Cannot configure USB Serial Communication over USB-A on Portenta Machine Control

[MKOSdm]

I am trying to configure USB serial communication (CDC ACM) over the USB-A port on my Portenta Machine Control. Despite initializing the USB host and adding the CDC backend to the class table, my program cannot detect or communicate with the connected USB device.

[leonardocavagnis]

Hey! Could you provide more details about your setup and the sketch you're using? Thanks

[EnterraBunny]

I have the same issue on the H7 Portenta Machine Control. While trying to figure it out I'm finding issues in the USBHost library.

I have the keyboard and mouse examples working, but CDC has problems. I need to communicate with a radio module that has a built-in FTDI interface which shows up at VID 0x403, PID 0x6015. The library doesn't recognize that - doesn't like the PID as a CDC device.

I got past that with this modified declaration in tusbh_cdc_acm.c:

const tusbh_interface_backend_t  tusbh_cdc_acm_backend = {
    .vid = 0x403,
    .pid = 0x6015,
    .bInterfaceClass = 0,    // changed, was USB_CLASS_CDC,
    .bInterfaceSubClass = 0,
    .bInterfaceProtocol = 0,
    .init = tusbh_cdc_acm_init,
    .deinit = tusbh_cdc_acm_deinit,
    .data_xfered = tusbh_cdc_acm_xfered,
    .desc = "MY CDC ACM",
};

Also line 844 in tusbh.c is wrong - here's my version which prints status rather than claiming perpetual failure.

           while (res!=0){
                res = tusbh_device_attach(dev);
                TUSB_ROOT_INFO("Device attach status= %d\n", res);   /// <<< changed
            }

But I still don't have any data arriving.

[EnterraBunny]

I also had good luck setting .bInterfaceClass = USB_CLASS_VEND_SPECIFIC (( 0xff ) which at least enumerates 3 different FTDI devices. Still no data traffic.