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  #1  
Old 10-27-2013, 04:14 PM
Junowho Junowho is offline
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Default UMR2 with Sequential Prophet 5 rev 2

Hi, I'm thinking that midifying the prophet with the UMR2 would work.. Is this an active high select matrix? Any experience anyone?

Many thanks
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  #2  
Old 10-28-2013, 03:48 PM
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Hi Junowho, welcome to the forum.

Yes, this does look like active-high select signals on DXn with data on DYn.
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  #3  
Old 10-29-2013, 08:45 PM
Junowho Junowho is offline
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Hi John, many thanks for kind welcome! I will let know when it works!
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  #4  
Old 12-13-2014, 07:58 AM
Junowho Junowho is offline
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It works well, was hard to install though, my tech needed to improve with the keyboard connector and external switches - but the result is great!
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  #5  
Old 12-27-2014, 08:22 PM
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Quote:
Originally Posted by Junowho View Post
It works well, was hard to install though, my tech needed to improve with the keyboard connector and external switches - but the result is great!
Awesome to hear it!
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  #6  
Old 05-15-2015, 04:16 AM
willstring willstring is offline
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Hey there,

I'm also trying to install the UMR2 on the Prophet 5. Does anyone else have any input on this? Are we for sure that this is active high select? And does the Prophet 5 have suitable power rails?

Junowho-- what exactly did your tech have to improve? What was it doing wrong before you gave it to your tech? Or did he just tidy up the wiring/connectors?

Thanks in advance!
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  #7  
Old 06-03-2015, 10:45 PM
willstring willstring is offline
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Default Active high select measurement

Hey All,

I'm trying to determine whether or not my keyboard (Prophet 5 Rev3) is an active high or active low select so I don't fry the thing

All the schematics and wiring point towards it being active high select but I would like to verify this with an oscilloscope before doing anything. How exactly do I attach the oscilloscope probes to take this measurement? The oscilloscope has 2 probes (red+ and black-), do I just attach the red probe to what I believe is the select line, and the black probe to ground somewhere? How do I know where this (ground) is?

Also, what are typical frequencies and duty cycles (~50%?) of the select pulses? Does this matter if the generated pulses of the UMR2 don't match these exactly?

Thanks in advance
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  #8  
Old 06-04-2015, 09:54 PM
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Quote:
Originally Posted by willstring View Post
Hey All,

I'm trying to determine whether or not my keyboard (Prophet 5 Rev3) is an active high or active low select so I don't fry the thing

All the schematics and wiring point towards it being active high select but I would like to verify this with an oscilloscope before doing anything. How exactly do I attach the oscilloscope probes to take this measurement? The oscilloscope has 2 probes (red+ and black-), do I just attach the red probe to what I believe is the select line, and the black probe to ground somewhere?
Basically, yes.

Quote:
How do I know where this (ground) is?
You'll have to find some point on the board that is known to be ground. If there's a silkscreen, it's probably labeled somewhere. Ground traces are certain to be very common on the board.

Quote:
Also, what are typical frequencies and duty cycles (~50%?) of the select pulses?
The duty cycle will be low, since none of the select pulses should overlap each other. In other words, if you have 10 select signals, the average duty cycle won't be more than 10%.

The duty cycle might be much lower, since it doesn't take much time to sample the data lines.

Quote:
Does this matter if the generated pulses of the UMR2 don't match these exactly?
Not quite sure what you are asking here. Could you expand on your question?

The UMR2 will automatically generate data pulses in sync with the select pulses of the host.
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  #9  
Old 06-05-2015, 02:57 AM
willstring willstring is offline
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Got it, thanks, I think I was just misunderstanding how the UMR2 worked.

Here is the schematic, is there somewhere on there that clearly stands out as a ground reference pt to attach the black probe? Are those just the upside down triangles? Sorry for the stupid questions



Thanks again!

Last edited by willstring; 06-05-2015 at 03:11 AM.
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  #10  
Old 06-05-2015, 07:37 AM
willstring willstring is offline
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Nevermind the previous post, I opened the board up and it is absolutely obvious where the grounds are (little posts sticking up clearly for maintenance/calibration/quality control, several of them all connected electronically)

thanks again! oscilloscope measurements to come!
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  #11  
Old 06-05-2015, 06:10 PM
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You can also verify it using the schematic. There are lots of ground symbols on the image you have posted.

See "Voltage Nodes" on this page:

https://learn.sparkfun.com/tutorials...ad-a-schematic
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  #12  
Old 06-05-2015, 06:23 PM
willstring willstring is offline
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Thanks John, sorry for all of the silly questions.

Here's another question. Is it best to power the UMR2 directly from the main power supply? I.e., try to find a spot where the voltage is between 3-6V DC on the main supply?

