USB custom HID increase report Size from 64 to 256 bytes?

ADIt · ‎2018-12-27

hi I want to transfer 256 bytes from host to stm32 device over Custom HID interface

Following is the report desc in my stm32,

/** Usb HID report descriptor. */

__ALIGN_BEGIN static uint8_t CUSTOM_HID_ReportDesc_FS[USBD_CUSTOM_HID_REPORT_DESC_SIZE] __ALIGN_END =

{

0x06,0x00,0xFF, //Usage Page 0xff00

0x09, 0x01, //USAGE (Pointer)

0xA1,0x01, //Collection (application)

//Input Report

0x19,0x01, //Usage Minimum

0x29,0x40, //Usage Minimum

0x15,0x00, //Logical Minimum

0x26,0xFF,0x00, //Logical Minimum

0x75,0x08, //report size : 8-bit field size

0x95, CUSTOM_HID_EPIN_SIZE, //Report count

0x81,0x02, //Input (data, array, Abs)

//Output Report

0x19,0x01, //usage Minimum

0x29,0x40, //usage Minimum

0x75,0x08, //report size : 8-bit field size

0x95,CUSTOM_HID_EPOUT_SIZE, //Report Count

0x91,0x02, //Output (data, array, Abs)

0xC0 //END_COLLECTION

};

If i am changing the CUSTOM_HID_EPIN_SIZE,CUSTOM_HID_EPOUT_SIZE to 256 my USB device is unable to be recognized.

So, i need some help to modify the report desc to support 256 byte transfer

Thanks

S.Ma · ‎2018-12-27

Unless I'm wrong, the USB message duration is limited in time. USB FS (Full Speed) devices and messages, regardless of the class are limited to 64 bytes packets and 1 msec polling. The raw bitrate is 12mbps if I remember well. You would need to use HS (high speed) interface to get up to 512 bytes and faster message rate.

ADIt · ‎2018-12-28

Hi,

Thanks for the answer ,

The MCU in my case is STM32F103c8t6.

I think it doesn't have USB High speed USB interface only has Full-speed