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Old 05-18-2010, 05:58 PM
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John John is offline
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Default MIDI CPU New User Orientation and Basic Troubleshooting

Just received your new MIDI CPU? This post will help you "get your feet wet" before you begin your project.

Power Test

Download the MIDI CPU Hardware manual from the product page. The "Power Supply" section of the manual describes the power supply wiring. A 9V battery is an easy beginner's power source.



When you connect power, the MIDI CPU activity LED should light up for a second or two. This is the LED "self test" that is performed at each boot-up. The self-test will also occur when the MIDI CPU resets itself after you update the configuration via MIDI SysEx message. More about that in another thread.

If you want a constant power indication, you can connect an LED as described in the "Power LED Wiring" section of the hardware user manual.



Try a 1kohm resistor for RLED. As long as the resistor is in place, you can try any LED you'd like--no risk of damaging it or the MIDI CPU.

Control Terminal Test

The MIDI CPU ships with a default configuration that causes it to generate MIDI notes when the control terminals are grounded. With the MIDI CPU powered up, take a piece of wire and temporarily connect a "G" terminal with one of the control terminals. (The control terminals are marked with the numbers 0-23.)

When the wire is connected, you'll notice that the activity LED blinks briefly. This means that the MIDI CPU detected the input signal and generated a MIDI event.

We haven't connected the MIDI terminals yet--but you'll notice that the activity LED blinks once when the control terminal is grounded, and again when the wire is disconnected. That's because the MIDI CPU responds to each transition of the control terminal input--from disconnected to grounded, and back from grounded to disconnected. (We can also configure it to ignore either or both transitions--more about that in another thread.)

MIDI Wiring Test

Of course, the purpose of the MIDI CPU is to be connected to a MIDI device. The hardware user manual describes the wiring for MIDI connectors. Note that pin #2 is unconnected on the "MIDI In" terminal. Pins #1 and #3 are unused.



If there are other MIDI devices handy, we can easily test the MIDI wiring. Let's say you have a MIDI controller device (like a keyboard with a MIDI output) and sound module (with a MIDI input). Forgetting the MIDI CPU for a moment, connect the MIDI controller to the sound module and configure each so that the module is responding to the controller:

(MIDI Controller MIDI Out) -> (Sound Module MIDI In)

If that works, disconnect the two, and place the MIDI CPU in between:

(MIDI Controller MIDI Out) -> (MIDI CPU MIDI In)
(MIDI CPU MIDI Out) -> (Sound Module MIDI In)

With the MIDI CPU powered up, you should still be able to control the sound module using the MIDI controller.

The MIDI CPU takes messages from its MIDI In port and echoes them on its MIDI Out port. (This is the "MIDI merge" functionality described in the user manual.)

Note that the MIDI CPU activity LED also blinks when a MIDI message is echoed on the MIDI CPU MIDI Out port.

If the sound module responds to MIDI notes on MIDI channel 1, we can also try to control it with the MIDI CPU. In the default configuration, control terminals 0-23 generate MIDI notes, starting with "middle C". So, if a control terminal is temporarily grounded, the sound module should receive a MIDI note and generate a sound.

If a MIDI controller and sound module aren't available, you can also test the MIDI CPU MIDI I/O by using the MIDI ports on your PC.

More to come...

Last edited by John; 06-17-2010 at 07:21 PM.
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Old 12-28-2011, 08:25 PM
nobax nobax is offline
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Default Thanks so much

John

I am an organist who really only wants to play but needs to get the organ and my Roland Fantom XR communicating - so that I can change voices/patches etc from the organ. I have realised that I need to build a controller that I can populate with press-buttons to act as registration pistons that bring about different selections combinations of voices . On a theatre or church organ, these pistons are arranged in a row between keyboards (manuals).... sorry if I am telling you something you already know.

The purpose of the reply is to say a big thank you for the very beginner-friendly, concise guidance, the quality of which I had begun to despair of ever finding!

Geoff
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Old 01-03-2012, 05:05 PM
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John John is offline
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Default

Quote:
Originally Posted by nobax View Post
John

I am an organist who really only wants to play but needs to get the organ and my Roland Fantom XR communicating - so that I can change voices/patches etc from the organ. I have realised that I need to build a controller that I can populate with press-buttons to act as registration pistons that bring about different selections combinations of voices . On a theatre or church organ, these pistons are arranged in a row between keyboards (manuals).... sorry if I am telling you something you already know.

The purpose of the reply is to say a big thank you for the very beginner-friendly, concise guidance, the quality of which I had begun to despair of ever finding!

Geoff
Geoff, thank you for the kind feedback.

I hope you'll create a thread for your project and show us some pictures or a demonstration video.
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Old 01-05-2014, 09:56 AM
rongang rongang is offline
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Default Is this OK?

John - I performed your test as outlined above and the CPU passes MIDI signals from one keyboard to operate another one. The only thing is that the MIDI activity LEDs remain lit whether I am pressing a note on the controlling keyboard or not (a Roland RD-300NX digital piano to be specific). Is that OK? When I touch a wire from the ground to one of the control terminals of the MIDI CPU card, notes are operated should be, and the MIDI activity LEDS wink on the making and breaking of contact as should be.

My frustration is that I can't get a response from the MIDI CPU card from Sqwerl using an M-AUDIO UNO USB-MIDI adapter as I posted yesterday elsewhere in this forum. Now from the above, I've ascertained, I think, that the MIDI CPU card is operating properly and wired up properly. If you can point me in the right direction, I will be grateful.
Thanks

Ron
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Old 01-06-2014, 06:39 AM
rongang rongang is offline
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Default some progress

I found this post -http://forum.highlyliquid.com/showthread.php?t=1075
and was able to get a dump back from the MIDI CPU using Bome's SendSYSEX. Seems like jsloat has gone the same path a I'm attempting now. So now I know that the UNO is communicating... next step will be to try to program... YAY ... there's a light from the end of the tunnel.
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Old 03-16-2014, 09:44 AM
muzzlitebeer muzzlitebeer is offline
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Default

Oops! Sorry, I posted my question in the wrong thread. Please delete.

Last edited by muzzlitebeer; 03-16-2014 at 09:51 AM.
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