Or could I just find anywhere on the Prophet circuit board where there is 5V DC? It looks like there are several spots on the schematic.

Put another way, could the choice of where I pull the 3-6V DC from on the Prophet affect the host keyboards functionality? (i'm guessing if I use the main supply it should be fine, but it might be slightly easier to wire to one of the 5V posts.)

Thanks again! I'll post pics when this is up and running
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  #13  
Old 06-06-2015, 04:33 PM
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Quote:
Originally Posted by willstring View Post
Thanks John, sorry for all of the silly questions.

Here's another question. Is it best to power the UMR2 directly from the main power supply? I.e., try to find a spot where the voltage is between 3-6V DC on the main supply?

Or could I just find anywhere on the Prophet circuit board where there is 5V DC? It looks like there are several spots on the schematic.

Put another way, could the choice of where I pull the 3-6V DC from on the Prophet affect the host keyboards functionality? (i'm guessing if I use the main supply it should be fine, but it might be slightly easier to wire to one of the 5V posts.)
As long as the spot you pick is the 5 V supply rail (as indicated on the schematic) and not simply a trace that happens to measure 5V, you should be ok.

Simply picking a spot on the PCB that measures 5 V could be bad because 1) it might be a logic (or analog) signal that changes during operation, and only happens to be 5V when you're measuring, or 2) might have a high source impedance that makes it unsuitable for powering the UMR2.

Assuming it's convenient, I'd take the 5V (and the ground, actually) from where it connects to the keyboard decoder IC. That will reduce the size of the current loop thru the UMR2 to the switch matrix signals.
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  #14  
Old 06-11-2015, 11:19 PM
willstring willstring is offline
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Alright, it looks like it is close to working.

I have located the 5V rails and the UMR2 powers on when the synth turns on, and the self test lights come on as they should.

I've attached wires to the UMR2 select and data lines and spliced them into the Prophets select and data lines, and have performed the setup procedure.

It is now responding to MIDI data, but not correctly. When I finish the setup procedure and turn the synth back on, there appear to be 2 issues when attempting to control the prophet via external MIDI:

1) The notes play backwards in groups of 8; for example, if I play the whole keyboard starting from low C, the notes actually sounding are (G Gb F E Eb D Db C) then (Eb D Db C B Bb A Ab)... and so on. I was very careful to play the chromatic scale correctly upod the 'learning' procedure and have tried several times with the same result

2) Not all of the notes sound; and it is different after every attempt at the setup procedure. I think once I got all but 1 note sounding but usually 1-2 notes in every octave don't work.

Does this ring a bell? Perhaps the setup procedure isn't working correctly? I've tried about 10 times and am nearly certain i'm doing it exactly as the manual states. Any thoughts?
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  #15  
Old 06-12-2015, 12:00 PM
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Quote:
Originally Posted by willstring View Post
Alright, it looks like it is close to working.

I have located the 5V rails and the UMR2 powers on when the synth turns on, and the self test lights come on as they should.

I've attached wires to the UMR2 select and data lines and spliced them into the Prophets select and data lines, and have performed the setup procedure.

It is now responding to MIDI data, but not correctly. When I finish the setup procedure and turn the synth back on, there appear to be 2 issues when attempting to control the prophet via external MIDI:

1) The notes play backwards in groups of 8; for example, if I play the whole keyboard starting from low C, the notes actually sounding are (G Gb F E Eb D Db C) then (Eb D Db C B Bb A Ab)... and so on. I was very careful to play the chromatic scale correctly upod the 'learning' procedure and have tried several times with the same result

2) Not all of the notes sound; and it is different after every attempt at the setup procedure. I think once I got all but 1 note sounding but usually 1-2 notes in every octave don't work.

Does this ring a bell? Perhaps the setup procedure isn't working correctly? I've tried about 10 times and am nearly certain i'm doing it exactly as the manual states. Any thoughts?
Well, I guess the good news is that you're getting some results. I'm not sure yet what might be causing the trouble.

Have you tried reducing the install to just a few keys? For example, connect only the data lines and a single select line. Then perform the setup procedure for only the related keyboard keys? This can help to provide some insight into the problem. (If one select line works OK, then try adding a second one and repeating the setup procedure, etc.)

Or, what about trying a single data line but all of the select lines?
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  #16  
Old 07-05-2015, 10:03 PM
willstring willstring is offline
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Got it working!

I had the intermediate connectors reverse :/

Everything works perfectly now! Thanks so much for the help!
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  #17  
Old 07-20-2015, 08:20 AM
willstring willstring is offline
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Actually in looking at it a bit closer it looks like there is still a problem.

When I press any of the notes on Data 4 (every 8th note on the prophet starting on the low Eb), they come out sounding glitchy & erroneous. The note pitches however come out correctly.

