Troubles with akai lpk25 and samsung marshmallow?

Questions and Discussions about G-Stomper
pie
Posts: 5
Joined: Thu Jun 01, 2017 1:46 am

Troubles with akai lpk25 and samsung marshmallow?

Postby pie » Wed Dec 27, 2017 8:51 pm

Hi, I just updated my samsung tab S t805 to android 6.01 MM stock, to make use of the new midi driver in gstomper.
I was on kitkat before, and my lpk25 was "working" out of the box with some (too much) latency.

I had to do a clean update, so I just reinstalled everything, plugged in my usbOTG cable, and gstomper recognized the akai lpk25: it didn't ask for the usb permission though.
The lights on the lpk25 just blink when the cable is plugged, then everything stays "off". I may be wrong, but I remember that some light was always "powered on" on kk.
The same happens with other apps using midi, so I assume it's something in the OS.
I've read that there was a Samsung bug on android 5, and that it should be gone in 6.x.. I am supposed to do something else, maybe in android settings?
If I plug in the controller to the tablet, I can't see the usual USB notification on the status bar, so I can't tell it to use it as a MIDI controller.

Any suggestion?
Thank you
User avatar
planet-h
Posts: 1039
Joined: Wed Jun 19, 2013 4:46 pm
Contact:

Re: Troubles with akai lpk25 and samsung marshmallow?

Postby planet-h » Thu Dec 28, 2017 11:11 am

Thanks for your message, Pie

pie wrote:Hi, I just updated my samsung tab S t805 to android 6.01 MM stock, to make use of the new midi driver in gstomper.
I was on kitkat before, and my lpk25 was "working" out of the box with some (too much) latency.

I had to do a clean update, so I just reinstalled everything, plugged in my usbOTG cable, and gstomper recognized the akai lpk25: it didn't ask for the usb permission though.
The lights on the lpk25 just blink when the cable is plugged, then everything stays "off". I may be wrong, but I remember that some light was always "powered on" on kk.
The same happens with other apps using midi, so I assume it's something in the OS.
I've read that there was a Samsung bug on android 5, and that it should be gone in 6.x.. I am supposed to do something else, maybe in android settings?
If I plug in the controller to the tablet, I can't see the usual USB notification on the status bar, so I can't tell it to use it as a MIDI controller.

Any suggestion?
Thank you

Generally, there's a major difference between Kitkat and Marshmallow.
Since Android 6, G-Stomper uses the Android M MIDI API.
This means, the USB permission is no longer required.
G-Stomper asks instead if you want to use the USB MIDI device in a regular (dark grey) popup window.
Do you see that popup when you plug in the LPK25?
Here's what you should see: http://www.planet-h.com/gstomper/docs/html/G-Stomper_UserManual_Midi/part10.htm
User avatar
planet-h
Posts: 1039
Joined: Wed Jun 19, 2013 4:46 pm
Contact:

Re: Troubles with akai lpk25 and samsung marshmallow?

Postby planet-h » Thu Dec 28, 2017 11:15 am

Regarding the samsung security bug, yes, this is definitely fixed in Android 6.
pie
Posts: 5
Joined: Thu Jun 01, 2017 1:46 am

Re: Troubles with akai lpk25 and samsung marshmallow?

Postby pie » Thu Dec 28, 2017 1:42 pm

Yes,I saw the gray pop-up and allowed it: I'd say it worked -at least to a certain extent- because the lpk 25 is correctly displayed in the set-up>MIDI menu but it's not "playing" anything.
As said, it seems that after plugging it in, it's no longer powered by the tablet(lpk25 doesn't have a power source except USB cable). It's not a USB cable issue because it was working on KK.
If it's a config issue, how may I check if it is sending something to gstomper?

Thank you
User avatar
planet-h
Posts: 1039
Joined: Wed Jun 19, 2013 4:46 pm
Contact:

Re: Troubles with akai lpk25 and samsung marshmallow?

Postby planet-h » Thu Dec 28, 2017 2:32 pm

pie wrote:Yes,I saw the gray pop-up and allowed it: I'd say it worked -at least to a certain extent- because the lpk 25 is correctly displayed in the set-up>MIDI menu but it's not "playing" anything.
As said, it seems that after plugging it in, it's no longer powered by the tablet(lpk25 doesn't have a power source except USB cable). It's not a USB cable issue because it was working on KK.
If it's a config issue, how may I check if it is sending something to gstomper?

Thank you

Once it's connected (means you've confirmed the popup and it's showing up in the MIDI setup), just exit the setup dialog and then play some keys on the LPK25. When you do so, you should see a MIDI DIN symbol flashing up at the left side of the play/stop/record button block. That symbol indicates that MIDI data is coming in, independent if it's mapped to some instrument or not.

