Teensy sitting between USB host and client(s): feasibility & power supply

[b6d]

Hi,

I hope this isn't out of scope for this forum:

I have a synthesizer (Synthstrom Deluge) that has a USB host port for a USB MIDI controller (or controllers when using a USB HUB).

I would like to have a Teensy 4.1 in between the Synth and the controller(s) to mediate MIDI messages for various reasons, like so:

                                       +-- USB MIDI controller
                                       |
Synthesizer <-- Teensy <-- USB HUB <---+-- USB MIDI controller
                                       |
                                       +-- USB MIDI controller

I'm wondering if this is possible at all with building on available USB and MIDI libraries for Teensy.

And since this is for a space and power constrained project, I'm also wondering (if possible) what the most sensible setup would be in terms of size and power.

I assume the synthesizer's USB host supplies 500 mA at most; and current requirements would be the Teensy's current draw plus the current draw of all the controllers. I'm fearing this might exceed the 500 mA in the worst case.

(to supply power, I have a few isolated 9 V / 500 mA power outputs as used for guitar pedals. For other USB powered devices in that setup (unrelated for this purpose) I use buck converters to step down to 5V.

If this is even possible at all, I'm currently clueless on how to power all this without frying something. If supplying additional power to the whole setup is too complicated, I'd be willing to compromise.

I would be very grateful for some insight and maybe some pointers into the right direction. (Even if that insight would be that this project would be unfeasible).

PS: This is the firmware i would like to base this on.

 

[kd5rxt-mark]

After just a quick look (I did not go to look at the firmware that you referenced), I'd answer your questions as follows:
- yes, you can certainly place the Teensy 4.1 between the Synth & the USB hub. The primary USB interface on the Teensy 4.1 would be plugged into the Synth's USBhost port, and the USB hub would plug into the Teensy 4.1's USBhost port. The MIDI library provides capabilities that should make it very easy to achieve your desired message mediation.
- as for USB power, I would suggest using a powered USB hub . . . that lets the USB hub to manage the power draw, of the downstream MIDI devices, rather than the Teensy 4.1 or the Synth

Hope that helps . . .

Mark J Culross
KD5RXT

 

[b6d]

Hope that helps . . .

Thank you! It does - a lot!

Knowing the libraries should be capable of handling this easily is a big relief. And for some reason I always ruled out active USB hubs for the extra power brick. Your comment inspired me to look again and i found one that i can power with my guitar pedal power supply. Seems like the best trade off between simplicity and saving space!