I'm basically using a 3 way splitter that I made with project PCB and 3 female DIP sockets to splice the UMR2 into the prophet's data/select lines. I triple checked for shorts in the whole circuit and everything came out okay. I also tried swapping the data 4 wire going into the UMR2 with another wire, and repeating the setup procedure. This did not eliminate the problem, and it occurred on the same notes.

When I play the notes on the prophet (with MIDI still connected), there is no issue.

Any thoughts? I tried cleaning the contacts on all of the keys to make sure they making good electrical contact during the setup procedure.
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  #18  
Old 07-21-2015, 07:56 PM
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Quote:
Originally Posted by willstring View Post
Actually in looking at it a bit closer it looks like there is still a problem.

When I press any of the notes on Data 4 (every 8th note on the prophet starting on the low Eb), they come out sounding glitchy & erroneous. The note pitches however come out correctly.

I'm basically using a 3 way splitter that I made with project PCB and 3 female DIP sockets to splice the UMR2 into the prophet's data/select lines. I triple checked for shorts in the whole circuit and everything came out okay. I also tried swapping the data 4 wire going into the UMR2 with another wire, and repeating the setup procedure. This did not eliminate the problem, and it occurred on the same notes.

When I play the notes on the prophet (with MIDI still connected), there is no issue.

Any thoughts? I tried cleaning the contacts on all of the keys to make sure they making good electrical contact during the setup procedure.
There is a chance that the host circuitry reads the keyswitch states so quickly that the UMR2 does not always have a chance to inject the "faked" key data in time. This could result in glitchy notes, since the UMR2 might be successful on most, but not all, read cycles.

If that is the case, there probably isn't a solution. However, it's not entirely logical that such a problem would be observed on a single data line.

My understanding from your description is that the same notes are glitchy, whether the associated data line happens to be connected to UMR2 data 4, or UMR2 data 3, 2, 1, etc. Correct?
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  #19  
Old 07-22-2015, 12:46 AM
willstring willstring is offline
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Hey John,

Thanks for the response. Yes, it only happens on notes associated on the host data 4, regardless of what solder posts they are connected to on the UMR (I've only tried it for one other solder post though). All of the other lines work absolutely perfectly, with no glitches.

In my case, since the prophet starts on a low C, this means that the low Eb is glitchy, along with every 8th note after that (i.e., Eb1, B1,G2,Eb3,B3,.... etc).

It doesn't make sense to my why it would work on all the other data lines correctly. When performing the setup procedure, does it matter how long I hold the note on the host keyboard? I usually just press it fairly quickly (say, an eighth note at 100 bpm).

Do you have any recommended paths forward to troubleshoot? I think there might be a few more things I can try on my end but i'm starting to run out of ideas.
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  #20  
Old 07-23-2015, 11:40 AM
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Quote:
Originally Posted by willstring View Post
Hey John,

Thanks for the response. Yes, it only happens on notes associated on the host data 4, regardless of what solder posts they are connected to on the UMR (I've only tried it for one other solder post though). All of the other lines work absolutely perfectly, with no glitches.

In my case, since the prophet starts on a low C, this means that the low Eb is glitchy, along with every 8th note after that (i.e., Eb1, B1,G2,Eb3,B3,.... etc).

It doesn't make sense to my why it would work on all the other data lines correctly. When performing the setup procedure, does it matter how long I hold the note on the host keyboard? I usually just press it fairly quickly (say, an eighth note at 100 bpm).
This is fine. The exact note duration during setup does not matter. The fact that you're getting correct notes (glitchy or not) means that the setup procedure worked correctly.

Quote:
Do you have any recommended paths forward to troubleshoot? I think there might be a few more things I can try on my end but i'm starting to run out of ideas.
Here's one last idea.

You might try removing the host's 22k pull-down resistor on the offending data line. The pull-down resistors are part RA202 in your schematic. I'm guessing you can do this by just disconnecting a single pin that connects RA202 to Data 4.

The theory:

The UMR2 has its own 15k pull-down resistors, which means that, when the UMR2 is connected to the host, the pull-down resistance on each data line is cut to ~9k.

A smaller pull-down resistance means a slower low-to-high transition on the data bus, since the voltage takes longer (like, microseconds or less) to rise from 0V to 5V.

Maybe the signal on that particular data line is not reaching a logic "1" quite fast enough on some reads. (Maybe that line has a slightly higher capacitance than the rest, for an unknown reason.)

Removing the host's pull-down brings the total pull-down value back up to 15k and should make the low-to-high transition slightly faster.

*Make your changes non-permanent, because the pull-downs are required if you decide to remove the UMR2.

If that doesn't work, I'm not sure what else to try. It might be helpful to study the signals with an oscilloscope.
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