tinyusb VS Adafruit_TinyUSB_Arduino

Implementing the required USB host interface is another hurdle, but tinyusb seems to have sorted most of that out, except that UAC2 is implemented as a device while you need a host.

Have a look at TinyUSB. It supports the STM32WB and demo programs for the Nucleo-WB55RG. It even offers an example for dual CDC ports, so very close to what you're looking for.

Second: Distrust, misunderstanding, and out of date opinions of C++ in embedded spaces. I often see "compatibilty" thrown around as a goal for using C and not C++, but for most modern embedded systems, C++ compilers exist and are (usually) well tuned. Arm is a shining example here*. C++ is more optimizable than C as the intent can be clearer to the compiler. C++ constexpr and templates are a godsend for embedded systems, and I used both heavily in my recent arduino and pico testing. I combined both of them for a really cool experimental USB interface descriptor builder that runs at compile time and avoids the need to count byte sizes, but I gave up on it when the maintainer said C only, despite the fact that C can't do that. I was similarly disappointed when the pico "C++" was C only, as there was no backwards compatibility necessary.

I looked at this but the fork seems to have had a lot of problems from looking at the PR: https://github.com/hathach/tinyusb/pull/1219

I think a better solution might be to use a USB flash drive in the usbc port. Unfortunately micropython and circuitpython don't support this (yet), so you'd have to use c++ https://github.com/hathach/tinyusb

It's possible to make the s3 be a mass storage device via TinyUSB. https://github.com/hathach/tinyusb/tree/master/examples/device/cdc_msc_freertos

https://gitlab.com/baiyibai/pico-w-usb-host-mqtt-numpad

https://github.com/adafruit/Adafruit_TinyUSB_Arduino

My implementation plugs in much higher into the stack and doesn't read the full USB bit mask output, which indicates how many keys are pressed/released.

From my limited understand ing, it should be possible to pass these USB messages from HID client to HID host and vice-versa. Then it's only a matter of sending this information over a TCP/UDP interface. However, from my research, it seems the TinyUSB library doesn't provide the full bitmask resolution necessary for all devices. The YouTuber Wendell from LevelOneTechs has also talked about the troubles of getting some devices working with his KVM products, so it may not be as simple as I'm suggesting here.

Overall though, a $15/endpoint is very attractive.

I'm curious about this restriction to ESP32-S series as shown here: https://docs.tinyusb.org/en/latest/reference/supported.html . This article https://www.pschatzmann.ch/home/2021/02/19/tinyusb-a-simple-tutorial/ claims that "Most Microcontrollers have a built in Serial USB functionality that can not be changed (e.g. ESP32, ESP8266". OTOH, https://github.com/adafruit/Adafruit_TinyUSB_Arduino indicates that all ESP32 chips are supported.

Well theorically any Arduino with a native USB connection (Atmega32u4, SAMD21, STM32, ESP32, Raspberry Pico...) would be able to do that, the difficult part is mostly finding a good library that can do that if you're not an ultra expert programmer. Here is an example, this one can support SAMD, ESP32 and Pico for instance (be careful you need specific cores to make it run). Here is an example how to use it

I have the Adafruit ESP32-S2 TFT board, and I am trying to read in a USB peripheral on my ESP board. I thought this was going to be an easy task and I am quite overwhelmed. I was hoping I could stay in the circuitpython ecosystem, but it seems like making the ESP32 a USBhost is not supported yet. My next level of comfort would be in the arduino ecosystem using https://github.com/adafruit/Adafruit_TinyUSB_Arduino. I believe this will do what I want, but I am having difficulty porting it into the Arduino core. Has anybody here done this successfully? I'm specifically stuck on #2:

Alternatively, go up a level and use Arduino and the Arduino TinyUSB wrapper library. This is also in active development with many recent MIDI fixes.

This is what you want https://github.com/adafruit/Adafruit_TinyUSB_Arduino There are examples for various USB device types.