HID output report size and count

[ilia]

Hello,

I am developing a simple HID device with output report to receive data from PC. I took keyboard example as base project and I want to increase output report size (count) up to 64 bytes. 

I can successfully send data from PC to device when output report is not larger than 1 byte. If I change size or count in descriptor, data transmission is not working.

I use c# code to connect to device and send byte buffer. It does not show any errors, I have just "success" or "fail".

Device is recognized by the PC correctly.

Here is my descriptor

#define HID_CONTROL_REPORT_DESCRIPTOR() {                \
    0x05, 0x01,                    /* USAGE_PAGE (Generic Desktop)*/	\
    0x09, 0x00,                    /* USAGE (Undefined)*/	\
    0xa1, 0x01,                    /* COLLECTION (Application)*/	\
    0x75, 0x08,                    /*   REPORT_SIZE (1)*/	\
    0x95, 0x01,                    /*   REPORT_COUNT (1)*/	\
    0x15, 0x00,                    /*   LOGICAL_MINIMUM (0)*/	\
    0x25, 0x7F,                    /*   LOGICAL_MAXIMUM (127)*/	\
    0x09, 0x01,                    /*   USAGE (Consumer Control)*/	\
    0x91, 0x02,                    /*   OUTPUT (Data,Ary,Abs)*/	\
    0xc0                           /* END_COLLECTION*/	\
}

It works perfectly. But if I increase REPORT_COUNT, or REPORT_SIZE, it stops receiving data from PC

[Dmitry]

Have you tried report length lower than 64 bytes? Length of the report cannot be longer than length of a BLE packet (20 bytes by default, and we had no success to send larger reports even with increased packet length). Also note that HID report packet that comes from PC should have a length exactly as report count in your descriptor, first byte is a report ID that is 0x00 by default, so your report  will start from byte 0x00 and take (REPORT_COUNT-1) bytes of your data. Though I am not sure whether it is correct in case with c#, I use hidapi library that handles all this magic for me.

Here is my working in-out HID descriptor:

	0x06, 0x00, 0xff,  // USAGE_PAGE (Vendor Defined)
	0x09, 0x01,        // USAGE (1)
	0xa1, 0x01,        // COLLECTION (Application)
	0x09, 0x20,        // USAGE (Input Report Data)
	0x15, 0x00,        // LOGICAL_MINIMUM (0)
	0x26, 0xff, 0x00,  // LOGICAL_MAXIMUM (255)
	0x75, 0x08,        // REPORT_SIZE (8)
	0x95, 0x14,        // REPORT_COUNT (20)
	0x81, 0x02,        // INPUT (Data,Var,Abs)
	0x09, 0x21,        // USAGE (Output Report Data)
	0x15, 0x00,        // LOGICAL_MINIMUM (0)
	0x26, 0xff, 0x00,  // LOGICAL_MAXIMUM (255)
	0x75, 0x08,        // REPORT_SIZE (8)
	0x95, 0x14,        // REPORT_COUNT (20)
	0x91, 0x02,        // OUTPUT (Data,Var,Abs)
	0xc0               // END_COLLECTION

[ilia]

Hi. Yes, I tried different report length. I use HID over USB, not over BLE. I tried to use your descriptor, but I got the same failed result. When I changed report count to 1, data was sent successfully. I tried to use hidapi from c, and I got the same results. 

Maybe I need to make some additional configuration in firmware on the device?