If you do not see that flashing symbol, then it's most likely a power issue.
And since you say it worked with kitkat, it seems that Android 6 (which comes with a lot of new power saving functions) has reduced the provided power on the USB port.
I'm not sure if you can turn them off. If so, it would be in the system settings of your device under power saving, battery or similar. At least you should be able to turn all powersaving off for the G-Stomper app.
If there's no way to give the USB port more power, then the only way is a self powered USB hub (with an own power supply).

Hope that's helpful
Folkdisco
Posts: 21
Joined: Tue Dec 12, 2017 4:04 pm

Re: Troubles with akai lpk25 and samsung marshmallow?

Postby Folkdisco » Fri Dec 29, 2017 2:23 am

Pie: I haven't used much Android midi input in practice. But it is asking a lot of OTG to backwards power a midi device. Any power restrictions would *probably* be an attempt to protect circuitry on the phone, as much as battery life. If you do try a powered hub, please let us know how you get on either way. You do wish that phone and tablet manufacturers could have put separate power and OTG connectors on their devices. Alas, one socket is meant to do everything.
pie
Posts: 5
Joined: Thu Jun 01, 2017 1:46 am

Re: Troubles with akai lpk25 and samsung marshmallow?

Postby pie » Fri Dec 29, 2017 12:49 pm

Ok, I got it working: I am not sure what made the trick, but I:
- in developer settings set up USB to midi
- installed https://play.google.com/store/apps/deta ... iagnostics then run a diagnostic and it seemed to pass every test.

That's all I did, I don't need the external powered USB hub.

For the records, I found over the Internet that on some device models/firmwares it is possible to use a Y USB otg cable to charge the device while powering external USB equipment. But I didn't study this option, maybe it will come in handy to someone.

Thank you :)
Folkdisco
Posts: 21
Joined: Tue Dec 12, 2017 4:04 pm

Re: Troubles with akai lpk25 and samsung marshmallow?

Postby Folkdisco » Sat Dec 30, 2017 1:05 am

My understanding is that it is possible to charge a phone/tablet, but only at a very reduced rate while OTG is active. More like preventing battery drain. And you sometimes have to 'persuade' devices to do it, by plugging in the correct order, restarting, etc. I think it's probably easier to power your controller than charge your phone.
And cheers, great information, Pie! If you manage to charge, or anything else, please let us know. Like how's your latency now? Faster?
User avatar
planet-h
Posts: 1039
Joined: Wed Jun 19, 2013 4:46 pm
Contact:

Re: Troubles with akai lpk25 and samsung marshmallow?

Postby planet-h » Sat Dec 30, 2017 11:18 am

pie wrote:Ok, I got it working: I am not sure what made the trick, but I:
- in developer settings set up USB to midi
- installed https://play.google.com/store/apps/deta ... iagnostics then run a diagnostic and it seemed to pass every test.

That's all I did, I don't need the external powered USB hub.

Awesome, even if it's a somehow unexpected procedure to get it to work.
So after you did that, it just works in G-Stomper?
User avatar
planet-h
Posts: 1039
Joined: Wed Jun 19, 2013 4:46 pm
Contact:

Re: Troubles with akai lpk25 and samsung marshmallow?

Postby planet-h » Sat Dec 30, 2017 11:37 am

pie wrote:For the records, I found over the Internet that on some device models/firmwares it is possible to use a Y USB otg cable to charge the device while powering external USB equipment. But I didn't study this option, maybe it will come in handy to someone.

Yes, it is possible. But since it's not officially supported on 99% of the devices I'd recommend not to use it, as you do not have any guarantee that it won't damage your device.
What I'd recommend instead is to either use a device with wireless charging option, or to use Bluetooth MIDI controllers.

I did some deep tests with the new AKAI LPK25 Wireless and LPD8 Wireless, and I was surprised by the results (I was skeptical when I ordered the two devices). The latency difference is almost unnoticeable between hooking up the controller over USB (which is possible with both mentioned controllers) and connecting them over Bluetooth LE. Both controllers can be completely driven by their own batteries, means if the controllers are connected over Bluetooth, the USB port on the device is free to charge it while using the controllers.

Also a very nice Bluetooth LE controller is the LIVID Minim, it's sized like a smartphone, with an own rechargeable battery inside. It has touch sensitive pads and also gravity sensors.

Folkdisco wrote:My understanding is that it is possible to charge a phone/tablet, but only at a very reduced rate while OTG is active. More like preventing battery drain. And you sometimes have to 'persuade' devices to do it, by plugging in the correct order, restarting, etc. I think it's probably easier to power your controller than charge your phone.

Interesting point, didn't know about that. Thanks;)

Return to “General Questions and Discussions”

Who is online

Users browsing this forum: No registered users and 1 guest