Arduino as a dummy USB HID

Projects General Guidance
1

Hello,
I'm a software engineer wanting to get into IoT / embedded systems. I was thinking about a project lately, but I have only a vague idea on how it could be done, and I thought that maybe Arduino could be the right starting point to make a proof of concept.

What I want to do is a USB dongle that fakes its capabilities. That is, once inserted, I want it to present itself to the OS as a headset (microphone + speaker), or maybe, to start with something easier, as a keyboard. I want it to be able to be used with standard drivers at least on Linux.

The full project I have in mind is this: I want it to pretend to be a headset, so the OS sends it an audio stream and expects from it another audio stream. Also, I would simultaneously need another two data streams from/to the arduino (on the same USB, is it even possible?), call them DATA_IN and DATA_OUT. So four in total.

What I would like to do is something along this lines: some application on the machine is sending the Arduino an audio stream since it thinks it is a speaker; I take this audio on the arduino and loop it on DATA_OUT. At the same time, I inject data in DATA_IN and the Arduino loops it back on the microphone interface, and the application takes it.

Is this possible at all? I had a quick look at Arduino Nano Every, and I read that the firmware on the USB microcontroller SAMD11 can be customized, maybe that's the starting point to be able to make it present itself as a USB HID of some kind?

Thank you very much,
md

2

to be able to make it present itself as a USB HID of some kind?

Yes on some types of Arduino you can make a device look like a HID keyboard, mouse or even MIDI device. However, I know of no system that can handle audio in one direction let alone two.

3

Hi Mike, thank you for the quick reply.

However, I know of no system that can handle audio in one direction let alone two.

What do you mean? USB headsets having microphones + speaker are common. I imagine they work by presenting two HID to the OS, and then sending and receiving two data streams in parallel (or maybe on a time slot way).

4

USB headsets having microphones + speaker are common.

Yes I know, but they don’t use Arduinos. You are making the mistake in thinking because a thing is now common it can be handled by a 1980 power processor.

Most of these common devices use dedicated custom chips not general purpose controllers.

5

Teensy 3.x boards support audio over USB (bidirectional stereo), in combination with many other device types, such as HID (mouse/keyboard), Serial and MIDI.

Teensy 4.0 has hardware capabilities for more audio channels, but last time I checked, USB Audio wasn't implemented yet in the Teensyduino Core for this board.

That being said, just looping back the audio can easily be done using tools like pavucontrol or ALSA/Jack utilities on Linux.

If you want more portable audio applications, have a look at JUCE.

Pieter