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Thread: Teensy 3.6 Synthstation

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  1. #1
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    Teensy 3.6 Synthstation

    Hello all!

    I'm looking to do a project that's seems pretty similar to this one found on Hackster: C.H.I.P. MIDI Arpeggiating Synth but instead of using CHIP, I'm of coarse looking to use a Teensy 3.6...

    Basically, I want to hack into my Akai Synthstation 25 in order to use the Teensy audio libraries to initiate sounds to feed through the Synthstation. Also still being able to use the MIDI capabilities of the SS would be ideal as well.

    So far I've bought & soldered on the pins to use the optional USB host cable and have tried hooking the SS to the Teensy via that solution but when I fire up the example found: File > Examples > USBHost_t36 > Test the Teensy seems to be getting mixed messages during the upload process and borks out. It's only when I detach the SS from the Teensy's USB host cable that it will properly program. Yet upon reattaching the now programmed Teensy to the SS there doesn't seem to be any activity happening. FYI, I have he Teensy setup to use serial/midi/audio atm.

    My first question I guess is what I'm hoping to achieve even possible? Then secondarily if so am I going about it the right way with this USB host cable or should I be looking to connect to the Akai Synthstation's PCB boards directly? I've taken the SS completely apart and examined all the pieces so I have access to some pins if I can figure out which ones do what exactly. I've taken pictures of each PCB board in the SS so if anyone thinks seeing those would help assess the situation I'd be more than happy to post them here.

    Thanks in advance for any advice or help!

  2. #2
    Senior Member PaulStoffregen's Avatar
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    Quote Originally Posted by ideletemyself View Post
    My first question I guess is what I'm hoping to achieve even possible?
    Yes, this should be possible.

    So far I've bought & soldered on the pins to use the optional USB host cable and have tried hooking the SS to the Teensy via that solution but when I fire up the example found: File > Examples > USBHost_t36 > Test the Teensy seems to be getting mixed messages during the upload process and borks out. It's only when I detach the SS from the Teensy's USB host cable that it will properly program.
    Something's probably connected incorrectly.

    I can confirm uploading works here when my Teensy 3.6 is connected to a MIDI keyboard by the USB host cable.

    Then secondarily if so am I going about it the right way with this USB host cable
    Well, I don't have an Akai Synthstation 25, so without seeing details photos and info, the best advice I can give is based on the MIDI keyboards and other devices I do have. This is the one I usually use for testing:

    https://www.amazon.com/midiplus-AKM3.../dp/B00VHKMK64

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    Quote Originally Posted by PaulStoffregen View Post
    Yes, this should be possible.



    Something's probably connected incorrectly.

    I can confirm uploading works here when my Teensy 3.6 is connected to a MIDI keyboard by the USB host cable.



    Well, I don't have an Akai Synthstation 25, so without seeing details photos and info, the best advice I can give is based on the MIDI keyboards and other devices I do have. This is the one I usually use for testing:

    https://www.amazon.com/midiplus-AKM3.../dp/B00VHKMK64
    Thanks for the quick reply Paul!

    I'm not sure what's going wrong as I've re-soldered the pins for the USB host cable 3 times now with no better results each time. Pretty sure I did the best I could each time cleaning it all up and then applying flux, etc. Here are some pics:

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    To be sure my Akai Synthstation wasn't the issue I went ahead and connected my Korg Monologue synth/midi keyboard which I know works just fine and I got the same results. Could the USB host cable be the issue? Or is this all due to a poor initial soldering job? I do have access to a hot air rework station so I suppose I could de-solder the pins AGAIN and then use the hot air to absolutely melt any remaining solder away??

    Again, the Teensy works just fine otherwise. I can use it's MIDI usb capabilities to use a couple potentiometers to change MIDI in my DAW. So I'm definitely at a loss of ideas. Any input would be greatly appreciated..

    Oh and here's what Windows Device Manager shows:

    Click image for larger version. 

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    Thanks again!

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    Well, I'm pretty sure I've fried my Teensy lol...

    Thanks for the help, now that I know I'm going about it the correct way I just need to do a better job on the initial soldering of the pins I think.

    I've gone ahead and ordered another 3.6 through Amazon so hopefully I'll have that by midweek. I'll update this thread once I have the new Teensy and hopefully better results!

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    Just an update, maybe someone can give some feedback as to what might be happening...

    So I tried using the 3.6 I thought I'd fried, on another computer which is an Ubuntu laptop. And after getting things working with an Arduino Micro I was able to get the Teensy 3.6 to fire up the LED blink example on that laptop. I switched back to Windows and now I can get the LED blink example to work on there as well. Whereas previous it wasn't even being seen in device manager properly.

