Note toggle question

[ross3117]

I'm looking at the MPA for a project that requires note toggling.

According to the current MPA firmware manual, you can toggle a logic output using Note On status messages (logic modes 02 and 13).

The gear I'm working with doesn't generate Note Off messages, but rather Note On/velocity 0 messages (as is common in a lot of MIDI gear), so I'm assuming the MPA's note toggle features won't work with my gear (effectively working the same as logic modes 00 and 11).

Given the following MPA sysex config for logic output #1:

F0 00 01 5D 01 00 02 00 00 02 01 00 02 02 00 02 03 00 13 00 00 3D 00 3E 00 3F 00 40 00 41 00 42 00 43 3F 3F 3F 3F 00 00 00 00 00 00 00 00 F7

What will happen in the current firmware when it receives a MIDI status 9n 00 message (Note On/Velocity=0)?

Will it be:

1. processed as a Note Off message (MIDI Status 8n vv) and ignored (the logic output will not be toggled/latched).

or

2. processed as a Note On message (MIDI Status 9n 00) and the logic output will be toggled/latched.

If #1, then where do I place my order and how fast does it ship?

If #2, then can I submit an urgent feature request for the next MPA firmware release to have it optionally process MIDI Status 9n 00 messages (Note On/velocity 0) as MIDI Status 8n vv (Note Off) messages (ie not toggle/latch when it receives 9n 00 midi status messages)?

Also, it would be great to be able to set separate MIDI channels for each logic output.

Thanks!

[John]

Hi Ross,

Originally Posted by ross3117

I'm looking at the MPA for a project that requires note toggling.

According to the current MPA firmware manual, you can toggle a logic output using Note On status messages (logic modes 02 and 13).

The gear I'm working with doesn't generate Note Off messages, but rather Note On/velocity 0 messages (as is common in a lot of MIDI gear), so I'm assuming the MPA's note toggle features won't work with my gear (effectively working the same as logic modes 00 and 11).

The MPA (and all HL products) identify any note-on/velocity=0 as a "note off" message. So if you want the output to toggle state with each non-zero-velocity note-on, then modes 02h & 13h should work fine.

* Note-on-velocity-zero-is-actually-note-off is part of the official MIDI spec...not just a conventional implementation.

Given the following MPA sysex config for logic output #1:

F0 00 01 5D 01 00 02 00 00 02 01 00 02 02 00 02 03 00 13 00 00 3D 00 3E 00 3F 00 40 00 41 00 42 00 43 3F 3F 3F 3F 00 00 00 00 00 00 00 00 F7

What will happen in the current firmware when it receives a MIDI status 9n 00 message (Note On/Velocity=0)?:

1. It will be processed as a Note Off message (MIDI Status 8n vv) and ignored (the logic output will not be toggled/latched).

Yes.

If #1, then where do I place my order and how fast does it ship?

http://store.highlyliquid.com/products/mpa

Next business day!

Also, it would be great to be able to set separate MIDI channels for each logic output.

Thanks for the request. Realistically, this won't be happening any time soon because of a backlog of pending firmware updates for other products. In the meantime, you can get per-output independent channel response from the MD24.

[ross3117]

Originally Posted by John

The MPA (and all HL products) identify any note-on/velocity=0 as a "note off" message. So if you want the output to toggle state with each non-zero-velocity note-on, then modes 02h & 13h should work fine.

Great news! Thanks for the prompt and informative reply John!

Originally Posted by John

* Note-on-velocity-zero-is-actually-note-off is part of the official MIDI spec...not just a conventional implementation.

No offense intended on my part, of course

One other question came up while reviewing the HL products and firmware documentation last night...

Can the logic outputs on the MPA be used with these reed relays in order to perform the same function (SPST) as the MSA-R series? (I need two relays and two potentiometers for this project, so buying both a preassembled MSA with 8 integrated relays AND an MPA is a little overkill for me if I can leverage the logic outputs on the MPA for the same function).

If so, would I need any other components to put around them to make them work electrically with the MPA? I'm thinking I should be able to use them as-is without any other components (ie resistors, capacitors, or diodes).

Like this perhaps:



Thoughts?

Thanks!

[John]

Hi Ross,

Yes, that will work fine. The relays have the protection diode built-in, which solves one concern. The other is the current sourced by the MPA thru the coil, which is also ok. (5V thru 500ohms = 10mA).

Any chance of seeing some pictures or video of the project?

[John]

One other note--you may have reasons for choosing that specific relay, but similar others are available (perhaps with inferior contact ratings) that are much cheaper...

[ross3117]

Originally Posted by John

Any chance of seeing some pictures or video of the project?

Sure thing:


Picture #1: PAD80 back panel


Picture #2: PAD80 PCBs


Picture #3: PAD80 Circuit diagram


Picture #4: Bluetooth ring on drum stick.

