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  #1  
Old 04-18-2009, 06:16 PM
mikkojay mikkojay is offline
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Default Default Configuration

Hello,
I have assembled an MPA 10k kit and I am in the process of getting it to communicate with my Novation Remote SL 25.
Please bear with me, as I am quite new to the world of midi
I created a new template and associated 4 sliders to CC 0 to 3 in order to control the wipers on each of the 4 pots. I assigned 4 switches as toggle switches to midi notes 0 to 3, as I am using these TTL outputs from the MDA board.
I was able to load the new custom template to the midi controller, but I do not see the board reacting to the specified sliders and buttons. I do however, see that when I move the pitch bend stick on the controller that the "receive" led blinks and voltage is varied on wiper 0. This is promising (at least there is some signs of life). I am wondering if the default config for these boards is as simple as:
wipers = CC 0 to 3
TTL = midi note 0 to 7

It is absolutely possible that I am missing some piece of the puzzle regarding the setup of my custom template, or who knows what.

If anyone has a suggestion as to what to look for, test, etc.. I would truly appreciate it.

Thanks, Mike
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  #2  
Old 04-18-2009, 07:55 PM
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Hi Mike,

Thanks for the detailed description.

You'll need to send a SysEx configuration command to the MPA so that it will respond to the midi messages of your choice. Details about using your computer for this purpose are here:

http://forum.highlyliquid.com/showthread.php?t=280

Once you have that set up, you'll want send a SysEx message as follows (my comments preceded by "//"):

// Fixed Header
F0 00 01 5D 01

// Pot 0 (CC 0)
00 02 00
// Pot 1 (CC 1)
00 02 01
// Pot 2 (CC 2)
00 02 02
// Pot 3 (CC 3)
00 02 03

// Logic Output Channel (from dip switch)
00

// Logic 0 (Note 0)
00 00
// Logic 1 (Note 1)
00 01
// Logic 2 (Note 2)
00 02
// Logic 3 (Note 3)
00 03
// Logic 4 (Note 4)
00 04
// Logic 5 (Note 5)
00 05
// Logic 6 (Note 6)
00 06
// Logic 7 (Note 7)
00 07

// Fixed Footer
F7

Then, make sure your DIP switch channel setting (see MPA firmware user manual) matches the output channel of your controller, and you should be ready to go.
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  #3  
Old 04-18-2009, 10:39 PM
mikkojay mikkojay is offline
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Hey thanks for the fast reply-
I have made some progress, but still have a little way to go.
I downloaded SendSX and sent your example message in its entirety like so:
F0 00 01 5D 01 00 02 00 00 02 01 00 02 02 00 02 03 00 00 00 00 01 00 02 00 03 00 04 00 05 00 06 00 07 F7

This has my sliders working! Well, sort of- the output is the inverse of what the slider position would make you think, i.e. up is less, but so far I will take it!
I ganged together all of the "A" pins to gnd, and all of the "B" pins of the pots to the 5v output on the board. I suppose I could fix that either by swapping A & B, or I can change my slider mapping to go from 127-0 vs 0-127 (actually, I just tried that and it worked!) So that is good.

I used a LM324 quad op amp as a buffer, with the outputs fed back to the negative input, and the mpa wiper hooked to the + input. I did this because I thought I might need a little more current than the mda seems to be able to handle. Is this pretty common? Anyway, my peak voltage on the slider seems to be about 3.9vdc as opposed to the 5vdc I was hoping to see. If you have any thoughts on that, I would appreciate it.

The TTL is a little bit more of a mystery at this point.
I am using 4 of the available outputs, 0 to 3. After using the config hex you gave me, I now see the message led light when I press the buttons I have mapped to midi notes 0 to 3. Please see attachment for a sample of how I have one of the buttons set up.
I have each TTL output running thru a 4.7k resistor to the base of a 3904 npn transistor. The emitter is grounded, and the collector is tied to one leg of a relay coil. The other end of the relay coil is tied to +12vdc.

I used a multimeter to try and read state changes right at the mpa board's logic outputs, but see no changes when the buttons are pressed. I tried readings on the 0-3 outputs, which are tied to transistors as described above, as well as output 4 which is not connected to anything. All read low values.

Thanks again for the help thus far- I am sure it will be humming as soon as I get things ironed out.
I am building a laser Lumia effect projector, using the sliders to vary the intensity of red, green, and violet diode lasers & using the TTL to switch between lasers since I have 7 of them in this projector. I will post some pics when I get it all going.

Thanks, Mike
Attached Images
 

Last edited by mikkojay; 04-19-2009 at 07:50 AM. Reason: accuracy
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  #4  
Old 04-18-2009, 11:02 PM
mikkojay mikkojay is offline
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Hey John,
I tried one more thing, but had no result-
I changed the hex value preceding each note number in the logic section to be 02 vs the 00 as in your example. I was hoping that this would tell the board that I wanted to use the toggle/latching mode.
Here is the whole string:
F0 00 01 5D 01 00 02 00 00 02 01 00 02 02 00 02 03 00 02 00 02 01 02 02 02 03 02 04 02 05 02 06 02 07 F7

After doing so, I noticed that pressing the midi controller buttons no longer caused the green message led to illuminate.

