 6:39 pm

EATyourGUITAR wrote:
Sat May 23, 2020 5:46 pm
I have not developed any commercial products that use CAN bus
If you had you would not be proposing it.
but I do know how to use the CAN bus and I am super knowledgeable in cat5 cat5e cat6 and all the layers of the OSI model built on top of that. This covers everything from the internet at the application level all the way down to the microcontroller down to assembler and even gate design.
In other words approaching the first peak of the Dunning-Kruger curve.

User avatar
EATyourGUITAR
has no life
Posts: 5798
Joined: Tue Aug 31, 2010 12:24 am
Location: Providence, RI, USA

Re: Select Bus

Post by EATyourGUITAR » Sat May 23, 2020 6:51 pm

I know that it is not an easy protocol if you are the one writing the drivers. I have a background in networking. You are more in my area than I am in yours. If people can't figure it out that is not my problem. I know that there are many layers of protocols before we even start talking about CAN bus. CAN bus is application level. After 23 years using cat5 and debugging at every level, I have my reasons why I think CAN bus is great. There is a lot of robustness in the protocols and media that CAN bus is built on top of. At work we used those Allen Bradley cables to run 200ft in the harshest conditions next to 3 phase robotics weighing over 1000lbs. We had unshielded 0v 24v digital signals (AC) directly parallel in the same cable pull to the cat6 cables. These links are self healing and error correcting but we never had problems in the first place so that was just an extra margin of safety and robustness.
WWW.EATYOURGUITAR.COM <---- MY DIY STUFF

User avatar
EATyourGUITAR
has no life
Posts: 5798
Joined: Tue Aug 31, 2010 12:24 am
Location: Providence, RI, USA

Re: Select Bus

Post by EATyourGUITAR » Sat May 23, 2020 6:54 pm

Also, you can use passive hubs, or active switching. Flexibility is built into that at the link layer. If people starting using the cheapest option it would be a passive shared Ethernet bus.
WWW.EATYOURGUITAR.COM <---- MY DIY STUFF

User avatar
emmaker
Veteran Wiggler
Posts: 705
Joined: Sat Mar 10, 2012 5:07 pm
Location: PDX

Re: Select Bus

Post by emmaker » Sat May 23, 2020 7:08 pm

EATyourGUITAR wrote:
Thu Apr 16, 2020 10:33 am
maybe we should start putting CAN BUS on modules? SPI would be too complicated to standardize across all manufacturers or larger systems. CAN BUS seems like the perfect protocol. modbus or simply RS-485 would be my second choice. CAN is probably the best since you can use low speed serial in almost any network topology.
A lot depends on what you want to do and how you want to do it. And I wouldn't recommend amateurs or people without bus decode tools that know how to use them. Bus issues can be very difficult and time consuming to resolve when you get multiple devices on the bus.

I also don't know how MIDI 2.0 or USB would fit into this. Most mid to high level ARM chips have USB built into them so it might be practical.

If you have a true master/slave situation and no one is talking out of turn I would go with I2C over a LVDS interface (they make chips to do this). While it's not as fast as SPI or CAN FD it's faster than MIDI. Biggest issue is that a lot of chips have hard wired or user programmable addresses in them. Sometimes there is no way to get device addresses that don't conflict. But if you're talking uC to uC communication you can program the addresses yourself. For debugging to I2C is a much easier bus to understand and debug tools I think are cheaper.

SPI would be better but it doesn't have any form of address/device selection or data protocol built into it. So you'd have to provide some selection with a select line or the data protocol. So as mentioned before you'd have to develop a data protocol which wouldn't be an easy task.

Guess CAN would come in second for me (CAN FD would be better but can be complicated when doing dual rates). There are bus interface chips for it so that is taken care of. CAN also has bus collision stuff built into it. As mentioned I think the debug tools for CAN bus will probably cost more.

About debugging buses. I've done a lot with Tektronix oscilloscopes, Aardvark and other bus specific devices. I prefer the Tek scopes using the analog inputs and the internal bus decode over the HW specific devices (but that's $3K-$12K for 3K/4K models new). HW specific devices work in the digital realm and can tell you if there is an error but usually not where the error is. You can go over the bits and maybe see where there is a bad bit but where it is coming from can be hard to figure out. Reason I prefer the scope in analog mode is that you can glitches or level shifts that are a few millivolts which are the various devices on the bus. If you know what you're doing you can use that info to figure out what device is doing what on the bus.