I'm attempting to MIDI-fy the Hold and MOD/Bend/A.T jacks on two old Roland Octapad II (Pad 80). The PEDAL functions on this unit can be configured to internally generate and transmit HOLD, MODULATION, PITCH BEND, and AFTERTOUCH information from the MIDI OUT jack, based on the state of the signal present on these two jacks, when you hit one of the pads with a drumstick. I want to be able to dynamically manipulate the state of the signal on these jacks externally via MIDI using a very cool product called the HOT HAND MIDI-EXP and an accelerometer-enabled bluetooth ring that will be attached to a drum stick.

Originally Posted by John

One other note--you may have reasons for choosing that specific relay, but similar others are available (perhaps with inferior contact ratings) that are much cheaper...

Please tell me where and which ones!

The only reason I picked the previous relay was because it seemed close to the specs and package design for the one used on the MSA-R (ie 5v SPST). I'm not an electronics expert by any stretch of the imagination, so the one I chose was a best guess. The relay only needs to emulate a standard footswitch so inferior contact ratings isn't really a concern (I don't think).

The only critical criteria for this project is converting a MIDI CC value to a signal compatible with the HOLD (SPST footswitch) and MOD (Volume pedal-10K pot, Roland models EV-5 or EV-7) jacks on the PAD80.

Thanks for your insights on this project John. It's much appreciated! If you can point me in the direction of the cheaper relays, I think I'm confident the MPA can do what I need and I'm ready to order and start soldering!!

[John]

Hi Ross,

Wow, thank you for taking the time to describe the project. Super cool!

This is the relay used in the MSA-R:

http://www.mouser.com/Search/Product...jSXpLSHQ%3D%3D

All the usual caveats about contact ratings and watching out for inrush current apply.

The relay element from the MSA-P is this:

http://www.mouser.com/ProductDetail/...cdiwET4g%3d%3d

If "signal bleed" is not a concern, the solid-state relay might be better for reliability.

[ross3117]

Thanks for the relay referral. Those look great (and I can do all 8 logic outputs on the MPA for the price of one of the previous relays I was looking at!)

One last question...

I went to the HL store to order the MPA noticed 3 different versions.

I'm not sure which version I need. Is it possible to change from one version to the next (say 10K to 100K) after the unit has been assembled?

If not, I need to do some more circuit sleuthing on my end to determine which one I need.

[John]

Originally Posted by ross3117

I'm not sure which version I need. Is it possible to change from one version to the next (say 10K to 100K) after the unit has been assembled?

Yes. The kit comes with sockets for the digipot ICs. So if you want to change values, you just have to swap digipots.

The digipot part numbers compatible with the MPA are:

MCP42010-I/P
MCP42050-I/P
MCP42100-I/P

[ross3117]

John,

Thanks for the replies and clarifications so far.

I've received my MPA and assembled it.

On to the relays now...

I came across this nifty little gem on Amazon.

Do you think it will work with the logic outputs on the MPA?

Here are some unverified specs from a user review on this product on Amazon:

Power Supply: 5V DC / 400mA (relay all ON)
Input control signal voltage:
0V - 0.5V Low stage (relay is ON)
2.5V -5V High state (relay is OFF).
Input control signal LOW state current:
2.5V: 0.1mA.
3.3V: 0.18mA.
5V: 0.35mA.
JD-VCC or VCC: Power supply input, 5V DC. (JD-VCC RELAY POWER VCC:SYSTEM VCC)
GND: Power supply ground and control signal ground.
CH_x: Control signal input, Low: relay ON, High: relay OFF.
COM / NO / NC: (C1=COM1, C2=COM2)
Control signal state low, the relay ON, COM - NO disconnected, COM - NC connected.
Control signal stage high, the relay OFF, COM - NO connected, COM - NC disconnected

Relay specs

Product image:



Relay closeup:



Schematic:

[John]

Originally Posted by ross3117

John,

Thanks for the replies and clarifications so far.

I've received my MPA and assembled it.

On to the relays now...

I came across this nifty little gem on Amazon.

Do you think it will work with the logic outputs on the MPA?

Here are some unverified specs from a user review on this product on Amazon:

Power Supply: 5V DC / 400mA (relay all ON)
Input control signal voltage:
0V - 0.5V Low stage (relay is ON)
2.5V -5V High state (relay is OFF).
Input control signal LOW state current:
2.5V: 0.1mA.
3.3V: 0.18mA.
5V: 0.35mA.
JD-VCC or VCC: Power supply input, 5V DC. (JD-VCC RELAY POWER VCC:SYSTEM VCC)
GND: Power supply ground and control signal ground.
CH_x: Control signal input, Low: relay ON, High: relay OFF.
COM / NO / NC: (C1=COM1, C2=COM2)
Control signal state low, the relay ON, COM - NO disconnected, COM - NC connected.
Control signal stage high, the relay OFF, COM - NO connected, COM - NC disconnected

Relay specs

Product image:

Attachment 271

Relay closeup:

Attachment 272

Schematic:

Attachment 273

Yes, I think that should work just fine.