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Old 01-07-2016, 10:19 PM
sagerl909 sagerl909 is offline
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Default MIDI CPU is working, need additional help

Hi, I have hooked up the MIDI CPU control terminals to pedal board. I got it playing. I would like to connect a Hammond exp100f expression pedal to it. It has 2 photo sensitive 'potentiometers', each has 3 wires. Checking them with Ohm meter gives me reading of approx. 0 - 800 ohms. Would like to use the remaining momentary switches to change programs, Octave up & down and hold.
I would appreciate your help.
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  #2  
Old 01-08-2016, 02:37 AM
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Hi,

sorry I do not have any answer for your questions.

You may try PM'ing John directly.. click his user name and then find" Send Message" to send a direct message to him.

this link may work..

http://forum.highlyliquid.com/member.php?u=2

I do know he's been very busy with a project and its taking up all his attention right now.

/Blaine

Last edited by Synthetech; 01-08-2016 at 02:59 AM.
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Old 01-09-2016, 10:26 PM
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Hi Sager, welcome to the forum. Here are a couple of links that will help get you started. Here's some theory about connecting a potentiometer to the MIDI CPU:

http://forum.highlyliquid.com/showthread.php?t=441

This thread has a sysex example for setting up the MIDI CPU input terminals for analog input:

http://forum.highlyliquid.com/showthread.php?t=439

I hope this helps.
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Old 01-10-2016, 04:47 AM
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it was the "photo sensitive 'potentiometers " that threw me off as to what information the OP was looking for..
maybe he meant simply regular pots.. but it sound more like optical encoders to me
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Old 01-12-2016, 04:49 PM
sagerl909 sagerl909 is offline
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Hi, Synthtec & John, You are right it is a Quadrature Encoder that I need help with I misspoke as 'Photosensitive potentiometer'. In doing further search, it seems the expression pedal needs 2 sets of output to effect clockwise & anti clockwise movement. I just don't know how to hook them up. Thanks for your help.
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Old 01-13-2016, 05:22 AM
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Best to get some pictures of what you are working with. What wires you mentioned, etc.

Encoders need two terminals on the CPU each. So in your case it sounds like four are needed.
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Old 01-13-2016, 03:46 PM
sagerl909 sagerl909 is offline
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It is hard to take a picture of it, since the wires are tucked between the top & bottom parts of the pedal. Here is what i can make out: there are 2 sensors ( covered with a wax like material) 3 wires come out of each, one red and one black. The third wire from each set is a silver wire (insulated) with a bare wire attached to it. They all end in a molex connector.
I connected the red and black wire across Ohm meter and on moving the pedal, I got the reading of 0 - 800 Ohms from each set. Then I connected the red and black wires of one of the sets to Cpu's #23 & #22 terminals and the white wire to the ground. The bare wire suggested that it might be the ground. I got two short tones from the sound module on moving the pedal to the extreme forward position, not the gradual increase of the voices. Looks like it is not workable, if that is the case, I will get a potentiometer (mechanical) based pedal. Thanks for your help.
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Old 01-13-2016, 05:32 PM
sagerl909 sagerl909 is offline
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HI, I also connected the encoder as outlined in John's 11/30/10' blog. It did not work.
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Old 01-15-2016, 01:21 AM
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I still not sure what you have without pics.

Optical encoders would have a need for two wires to power the lights and receivers inside of them.

So chances are you need to put 5v on the black/red wires.
Then the third wire would be your signal wire. I'm going to guess it is covered with a silver foil "shielding" and the bare wire is probably connected to ground. The shielding is to keep stray RF interference from inducing noise on the signal wire.

one optical encoder should have two light receivers and a slotted wheel between the light and the receivers.. the wheel chops up the light and the two receivers will react to the light.
The two signal wires will send a timed signal to a microprocessor (CPU) and the uP will do math/lookup table to determine which way the wheel is turning and how fast.

Really need pics or a schematic of the pedal to truly understand what it is. I tried to google info on it and come up with nothing.