Just some thoughts.
Jay S.

User avatar
EATyourGUITAR
has no life
Posts: 5798
Joined: Tue Aug 31, 2010 12:24 am
Location: Providence, RI, USA

Re: Select Bus

Post by EATyourGUITAR » Sat May 23, 2020 7:51 pm

If USB who will pay the license? Or do you only restrict module builders to use microcontrollers with an official USB licence provided with the chip.
WWW.EATYOURGUITAR.COM <---- MY DIY STUFF

User avatar
fitzgreyve
Veteran Wiggler
Posts: 512
Joined: Mon Jul 15, 2013 4:49 am
Location: UK

Re: Select Bus

Post by fitzgreyve » Sun May 24, 2020 5:44 am

I don't normally comment on this type of discussion , but I have to side with Mr Hinton on this one "Introducing an unscreened digital communication .... weaving around an unscreened analogue system" also doesn't strike me as a wise move?

Eurorack has enough "design issues" already ?

While I am more than happy to have midi only modules in my euro setup (some people think this strange as "there is no CV"!) , but I wouldn't choose to squirt unshielded digital comms (midi or otherwise) around "internally".

"just because you can, doesn't mean you should"
Under developement:
- "Muse" (nearly ready for release!)
---------------------------------------
https://fitzgreyve2.blogspot.com/

KSS
Super Deluxe Wiggler
Posts: 3672
Joined: Mon Jan 25, 2016 7:28 am

Re: Select Bus

Post by KSS » Sun May 24, 2020 7:35 am

:agree:

User avatar
Graham Hinton
Super Deluxe Wiggler
Posts: 3318
Joined: Fri Jul 02, 2010 6:28 pm
Location: England
Contact:

Re: Select Bus

Post by Graham Hinton » Sun May 24, 2020 11:28 am

EATyourGUITAR wrote:
Sat May 23, 2020 6:51 pm
I have a background in networking.
How many network products have you developed?
You are more in my area than I am in yours.
You kid yourself. Since I developed one of the first commercial LANs that outperformed the early yellow triaxial Ethernet four years before Apple had its slower LocalTalk I have probably forgotten more about networking than you will ever know.

This thread is about Select Bus. Select Bus is a small subset of MIDI that is used for preset storage and recall and as MIDI does not have a store preset message it makes non-standard use of a controller to arm a Program Change for that purpose. That's it. If modules that used it had the MIDI circuitry (a £1 opto and a few resistors) instead of using the CV bus it would be a lot more useful and you wouldn't have to buy a special module to convert it.

What does anyone want to do between two modules that can't be expressed in MIDI? It was designed for synthesizers after all.

Don't quote me clock speeds when it is real time data throughput that is important. There is no point in having a high speed protocol that does not have a guaranteed delivery time and does not allow processing on the fly. As soon as you have to buffer packets and sort them out later it's slower.

If anybody thinks that they have an answer to a real problem that their favourite bus solves the onus is on them to go away and quietly develop their solution and then come back with working examples to prove it. That's what Dave Smith did.

User avatar
emmaker
Veteran Wiggler
Posts: 705
Joined: Sat Mar 10, 2012 5:07 pm
Location: PDX

Re: Select Bus

Post by emmaker » Sun May 24, 2020 3:52 pm

EATyourGUITAR wrote:
Sat May 23, 2020 7:51 pm
If USB who will pay the license? Or do you only restrict module builders to use microcontrollers with an official USB licence provided with the chip.
It's funny, I've done code for 5 different USB products all using NXP mid-level ARM processors with USB interfaces. All were using NXPs' MCUXpresso (their version of Eclipse) core code. Nobody every mentioned anything about a license for vendor IDs. I remember a couple of them had specific IDs. Maybe it was that they were components/nodes in a closed system.

Nothing wrong with having people pick a processor with an embedded interface in it. We do that already, I view USB no different than SPI, I2C, CAN, LIN, BiSS (worst bus ever) or straight serial. Actually providing a HW module something like a Teensy (just an example) with a library for the higher levels of functionality would be good. The developer could then fill in their product specific features.

Post Reply

Return to “Music Tech DIY”