Hi All,
Here's some context first. I'm trying to connect my guitar amp to a teensy 4.1 via usb in order to control the amp via some custom code running on the teensy. The end goal is to be able to turn effects on and off via some foot switches. The messages I need to send to the amp are sysex midi over usb, and I already found plenty of resources on that topic. But most (all) people doing such thing seems to be using an SPI to USB adapter instead of a built-in usb like I want to do with my teensy 4.1.

I think I need to select "Serial + MIDI" in the Tool, USB type menu in the Arduino IDE. Am I correct in assuming that this means the programming USB will stay as my Serial link for debug and the other USB (the one I soldered to the usb host cable) will be my host for the amp and I will be able to talk to it via MIDI commands ?

I think my best bet will be to use usbMIDI.sendSysEx() right ?

Is there something I need to run to initialise the usb, or the midi ? Before I send any command, how can I check that something is connected to the usb host ? And how can I query it to know what it is ?