    It appears that the Teensy still might be good. I suppose I'll give the USB host cable another go. Really do hope this 3.6 is okay and I needed another 3.6 anyways for another project so this might work out for the best.

    I guess what I'm getting at is that am I going to expect intermittent functionality from here on out at best on this 3.6? Any input would be welcomed, thanks!
    Last edited by ideletemyself; 12-26-2017 at 03:02 AM.

  6. #6
    Senior Member PaulStoffregen's Avatar
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    Quote Originally Posted by ideletemyself View Post
    Just an update, maybe someone can give some feedback as to what might be happening...
    First, try adding a 10 second delay before usb.begin() to turn on the USB host hardware. Or add a "while (!Serial) ; " line. The idea is to wait for your PC to full detect Teensy. Maybe even print some stuff to the serial monitor, and delay for several milliseconds so it gets an opportunity to actually transmit over the USB cable to your PC, and then turn on the USB host.

    Perhaps this is simply a power problem? Most PCs can provide 500 mA. But that power needs to run both Teensy 3.6 and whatever device you're plugging into 3.6's host port. However, if you're plugged into an unpowered USB hub, you might not have enough power available. Maybe you've got just barely enough power for Teensy 3.6, and then when you turn on the USB host port and the Synthstation also starts using power, perhaps it's just too much and everything stops working. If Windows hasn't completed reading the USB info from Teensy, you'd see that sort of "Code 10" or "Code 43" error in Windows (Microsoft doesn't seem to like actually giving any real info, do they...)

    The other alternative, which I would not recommend you try until you've at least checked with other ports and maybe measured with a voltmeter, is an external 5V supply with the VUSB-VIN pads cut apart on the bottom side of the Teensy. Then your 5V supply will power everything, and you can use one that's rated for 1A or more to make sure you have enough power.

  7. #7
    Senior Member+ defragster's Avatar
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    Quote Originally Posted by ideletemyself View Post
    ... am I going to expect intermittent functionality from here on out at best on this 3.6? ...
    Unless you harm the Teensy - No.

    What version of Windows?

    I had some Teensy's go offline a bit on Windows 7 - if I programmed a second on the same machine the first would then work. Not seen that using Windows 10 IIRC. The other day I was tormenting USB on waking from Snooze sleep and Win 10 got mad at that USB port - device moved to another worked and then after a bit going back - when that one got mad too - the prior one was reset to working and had not rebooted.

    But other than one T_3.6 I got swapped - I've not had issues with other T_3.6's including the KS Beta T_3.6 and the PROTO that came before it that still work like the others I've soldered up and still using. Worst case was the 15 second button press processor reset - but none of that recently.

  8. #8
    Senior Member PaulStoffregen's Avatar
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    Did you try the 10 second delay and measuring voltage (message #7)? Very possible these problems are simply power related, which would explain why a 2nd Teensy does exactly the same thing as the first.

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    Quote Originally Posted by PaulStoffregen View Post
    Did you try the 10 second delay and measuring voltage (message #7)? Very possible these problems are simply power related, which would explain why a 2nd Teensy does exactly the same thing as the first.
    I did try adding the delay but didn't seem to get any better results at the time on either of the 2 different PC's(Windows & Ubuntu laptops) I've been trying at home. Both the Synthstation & the Korg Monologue were using their own power via power adapters and they even had full batteries in their respective compartments. Would power still be an issue in that case??

    I do have a cheap multimeter how would I go about measuring, just basically check to see if the power pin on the 3.6 for the USB host cable reads 5V? Thanks again for your assistance!

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    Hmm, well shoot you may be correct of coarse lol!

    Not sure if my re-solder job(I couldn't help myself) did it or maybe the Mouse example was working last night as well and I wasn't checking the serial monitor like a dumbass... But at any rate I CAN confirm functionality with the USB host cable and the example found at File > Examples > USBHost_t36 > Mouse as shown by this screen shot:

    Click image for larger version. 

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    Unfortunately I don't have any USB MIDI keyboards with me atm so I'll have to wait until I get home to continue testing but I'm at least confident that all this hardware DOES work. So...

    If power IS the issue and it's really seeming like it is despite the keyboards having their own power. Can you give any examples or links to a power supply that would suffice as you described here in message #7?

    The other alternative, which I would not recommend you try until you've at least checked with other ports and maybe measured with a voltmeter, is an external 5V supply with the VUSB-VIN pads cut apart on the bottom side of the Teensy. Then your 5V supply will power everything, and you can use one that's rated for 1A or more to make sure you have enough power.
    Thanks again for everything so far. I'm very happy to be making some progress!
    Last edited by ideletemyself; 12-29-2017 at 04:44 PM.

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