RP2040 MIDI host

[atoktoto]

Describe the PR
This PR adds MIDI host support for RP2040 boards based on work done by @rppicomidi in #1219 and @Skyler84 in #1434. I rebased all changed on top of master and fixed some compilation errors.

MIDI controller (behringer x-touch mini) enumerates and the data is received.

Creating this pull request as a draft for comments. I'm very new at this and I'm kind of surprised that it works :D

[todbot]

Hi!
I'm very excited for this functionality. But I'm getting compile errors when I try this out. The process I'm using:

git clone https://github.com/atoktoto/tinyusb tinyusb-atoktoto
cd tinyusb-atoktoto
git checkout midihost-atoktoto
git submodule update --init lib
cd examples/host/midi
make BOARD=raspberry_pi_pico get-deps
make BOARD=raspberry_pi_pico all

And I get the error:

[...]/tinyusb-atoktoto/examples/host/midi/src/midi_app.c:195:16: error: unused variable 'bytes_read' [-Werror=unused-variable]
  195 |       uint32_t bytes_read = tuh_midi_stream_read(dev_addr, &cable_num, buffer, sizeof(buffer));
compilation terminated due to -Wfatal-errors.
cc1: all warnings being treated as errors

Okay, perhaps you're assuming you must have LOG set, so I clean and build with:

make BOARD=raspberry_pi_pico LOG=2 all

and now the error I get is:

<command-line>: error: "CFG_TUSB_DEBUG" redefined [-Werror]

Well, I can go back to doing a normal build and just insert a (void)bytes_read; on line 196, after the offending line, to get the compiler warning to go away. But then when I compile I get this error:

[...]/tinyusb-atoktoto/src/host/usbh.c: In function 'tuh_task_ext.part.0':
[...]/tinyusb-atoktoto/src/host/usbh.c:478:41: error: array subscript 1 is above array bounds of 'uint8_t[1][2]' {aka 'unsigned char[1][2]'} [-Werror=array-bounds]
  478 |             uint8_t drv_id = dev->ep2drv[epnum][ep_dir];
      |                              ~~~~~~~~~~~^~~~~~~

Am I doing something wrong? Can you please share the build steps you're using?

[atoktoto]

Not sure if that's the source of the problem but the way I have it set up is the same as described by the original author of this merge request: https://github.com/rppicomidi/midi2usbhost ( "Using the forked tinyusb library" )

The top level directory for me is pico-examples. The CMakeLists.txt there adds the examples from tinyusb.

I will test starting from empty directory later today.

[atoktoto]

Here is a stripped down project created from the example: https://github.com/atoktoto/pico-midi-host

[rppicomidi]

@atoktoto In case you are interested, my fork of this project has a new branch pio-midihost that supports the Pico-PIO-USB as a host. I have a demo project pico-usb-midi-filter that passes MIDI data between the built-in USB configured as a device and a new USB Host port created from PIO. I suspect I duplicated some of your work in this pull request in my fork.

[atoktoto]

@rppicomidi Is the Pico-PIO-USB a way to go over the dedicated hardware? Why?

I've used the branch you mentioned, applied #1434 and it seems to work without PIO. I think I will re-create this merge request with your changes and #1434.

[rppicomidi]

@atoktoto I agree #1434 seems to work. I am not arguing against your pull request. Thank you for doing the work. The pico-usb-midi-filter project uses a single Pico board to implement a bi-directional MIDI filter between a MIDI USB host (which I implemented using PIO from the Pico-PIO-USB project) and a MIDI USB device (which I implemented using the Pico's dedicated USB hardware). My comment was only wishing I had looked here before I did a lot of the same work you did.