Re: Open Source Digitally controlled Analog Project...
« Reply #20 on: March 08, 2019, 11:01:28 AM »
The problem with a project like this is defining its scopes and limitations.  ;D

The relay control approach is right for some applications, the VCA approach is right for some applications, and the Digital pot is perfect for some applications (AD5290 is the best I know of).

It might make sense to implement all of these as possible options, within a framework, and then develop it bit by bit (no pun intended)

Also, my vote is for NRNP midi.... 14 bits is enough resolution. There are enough challenges with implementing something like this in the first place, no need to reinvent the wheel......

DPOT is 8-Bits, 14-Bits is Overkill

the logic thing to do, is to use 2x CCs for 1x DPOT,
CC#        0-127 for 0~50%
CC#+1   0-127 for 51%~100%.
but that can create opposing forces.
works like a Non-RAID BIG/SPAN architecture.
https://en.wikipedia.org/wiki/Non-RAID_drive_architectures

or maybe:
CC# Pair
CC#+1 Impair,
alternating values like RAID 0. "Stripped"
but automation would be too much complicated, drawing a simple curve would be almost impossible, without a pair/impair splitter.
https://en.wikipedia.org/wiki/Standard_RAID_levels#RAID_0
https://en.wikipedia.org/wiki/Nested_RAID_levels

there are only 127 CC per Channel = 64 DPOTs or Relays per MIDI Channel, 16-Channels per MIDI Port...
but...
DMX machines use Channels for features, and CC ranges for On-Off features.
DMX Values table:
https://www.chauvetprofessional.com/wp-content/uploads/2015/07/Q-Spot_260-LED_QRG_Rev-02-1-30-12DEC.pdf
https://www.chauvetprofessional.com/wp-content/uploads/2015/07/Q-Spot_260-LED_UM_Rev-02-1-30-12DEC.pdf

DMX is a similar 8-Bit architecture.
to control multiple DMX lights, they must be split in channels...

if i have 1 machine with 8 channels, and 2 with 16 channels...
one possible DMX configuration is:
1-8 HW1
9-25 HW2
26-42 HW3.

the number of channels each machine uses is fixed, some activate or deactivate advanced mode, 8-channels basic, and 8-optional.
but the value/number of the channel group is dynamic,
and the order of the channels is continuous.

SCSI uses 1 Channel = 1 Machine.

Using same HW layer as MIDI, but different compatible protocol...
some MIDI interfaces are Not multi-client,
that means if you have Protools or Cubase or Logic, or Ableton, etc...
the MIDI interface is busy...
and cannot be shared with other softwares,
assuming the HW control software is Stand alone,
but that depends on the MIDI interface driver design...
RME hdsp 9632 MIDI interface i think is multi-client...

real midi ports are definitely better than USB Midi ports.
Lan rtpMIDI is definitely better than USB Midi ports.
« Last Edit: March 08, 2019, 11:33:46 AM by Juanpcdiy »


Re: Open Source Digitally controlled Analog Project...
« Reply #21 on: March 08, 2019, 12:13:15 PM »
DPOT is 8-Bits, 14-Bits is Overkill

the logic thing to do, is to use 2x CCs for 1x DPOT,

That's exactly what do RPN/NRPN...
+two CC to set the NRPN number

you end with 16384 parameter of 14bit (16384steps) that's what midi can do since decades (if manufacturer/developer bother to fully implement midi spec...)

Some Dpot go up to 10bit... NRPN do it easy with stepped LSB  (MSB  0 to 127 + LSB 0/15/31...111/127 ) or non full scale use of first 1024 value (MSB+LSB from 0 to 1023)

