BLE HOGP HID report string

[Sam@Manus]

According to the HID Usages and Descriptions document (0333.hut1_4.pdf) (p29), strings on a HID device are accessed using a Language ID and a string index. Using that information from the report, the string can be retrieved from a USB String Descriptor. I couldn't find any documentation neither from Nordic, nor from the Bluetooth SIG about how this would work over BLE with the HID over GATT profile. Could anyone please explain how to report strings like this with HID over GATT or link me a resource that does?

[Sigurd]

Hi,

I believe these types of stings, e.g. manufacturer name, serial number, etc., are using the Device Information Service.

https://www.bluetooth.com/specifications/specs/device-information-service-1-1/

Device Information Service is a mandatory service for a HID over GATT device.

https://www.bluetooth.com/specifications/specs/hid-over-gatt-profile-1-0/

[Sam@Manus]

Hi,

Thank you for your reply. I realize that's how it works for device information, but there are other usages like "Keyboard IETF Language Tag Index", "iDevice Chemistry" and possibly vendor specific usages that are expected to report a string descriptor index.

[Sigurd]

Hi,

We don't have any examples or code for this, but in theory I don't think there should be any reason why it will not work in a HID over GATT application. 

In this document, https://www.usb.org/sites/default/files/documents/hut1_12v2.pdf , it's mentioned at page 23:

 and there is an example on how a HID report map with this types of strings at page 148 in the document.