correct way to use Pico-PIO-USB with pico-sdk v2.2.0 (host + device + stdio)

[akohlsmith]

I am relatively new to the rpi pico (RP2040 specifically) and am trying to figure out the correct way to write an application which uses the dedicated USB peripheral as a USB device (CDC to start) and the PIO USB as a USB host which will talk to CDC devices like the FT232, CP2104, CH341, etc.. I have cloned the Pico-PIO-USB repo into the same parent directory that I have the pico-sdk as well as my own application, and my CMakeLists.txt contains

set(PICO_PIO_USB_DIR "${CMAKE_CURRENT_LIST_DIR}/../Pico-PIO-USB")
add_subdirectory(${PICO_PIO_USB_DIR} pico_pio_usb)

to make it aware of the Pico-PIO-USB library.

My target_link_libraries() looks like this: target_link_libraries(${PROJECT_NAME} PUBLIC pico_stdlib pico_pio_usb tinyusb_device tinyusb_host tinyusb_board)

running cmake .. from the build directory works, and the firmware builds with the tinyusb warning that stdio has been disabled because both host and device modes are enabled but I have worked around that by providing my own implementation (and it works with Pico-PIO-USB linked in (but not used) when I do not try to use host mode. (e.g. target_link_libraries() does not have tinyusb_host listed).

I make no code changes, just add tinyusb_host to target_link_libraries(), blow away the build directory, cmake .. and make again, the board fails to be seen by the host. (I have not enabled host yet, just brought in the library).

At this point I'm not sure what I'm doing wrong; Pico-PIO-USB is building and linking fine, but even without CFG_TUH_ENABLED and CFG_TUH_RPI_PIO_USB defined in tusb_config.h nor with any calls to set up the host port it fails to bring up the device side.

Can anyone help me figure out why the moment I link in tinyusb_host (without actually enabling host mode) the device-side breaks?

[akohlsmith]

I think I managed to answer my own question. The problem was with the USB device descriptors I was using; once I used the one from the host_hid_to_device_cdc example things started working with my stdio example and tinyusb_host enabled. I haven't yet dug into why though.

I've also noticed that trying to enable debugging by adding

#define CFG_TUSB_DEBUG 3
#define CFG_TUD_LOG_LEVEL 0
#define CFG_TUH_LOG_LEVEL 3

does not work as expected; the build complains about CFG_TUSB_DEBUG being redefined with the original definition in /pico-sdk/lib/tinyusb/src/tusb_option.h, although that definition is clearly protected:

// Debug enable to print out error message
#ifndef CFG_TUSB_DEBUG
  #define CFG_TUSB_DEBUG 0
#endif

But if I set these in my target_compile_definitions() in CMakeLists.txt then they seemed to work (although there are still some redefinition warnings because the command line is conflicting with the command line (?!) but at least it was working.

What is odd is that setting PIO_USB_DP_PIN_DEFAULT and CFG_TUH_RPI_PIO_USB within tusb_config.h works fine. I suspect there is some build debugging that has to be done to clean up the configuration of debugging.

Something else I have noticed is that connecting/disconnecting a device from the PIO USB pins is not detected -- detection of the connected device only occurs at powerup. If I enable hub support I can connect and disconnect devices from the hub all day long and it works, but connecting/disconnecting the hub from the PIO USB pins is also not detected. Is there a configuration option or some code I need to add to poll for host port connections/disconnections?

I'm now working on actually reading data from the CDC device; I have tuh_cdc_rx_cb() defined, but it doesn't appear to be called. I tried adding a call to tuh_cdc_connect() in my tuh_cdc_mount_cb() but that didn't cause the cdc_rx_cb to be called.