Best
Zam

iampoor1

Re: Open Source Digitally controlled Analog Project...
« Reply #22 on: March 08, 2019, 12:29:21 PM »
Yes...14 bits is overkill, but 8 bits is underkill. VCA's can have a much finer resolution than a DPOT, and Dpot resolution is surely going to improve with time. Many DPOTs go up to 10bits already. If you are trying to build a "standard" do not start with the absolute minimum resolution when implementing a 14bit interface is not much more work! :)

mhelin

Re: Open Source Digitally controlled Analog Project...
« Reply #23 on: March 08, 2019, 02:19:20 PM »
I don't understand why you still consider MIDI (vs.  OSC). OSC would be much better fit in this kind of use case which is to control analog devices. Like there's tons of software which to integrate easily. For an example check these free SW libraries:

OSC VST bridge:
http://oscvstbridge.sourceforge.net/
-VST plugin for OSC

https://github.com/CNMAT/OSC
- Arduino and Teensy OSC library

TouchOSC:
https://hexler.net/software/touchosc

Grab those, and what ever hw control mechanism (VCA, digital pots etc.) you ever want to use you can implement using Arduino or Teensy board connected to your HW and control, at least on prototyping level, using the above VST plugin. I think Ableton Live specially has good support for OSC (https://www.ableton.com/en/packs/connection-kit/ etc.). MIDI is outdated, it's OK for playing keyboards but not for much else. OSC uses similar resource based  URL's as all web applications today (which use REST API's). So the OSC API itself descibes the parameters and resources that can be controlled in cleartext format, for MIDI you need complex MIDI implementation charts and hundreds of pages of documentation telling which RPN/NRPN control which parameter on HW. Also the whole OSC ecosystem is growing all the time, for MIDI application you have to dig a lot to find anything usable.

E: The VST plugin above might not be the solution for current 64-bit DAW's but you get the idea anyway. Also regarding the datatypes the basic OSC datatypes are 32-bit fixed or floating point number for and example, or strings. There's simply no rationale in thinking how many bits to use, seven, 14 or something else, just send some numbers.

« Last Edit: March 08, 2019, 02:31:08 PM by mhelin »
Mikko

Re: Open Source Digitally controlled Analog Project...
« Reply #24 on: March 08, 2019, 10:17:31 PM »
Non-Invasive solutions already been done:
https://yostlabs.com/servo-center/

USB to Servo,
MIDI to Servo.
$100us. each.

gyraf

Re: Open Source Digitally controlled Analog Project...
« Reply #25 on: March 09, 2019, 03:19:31 AM »
Look again.

It's not the servos that present the problem (I diy'ed my first working cnc-machine around 1999), but the universal mechanic interface to pots and switches. 

You should really do a working and universal mechanical model before starting worrying about resolution and software. All that is already done, as you see from previous comments..

Jakob E.
..note to self: don't let Harman run your company..

Re: Open Source Digitally controlled Analog Project...
« Reply #26 on: March 12, 2019, 12:57:03 AM »
Non-Invasive CONS: too expensive...

The fastest Servo from Futaba BLS-276SV $180usd. + SH
GearBox to convert 90° to 360° $100usd. + SH  "but only works well with servos that can be reprogrammed."
https://www.servocity.com/bm-400-400-servo-gearbox

Cheapest Linear Servos $90usd. + SH
https://www.servocity.com/servos/linear-servos
Pro Linear Servos $300usd. + SH

Controller Board MIDI to 16-Servos $81usd. + SH "Expandable"
https://yostlabs.com/product/servocenter-midi/

to convert / digital control 16 Pots a "A Basic Analog Rack"
============= $4561usd. + SH Parts Only, more are needed, probably ~$5kusd.

The Gear Box cannot be avoided,
using a slower / cheaper servo can also work.

Slowest Standard Size Futaba S9151 Servo: $90usd. + SH
x16 = $1440usd. + SH
+ 16x Gearbox = $1600usd + SH
+ MIDI Controller
======== $ 3121usd. + SH for 16-pots.

