Midi out powered ?

[djbclark]

I tested with USB power from computer, USB power from a battery, and with a 9v battery. First unit briefly worked with the 9v, second unit briefly worked with USB power from computer.

My top level concern is that the WIDI Master units seem to break completely after being connected to the eDrummin 4 briefly, eg afterwards does not work on hardware previously tested to work fine with it.

Even if the workaround works perfectly, I wouldn't trust myself to remember to use it all the time to avoid loss of the $50 WIDI Master (or $40 rebranded version) unit.

I do not know what side is to blame here. It seems quite possible to me that CME deviates from the official spec; perhaps in general industry practice deviates from the actual spec. And of course there is always the possibility I'm consistently doing something wrong across all three units I've tested.

Its not complete destruction; no burning smells, Bluetooth connections still work, LED blinks when notes are hit. It's just that no notes or any other MIDI messages are actually sent.

[djbclark]

BTW is there a simple way to use an oscilloscope or multimeter to verify the specific MIDI Out power on my unit is operating as expected?

[Rob]

Certainly.

image.png (299.06 KiB) Viewed 1362 times

Pin 2 is ground
Pin 4 is 3.3V
Pin 5 is the MIDI signal

Using a multimeter between pin 2 and 4 should register 3.3V. Using an scope between pin 2 and pin 5 will should your MIDI messages. I highly doubt the MIDI Master could be damaged. There's no way it could pass EMC testing if 3.3V could damage it in any way.

https://learn.sparkfun.com/tutorials/mi ... ementation

[djbclark]

So my unit is fine, 3.28v (on a cheap multimeter).

I agree that this should not be happening / everyone is almost surely up to spec.

However my experience is that I've destroyed 3 units' abilities to send MIDI data.

[Rob]

I did extensive testing on my MIDI out port because I take someone saying that my hardware is causing other hardware to fail very seriously. The loop current coming out of all my devices is about 5.9 mA (assuming that the receiver has a properly designed MIDI in with an opto-isolator). The MIDI spec calls for 5 mA, but that is a minimum and the vast majority of MIDI manufacturers output between 5 and 10 mA.

I my opinion, I think you need to look elsewhere for the source of your problems. That said, I have purchased a CME WIDI Master and I'll test when it arrives and I'll report back my findings when it arrives.

[djbclark]

My guess at this point is a software bug in the WIDI Master.
(One thing I didn't try that looking back I should have is re-flashing the firmware after it stopped working - this is done via their Android or iPhone app.)

Thank so, so much for getting one to test!

I sure hope you see the same issue I did

[djbclark]

That said, I have purchased a CME WIDI Master and I'll test when it arrives and I'll report back my findings when it arrives.

Any news? It's time to start making X-Mas lists :-)

Happy Hollidays,
-Danny

[Rob]

The adapter never made it here. I'll need to find another supplier.

[djbclark]

It looks like maybe they have been taken off the market either due to issues or chip shortage - Amazon only has them from 3rd party suppliers, Thomann doesn't have them at all, etc. Even the Xvive semi-clone is off the market.

The WIDI Jack, not quite as cute but also MIDI OUT powered, seems to still be around:
https://www.amazon.com/CME-WIDI-Jack-DI ... B09K46681M

Also it surprised me that Amazon actually sells the chips, albeit at an extortionate price:
https://www.amazon.com/CME-WIDI-Core-im ... B0BBW5JF8V

[djbclark]

I decided to get a WIDI Jack as it was on sale. It's arriving Sunday; I'll report back with what happens next week. If there is anything specific you'd like me to do with it let me know.