Encountered a problem sending more than 6 bytes of data using the hid service

[subllary]

Hello! I have found a question and answer on the forum about HID transmission that mentions HID can only send 6 bytes of data in boot mode, and suggests using UART for sending more bytes. However, I believe keyboards cannot use UART to send keystrokes. I would like to know if modifying the HID descriptor and changing boot to report can allow for sending more bytes of data.

static uint8_t                     report_map_data[] =
    {
        0x05, 0x01,         //   Usage Page 
        0x09, 0x06,         //   Usage (Keyboard),
        0xA1, 0x01,         //   Collection (Application),
        0x05, 0x07,       //   Usage Page (Key Codes),
        0x19, 0xE0,       //   Usage Minimum (224),
        0x29, 0xE7,       //   Usage Maximum (231),
        0x15, 0x00,       //   Logical Minimum (0),
        0x25, 0x01,       //   Logical Maximum (1),
        0x75, 0x01,         //   Report Size (1),
        0x95, 0x08,         //   Report Count (8),
        0x81, 0x02,       //   Input (Data, Variable, Absolute), ;Modifier byte
       
        0x95, 0x78,       //   Report Count (120)
        0x75, 0x01,       //   Report Size (1),
        0x15, 0x00,       //   Logical Minimum (0),
        0x25, 0x01,       //   Logical Maximum(1),
        0x05, 0x07,       //   Usage Page (Key Codes),
        0x19, 0x00,       //   Usage Minimum (0),
        0x29, 0x77,       //   Usage Maximum (120),
        0x81, 0x02,       //   Input (Data, Variable, Absolute),

        0xC0              // End Collection (Application)
    };

[SwRa]

Hello,

Do you have a link to the ticket that you have mentioned mentioned.? Also, are you using the nRF 5 SDK.?

-Swathy

[subllary]

Hello,

Thank you for your reply.I am using the nRF 5 SDK.,here's the link.

https://devzone.nordicsemi.com/f/nordic-q-a/77318/ble-hid-keyboard-sending-multiple-char-s-does-not-work

[Sigurd]

Hi,

Swathy is out of office, so I'm replying instead.

The USB-HID spec sets several limitations when it comes to sending words. You can max send 6 letters/keys in one HID transfer(Input Report), and it's not possible to send two of the same letters in one HID transfer.

[subllary]

HI,

I found the opposite conclusion on the Internet.

www.devever.net/.../usbnkro

[subllary]

HI,

I found the opposite conclusion on the Internet.

www.devever.net/.../usbnkro

[Sigurd]

Hi,

I have no experience with NKRO.

But it seems like e.g. Adafruit have a HID report map for this here that might be useful: https://learn.adafruit.com/custom-hid-devices-in-circuitpython/n-key-rollover-nkro-hid-device