Again, my GUESS is the red/black wires need 5v and the two silver wires are your signal wires that would hook up to the midi cpu.

google Optical Encoder to understand more about these devices.. they were used inside the old ball mice for early PC's.

Last edited by Synthetech; 01-15-2016 at 01:27 AM.
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Old 01-15-2016, 05:12 PM
sagerl909 sagerl909 is offline
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I took some pics and am sending them to you, hope they are clear. The black & whit wires power the light source on one side and the rest of the wires are3 on the sensor side.
Attached Images
     
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  #11  
Old 01-16-2016, 06:18 PM
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Thanks for the pics, this helps immensly..

I can now see how it works.

The encoder is wired up like this:

Red wire +5v (or more, but I doubt it)
Bare Wires are GROUND.. or your Negative.
The Black/Clear Wires are your two signal wires.


The Foil shielding around the signal wires doubles as your Ground/Negative.

Take a look at your connector and find where the Foil/Sheilding goes to a pin. That will be your negative.. it could be common with the "light" you mentioned that uses a white wire for it's positive.
Hook this negative up to the CPU's "G"
Hook the Red wire up to the CPU's Vreg/+5v

Hook the two black wires up to a matching pair of CT's on the CPU intended for use as an encoder. For example, hook them up to CT's 8 and 9. Then read register 15h for your data/value.
see the manual's Table 2.2.3-a to lookup what terminals are paired up and their matching register.

If it goes backwards, just switch the wires around on the CT's.

that should get it working...

Last edited by Synthetech; 01-16-2016 at 06:20 PM.
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  #12  
Old 01-18-2016, 05:20 PM
sagerl909 sagerl909 is offline
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There is no shielded wire, what appears like a shielding is just a twisted silvery wire covered with clear plastic. Therefore, I connected all the other wires as you suggested and connected the bare wires to ground and blacks to CTs 23 & 22 and red to the 5V. Did not work. I am at the end of the expression pedal part and I am happy with the way the pedal works and enjoy what I have, thanks for your effort.
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Old 01-21-2016, 12:56 AM
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Yes, there is shielded wires.
I see them in your pics.


It is shown in this pic of yours and pointed to with arrows.
It covers the signal and power wires on the front loom of wires and is the ground wire for power.. a commonly practiced design.

The "black" wires are actually a loom of more than one wire together.

The second loom of wires behind it also are shielded. Hard to tell if there is just a signal wire and the foil/ground or if it also has a positive/red wire like the front one.

Sorry if it didnt work. Or did it? I dont understand, "I am at the end of the expression pedal part and I am happy with the way the pedal works..."
sounds like you got it to work??
I tried to locate this part you mentioned.. "I also connected the encoder as outlined in John's 11/30/10' blog"
I couldnt find that blog or an entry with that date.

Curious what code you were trying to use and if you were reading the correct register for CTs 23 & 22..
Encoders can be tricky to get to work and it helps to hook an LED up to see if it is pulsing a signal out on each terminal to troubleshoot problems.





Last edited by Synthetech; 01-21-2016 at 01:13 AM.
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Old 01-21-2016, 07:13 PM
sagerl909 sagerl909 is offline
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Hi Synthetec, Thanks for your reply. The 2nd sensor does not have a red wire, it only has a black and a bare wire coming out of it.
At the connector end there is no other pin is connected such as the shielding.
The expression pedal is not working when I connected it as you suggested. I used the bare wires to connect to 'G'. Connected red wire to the + of the power supply of the MIDI CPU and the black wires toCT#22 & 23 each. I observed the indicator LED of the cpu as I moved the pedal, it did not light up.
Only the pedal board is working and not the Hammond EXP100F expression pedal.
I referred to John's blog: http://forum.highlyliquid.com/showthread.php?t=441
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Old 01-21-2016, 09:58 PM
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Ok..

this

http://forum.highlyliquid.com/showthread.php?t=441

is for hooking up analog potentiometers.

you have optical ENCODERs
so that info does not apply to the pedal you are trying to hook up.


