HID get report from a mac not as expected

Question

Hello again,
This time I am trying to read HID reports using bluetooth to get the state of the caps lock.
I know this should be super simple and its explained in the hid keyboard peripheral example using ble_hids_outp_rep_get. I am using a mac as a test machine and the report never becomes 0x02 (caps enabled). 
 Sadly I am unable to test it either using nRF connect due to the following: ˇ github.com/.../4 
 Can anyone confirm that this is the case and if so, assuming it works on windows, explain why mac behaves this way? 
 Thank you,
Yiangos

eekwils · Answer

I know this thread is 3 years old but I think I've found a solution to this issue if anyone else is coming across it.

When using the ble_hids_keyboard example from the SDK I was experiencing the same problem, I would receive a report from macOS but the value of the caps lock bit wouldn't change. As I developed my firmware further I added a consumer control report to the hid device descriptor which meant that I needed to explicitly add a report ID to both the keyboard report and consumer control report. After adding the report ID to the keyboard report the capslock functionality started working on macOS. I haven't had time to fully test that this was the change that did it but I pretty sure it was.

My report descriptor looks like this:

static uint8_t report_map_data[] = 
    {
        0x05, 0x01,       // Usage Page (Generic Desktop)
        0x09, 0x06,       // Usage (Keyboard)
        0xA1, 0x01,       // Collection (Application)
        0x85, 0x01,       // Report ID (1) <---- !!!!This is the bit I added
        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)

        0x95, 0x01,       // Report Count (1)
        0x75, 0x08,       // Report Size (8)
        0x81, 0x01,       // Input (Constant) reserved byte(1)

        0x95, 0x05,       // Report Count (5)
        0x75, 0x01,       // Report Size (1)
        0x05, 0x08,       // Usage Page (Page# for LEDs)
        0x19, 0x01,       // Usage Minimum (1)
        0x29, 0x05,       // Usage Maximum (5)
        0x91, 0x02,       // Output (Data, Variable, Absolute), Led report
        0x95, 0x01,       // Report Count (1)
        0x75, 0x03,       // Report Size (3)
        0x91, 0x01,       // Output (Data, Variable, Absolute), Led report padding

        0x95, 0x06,       // Report Count (6)
        0x75, 0x08,       // Report Size (8)
        0x15, 0x00,       // Logical Minimum (0)
        0x25, 0x65,       // Logical Maximum (101)
        0x05, 0x07,       // Usage Page (Key codes)
        0x19, 0x00,       // Usage Minimum (0)
        0x29, 0x65,       // Usage Maximum (101)
        0x81, 0x00,       // Input (Data, Array) Key array(6 bytes)

        0x09, 0x05,       // Usage (Vendor Defined)
        0x15, 0x00,       // Logical Minimum (0)
        0x26, 0xFF, 0x00, // Logical Maximum (255)
        0x75, 0x08,       // Report Size (8 bit)
        0x95, 0x02,       // Report Count (2)
        0xB1, 0x02,       // Feature (Data, Variable, Absolute)

        0xC0,             // End Collection (Application)

        //Consumer Control report
        0x05, 0x0C,       // Usage Page (Consumer Devices)
        0x09, 0x01,       // Usage (Consumer Control)
        0xA1, 0x01,       // Collection (Application)
        0x85, 0x02,       // Report ID (2)
        0x15, 0x00,       // Logical Minimum (0)
        0x25, 0x01,       // Logical Maximum (1)
        0x75, 0x01,       // Report Size (1)
        0x95, 0x01,       // Report Count (1)

        0x09, 0xCD,       // Usage (Play/Pause)
        0x81, 0x02,       // Input (Data, Value, Relative, Bit Field)
        0x09, 0xB5,       // Usage (Scan Next Track)
        0x81, 0x02,       // Input (Data,Value,Relative,Bit Field)
        0x09, 0xB6,       // Usage (Scan Previous Track)
        0x81, 0x02,       // Input (Data,Value,Relative,Bit Field)
        0x09, 0xE2,       // Usage (Mute)
        0x81, 0x02,       // Input (Data,Value,Relative,Bit Field)
        0x09, 0xE9,       // Usage (Vol Up)
        0x81, 0x02,       // Input (Data,Value,Relative,Bit Field)
        0x09, 0xEA,       // Usage (Vol Down)
        0x81, 0x02,       // Input (Data,Value,Relative,Bit Field)
        0x09, 0x6F,       // Usage (Brightness Up)
        0x81, 0x02,       // Input (Data,Value,Relative,Bit Field)
        0x09, 0x70,       // Usage (Brightness Down)
        0x81, 0x02,       // Input (Data,Value,Relative,Bit Field)

        0xC0
    };

And my output report now looks like this:

    #define OUTPUT_REPORT_INDEX   0
    #define OUTPUT_REP_REF_ID     1//<----!!! This must match the report id specified in the descriptor
    #define OUTPUT_REPORT_MAX_LEN 1

    p_output_report                       = &output_report_array[OUTPUT_REPORT_INDEX];
    p_output_report->max_len              = OUTPUT_REPORT_MAX_LEN;
    p_output_report->rep_ref.report_id    = OUTPUT_REP_REF_ID;
    p_output_report->rep_ref.report_type  = BLE_HIDS_REP_TYPE_OUTPUT;

    p_output_report->sec.wr               = SEC_JUST_WORKS;
    p_output_report->sec.rd               = SEC_JUST_WORKS;

I have no idea why specifying a report id would cause macOS to act differently but it seems it does.

I hope this can help anyone who's having this problem!

HID get report from a mac not as expected

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