K81/82 USB accessing Flash area

[izmile]

Hi,

I am using K81 / K82 MCUs and got the USB CCID interface working. If I move the USB descriptors to flash area, then USB enumeration fails. I have tried the following but it doesn't work.

/* Disable MPU. All accesses from all bus masters are allowed now. */
MPU_CESR = (0);

// Set read access for USB master #3

FMC_PFAPR |= FMC_PFAPR_M3AP(01);   // USB is master #3

// USB master 3 is trusted for read access

AIPS0_MPRA |= AIPS_MPRA_MTR3(1);

Is there anything I am missing?

Thanks,

-Ismail

[jorge_a_vazquez]

Hi Mohamed

You just need to set your access, I don't see anything that is missing.  I set String descriptors in flash and I enable the flash read access to USB, and it works in my side but maybe the error is in the descriptors, how you set them in flash? could you verify that they are property set in this are?

void APP_init(void)
{
    cdc_config_struct_t cdc_config;
    FMC->PFAPR |= FMC_PFAPR_M3AP(0x03);
    cdc_config.cdc_application_callback.callback = USB_App_Device_Callback;
    cdc_config.cdc_application_callback.arg = &g_app_handle;‍‍‍‍‍‍‍‍‍‍‍‍

Best Regards
Jorge Alcala

[mjbcswitzerland]

Hi

I confirm that I didn't see any problem with the settings; they are the same as used in the uTasker K80 USB stack, which always has the descriptors in Flash.

There is a USB-MSD loader for the K82 at http://www.utasker.com/kinetis/FRDM-K82F.html and with a debugger it should be possible to compare settings in the peripherals to be sure (as well as verifying that the operation with descriptors in Flash are OK).

Regards

Mark

[izmile]

Thanks for your replies. I am sure this would be a silly mistake in the code. I will update my findings shortly.

PS: Tossed around on another project.

[mjbcswitzerland]

Hi

Verify that FMC_PFAPR_M3AP(01);   // USB is master #3

gives 0x00000040

The macro is not transparent and so the value may be incorrect (?)

Regards

Mark

[izmile]

Yes, the macro FMC_PFAPR_M3AP(01) set the bits properly. I do some more digging around.