The code used for encoders is totally different.


please refer to:

3.3.2 Encoder Input: Control Change (CC)


in the Firmware Manual

it mentions to use mm 14h mode and d0 is your Control Change number and d1 is the register for the pair of CT's you will use. See table
Table 2.2.3-a: Multipurpose Data Registers
when you look up 22/23 CT's in that table it say's to use register 1Ch

So code for those two CT's would be something like


F0 00 01 5D 04 01 00 //your header

then below is what your custom code for each CT would look like..
16 00 14 00 17 1C
16h is CT 22, 00 transition, 14 is encoder Control Change mode, 00 would be MIDI channel (usually one), 17 is Control Change #23 and 1C would be the data register we will monitor for value (CT's 22/23).

then do transition 01for CT 22(16h)
16 01 14 00 17 1C

and code for CT 23(17h) would be the same
17 00 14 00 17 1C
17 01 14 00 17 1C



or in one msg sent to the CPU it would be..


F0 00 01 5D 04 01 00
16 00 14 00 17 1C
16 01 14 00 17 1C
17 00 14 00 17 1C
17 01 14 00 17 1C
F7


there are a few other encoder modes you could use, but my guess is you are after Control Change and some specific CC# with a value that goes from 0-127 when you move your pedal.


and yes, hook up the bare wires to Ground, the red wire to +5v and the two clear covered wires up to CT's 22/23

if it begins to work and goes the wrong directions in value, just swap the CT's around.

hopefully this get's you going
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Old 01-22-2016, 04:35 PM
sagerl909 sagerl909 is offline
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Thanks for explaining the process. I have one question though. I read through the firmware manual and found on the table 9-3 that the CC values for CT#22 & 23 are already set to a transition values of 0-127. Do I have to change it in any way?
The blog that John referred to, if you scroll down , he has also given a configuration for optical encoder. That is the connection I followed.
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  #17  
Old 01-22-2016, 11:25 PM
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Quote:
Originally Posted by sagerl909 View Post
Thanks for explaining the process. I have one question though. I read through the firmware manual and found on the table 9-3 that the CC values for CT#22 & 23 are already set to a transition values of 0-127. Do I have to change it in any way?
I cannot find a table 9-3
the last table in the firmware manual is
Table 8.3-a: Firmware Versions

Perhaps you meant Table 4.3?

You can change the register, 1Ch for an encoder used on CT's 22 & 23, to be limited with a min/max value.
see
Figure 4.3-1: Data Register Configuration SysEx Message
look at
nn ii mn mx rr

that equates to
Register, Initial Value, Minimum Value, Maximum Value, Round Robin Enable

Dont worry about the Round Robin.. it would not apply to encoders, usually.

But say you want your pedal to only go from 2-50. You would use values like this
1C 02 02 32 00
which is
1C for the register
02 for Initial Value for the register to start at (if not set, it will default to 00 at startup)
02 for Minimum Value. It will not let you go below "2"
32 for Maximum Value. In this case Value of "50", since 32 in hex = 50 in decimal
00 for Round Robin.. we dont need it, so we dont enable it.

Hope that makes some sense....
I am not entirely sure how the MIDI CPU will handle values of your pedal if you change the appointed register's Min/Max values.
IE, I do not know if it will "STRETCH" out the Min/Max values from Pedal all the way up to Pedal all the way down.
It may just not respond until you press it down far enough to get past your first value.. then it will allow you to change values all the way up to your maximum value..
So if you max value is "64", then it may stop changing the value midway down. Then the last half of your pedal movement will be dead.
If that is so, I have no way to prevent it from doing so.. that would be something John would have to answer about..



Quote:
The blog that John referred to, if you scroll down , he has also given a configuration for optical encoder. That is the connection I followed.
if you are referring to this post

http://forum.highlyliquid.com/showpo...84&postcount=3

then that is not an encoder. It is a Photoresister. Totally different component.
It acts like a potentiometer and varies voltages when light is bright or dimmed.

Optical Encoders detect "blips" of light going thru slits on a spinning wheel.
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