PORTS Forum

Ports and Interfaces => USB => Topic started by: ulao on July 01, 2017, 11:17:56 pm

Title: can Report requests have arbitrary payload sizes?
Post by: ulao on July 01, 2017, 11:17:56 pm

for example I have this


    0x85, 0x12,                    //   REPORT_ID (18)
    0x95, 0x83,                    //   REPORT_COUNT (131) -- the max
    0x09, 0x00,                    //   USAGE (Undefined)
    0xb2, 0x02, 0x01,              //   FEATURE (Data,Var,Abs,Buf)
    0xc0,                           // END_COLLECTION

but I must use 132 bytes, can allow this report to accept other size data or do I have to fill with zeros.

Title: Re: can Report requests have arbitrary payload sizes?
Post by: Jan Axelson on July 02, 2017, 11:21:04 am

HID reports must be of a size defined in the report descriptor. The Windows HID driver will ignore any received reports of other sizes.

Title: Re: can Report requests have arbitrary payload sizes?
Post by: ulao on July 02, 2017, 02:23:51 pm

That is what my issue was, so was wondering if that was an option. I guess the firmware can always return 1 and tell the driver it got what it needs short of the entire pay load.