support issue - how to use

[stanelie]

Hello.
It's unclear to me how I should use this library. A thing I would like to do is use some randoms pins on a RP2040-zero as a USB host port to connect a midi keyboard that uses midi over USB, and then use sythio to generate some sounds.

Is this scenario something that I should be able to do with this? How do you specify which pins to use for the USB host connexion?

Thanks for any help!

[dglaude]

I am not sure about the "random pins" because they need to be consecutive for the PIO that does USB-Host on RP2040 to work.
Worst I don't know how to specify the pin to be used.

I would start with a supported board such as the Feather RP2040 with USB Host, or check what pin are used on that board https://learn.adafruit.com/adafruit-feather-rp2040-with-usb-type-a-host/pinouts

I am not sure how to replicate that on a RP2040-zero as the firmware does not define USB port such as in the Feather RP2040 USB Host:

{ MP_ROM_QSTR(MP_QSTR_USB_HOST_DATA_PLUS), MP_ROM_PTR(&pin_GPIO16) },
{ MP_ROM_QSTR(MP_QSTR_USB_HOST_DATA_MINUS), MP_ROM_PTR(&pin_GPIO17) },
{ MP_ROM_QSTR(MP_QSTR_USB_HOST_5V_POWER), MP_ROM_PTR(&pin_GPIO18) },

Or the Waveshare RP2040 PiZero:

{ MP_ROM_QSTR(MP_QSTR_USB_HOST_DATA_PLUS), MP_ROM_PTR(&pin_GPIO6) },
{ MP_ROM_QSTR(MP_QSTR_USB_HOST_DATA_MINUS), MP_ROM_PTR(&pin_GPIO7) },

I hope there is a dynamic way to define what pin to use, but I don't have the answer to that.

[stanelie]

From the Adafruit Feather schematic here https://cdn-learn.adafruit.com/assets/assets/000/120/409/original/hacks_schem.png?1682345733 , I see the usb host pins only require an inline 22 ohm resistor to the connector. Is that it? I only need to add those resistors to my RP2040-zero and off I go, it should work?

Should this be in the documentation of this library? Or should it be stated that this library only works with the Feather?

[tannewt]

Try it without the inline resistors. I've used it without.

Here is an example that sets up the USB host pins from CircuitPython: https://github.com/adafruit/circuitpython/blob/main/tests/circuitpython-manual/usb/device_info.py

Specifically:

h = usb_host.Port(board.USB_HOST_DP, board.USB_HOST_DM)

[stanelie]

Great, thanks!