AnsweredAssumed Answered

Freescale USB stack v4.1.1

Question asked by Mohamed Ismail Bari on Jan 28, 2015
Latest reply on Jan 29, 2015 by Mohamed Ismail Bari

Hi,

 

I am using Freescale USB stack v4.1.1 on K22 processor. I am defining my device descriptors on RAM memory as shown below.

 

uint_8 g_device_descriptor[DEVICE_DESCRIPTOR_SIZE]=

{

DEVICE_DESCRIPTOR_SIZE,                /*  Device Descriptor Size         */

USB_DEVICE_DESCRIPTOR,                 /*  Device Type of descriptor      */

...

}

 

If I change the device descriptor (or any other descriptor) to FLASH area (as shown below) then I don't get proper USB enumeration.. Does Freescale USB stack work only with descriptors defined in RAM memory? I checked the K22 datasheet/reference, there is no restriction on the address in the BDT entry.

 

uint_8 const g_device_descriptor[DEVICE_DESCRIPTOR_SIZE]=

{

DEVICE_DESCRIPTOR_SIZE,                /*  Device Descriptor Size         */

USB_DEVICE_DESCRIPTOR,                 /*  Device Type of descriptor      */

...

}

 

Could any one shed some light on this please?

 

Thanks,

-Ismail

Outcomes