Speed & Accuracy is important with multiplier Gearbox.

purchasing fake Futaba, saves cost, but are Not as accurate, they shake like Parkinson, some ACME brands are very good.
Futaba cost is prohibitive...
there are others more "price / performance" balanced ratio,
Fastest to Slowest:
Futaba BLS-276SV $180usd. + SH https://www.servocity.com/bls-276sv-servo
Futaba S9254 Servo $110usd + SH https://www.servocity.com/s9254-servo
Futaba S9452 Servo $85usd + SH https://www.servocity.com/s9452-servo
Futaba S9151 Servo: $90usd. + SH https://www.servocity.com/s9151-servo

Savox are way cheaper, $32usd, the slowest $65usd. the fastest.
https://www.servocity.com/sc1258tg-standard-size-coreless-digital-servo
Speed, Accuracy, Repeatability & Reprogramable is Unknown.

Hitec servos, depends, can be cheaper than futaba or more expensive.
some do Not work with Standard PWM signals...
Quote
The PWM range for this servo is 760 ~ 1020 usec. It will not work with servo controllers that transmit a standard PWM range (1050-1950usec). Hz Refresh rate: 200~560 Hz.
like the: https://www.servocity.com/hsg-8315bh-servo

The slowest Standard size servo from Hitec $60usd. + SH
https://www.servocity.com/hs-645mg-servo

Some have Back flow current, that requires a PAD in the circuit:
Quote
PLEASE NOTE: While compatible with most radio control devices, the regenerative braking feature of the HSB-93XX series servos may cause a problem if the device cannot accept a backflow of current. The types of devices that cannot accept this backflow are: Voltage Regulators, Power Safe Receivers and certain BEC circuits whether stand alone or integrated within an Electronic Speed Control. Check with the manufacturer or the Hitec website for a list of compatible models. If your device cannot accept a current backflow, then you must install a PAD (Power Absorbing Device - Hitec PN# 55756) as described in the manual. A PAD is included with every Hitec brushless servo.
like: https://www.servocity.com/hsb-9360th-servo
$210usd. + SH

https://www.servocity.com/hs-7940th-servo
$150usd. + SH

while its a nice idea, it becomes price prohibitive / too expensive..
PROS:
 can be purchased piece by piece, upgraded piece by piece, a big investment to start is Not required.
Different kinds of servos can be mixed, some are more important / critical than others.
Input & Output gains speed is usually Not important, but precision is.

to be continued=?...
« Last Edit: March 12, 2019, 01:44:06 AM by Juanpcdiy »

Re: Open Source Digitally controlled Analog Project...
« Reply #27 on: March 12, 2019, 09:59:20 AM »
Standard PWM signals...

Hello

Did you ever try to install a PWMed motor in an audio device ?
You'll have issue with noise...

Best
Zam

Re: Open Source Digitally controlled Analog Project...
« Reply #28 on: March 12, 2019, 10:13:36 AM »
Hello

Did you ever try to install a PWMed motor in an audio device ?
You'll have issue with noise...

Best
Zam

Non-Invasive = Outside the Box,
the Box is usually metallic / electric conductive.
the Box is usually connected to Ground.
= https://en.wikipedia.org/wiki/Faraday_cage

dirtyhanfri

Re: Open Source Digitally controlled Analog Project...
« Reply #29 on: March 14, 2019, 03:45:57 PM »
Even being out of the box, it doesn’t seem the most efficient solution.

I think Wes Audio has a nice solution for this, they even adapted it to a classic design as the 1176 compressor.

Wes Audio protocol is kind of open, I don’t recall the exact conditions but I got some tech documents easily.

I think RJ45 or even wireless is the way to go if we’ll deal just with control signals and keep audio analog. WiFi or Bluetooth antennas are cheaper than cool vu meters nowadays.

I have some clear ideas about where would I go with this, just need time to study...
Working on it...


taczowbes

Re: Open Source Digitally controlled Analog Project...
« Reply #30 on: March 18, 2019, 01:22:28 AM »
Perhaps the best way of looking at this is to think of the software implementation as one cohesive standard that could then suit various hardware control systems from various makers and manufacturers.
These systems have become more and more popular over the years and having a standard for them wouldn't be unprecedented. If we could supply an open software standard and create a few hardware implementations (some more invasive than others, some which could be built in to hardware at the design stage, etc) people might find a total recall system worth it.


 

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