Since I am using these to toggle relays, I was hoping that would do the trick.

edit- as an additional test, I tried using an 01 in front of the 04 note in the hex string, and output 04 did indeed change to a logical hi of 5v. I am still however unable to achieve any button response when I try preceding note 04 with the value of 02.
As one more test, I may try disconnecting the outputs 0 to 3 to my transistors to make sure something funny isn't going on with the way I have them configured.
Thanks, Mike

Last edited by mikkojay; 04-18-2009 at 11:36 PM.
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  #5  
Old 04-19-2009, 07:27 AM
mikkojay mikkojay is offline
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Default Success!

I hooked up an LED to the TTL out so I could try a million things & "see" if any worked- you know what did the trick? Setting the velocity to a value of 1.
After doing so, I was able to watch the led toggle on & off just the way I hoped it would.
Thanks, Mike
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  #6  
Old 04-20-2009, 06:54 PM
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Quote:
Originally Posted by mikkojay View Post
I used a LM324 quad op amp as a buffer, with the outputs fed back to the negative input, and the mpa wiper hooked to the + input. I did this because I thought I might need a little more current than the mda seems to be able to handle. Is this pretty common? Anyway, my peak voltage on the slider seems to be about 3.9vdc as opposed to the 5vdc I was hoping to see. If you have any thoughts on that, I would appreciate it.
You should be able to tweak the output of the op amp circuit by adding some resistors and/or changing their values. Look for a description of "gain adjustment" for the particular circuit you're using...
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Old 04-21-2009, 02:39 AM
mikkojay mikkojay is offline
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Cool- thanks for all your help.
Here is a you tube vid of what the projector will be making.
I use the sliders to vary the intensity of the lasers and TTL to switch between different effects. It is basically lasers being shot through rotating glass.

One last question (well, maybe not THE last), is it possible to tell the board's pots to init themselves to a state of 0vdc upon power up? Mine seem to init themselves at the halfway point. Not a huge deal, but it would be helpful from a safety standpoint in my particular application.

Thanks, Mike
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  #8  
Old 04-21-2009, 02:01 PM
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Quote:
Originally Posted by mikkojay View Post
Cool- thanks for all your help.
Here is a you tube vid of what the projector will be making.
I use the sliders to vary the intensity of the lasers and TTL to switch between different effects. It is basically lasers being shot through rotating glass.

One last question (well, maybe not THE last), is it possible to tell the board's pots to init themselves to a state of 0vdc upon power up? Mine seem to init themselves at the halfway point. Not a huge deal, but it would be helpful from a safety standpoint in my particular application.

Thanks, Mike
Mike, cool video, thanks for mentioning the MIDI decoder in the description.

The digipots automatically init to the midpoint at power-up. If code were added to the MPA firmware to initialize the digipots, there would still be a moment at power-up where the outputs were at the midpoint. If this is important to you, please send me an email or private message and we will work out a firmware customization.
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  #9  
Old 04-23-2009, 05:24 AM
mikkojay mikkojay is offline
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I decided to configure one of the 8 TTL output pins to be initialized low, and tied it to a jump-wire going to pin 12 (ShDn) on each MCP42XXX. I then programmed the midi template to toggle the TTL pin using the red "Circle" button on the Novation Remote. It worked! Turn it on, nothing. Toggle the stop button, get light. Hit the stop button again, ALL outputs are sent to 0v (pot terminal "B").
That will work.
There is still a very quick "blip" of output at start up, but it is very small and not too huge of a deal. If I were using this commercially instead of as a hobby project, it would need to be overcome. An external delay circuit would work for that though, & they are required according to certain CDRH regulations anyway.

Thanks, Mike
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  #10  
Old 04-23-2009, 02:21 PM
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Quote:
Originally Posted by mikkojay View Post
I decided to configure one of the 8 TTL output pins to be initialized low, and tied it to a jump-wire going to pin 12 (ShDn) on each MCP42XXX. I then programmed the midi template to toggle the TTL pin using the red "Circle" button on the Novation Remote. It worked! Turn it on, nothing. Toggle the stop button, get light. Hit the stop button again, ALL outputs are sent to 0v (pot terminal "B").
That will work.
There is still a very quick "blip" of output at start up, but it is very small and not too huge of a deal. If I were using this commercially instead of as a hobby project, it would need to be overcome. An external delay circuit would work for that though, & they are required according to certain CDRH regulations anyway.

Thanks, Mike
Hi Mike, that sounds like a good solution. You might experiment with a pull-down resistor on the SHDN pin in order to prevent the "blip". According to the datasheet, the pin is internally pulled high--which probably is what causes the blip (when the MPA's microcontroller output is briefly in a high impedance state at power-up).
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  #11  
Old 04-27-2009, 02:05 AM
mikkojay mikkojay is offline
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Hey John,
A 1k pull-down resistor did the trick. No blip, works just right!
Thanks, Mike
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  #12  
Old 03-05-2010, 02:40 PM
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For the record, firmware version 1.4 allows for a usre-configurable power-up state for each potentiometer and logic output on the MPA.
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