RE: how are keyboard key release events sent in example code?

Håkon Alseth — Wed, 12 Nov 2014 15:32:40 GMT

Hi,

This example is a bit complex, especially when it's only purpose is to say "hello" via button press.

First off, you will get an interrupt when the button is pressed, triggering function "button_event_handler", which saves which byte is currently being sent (p_key), and passed on to function send_keys().

Send_keys() will send, over-the-air, the first ASCII letter packed into a HID-acceptable format, which is done by calling "send_key_scan_press_release()".

If this function returns w/o errors, you will queue a "release key" (all zeros) via function "buffer_enqueue()", and then it'll return.

Once the initial ASCII byte is successfully transferred over-the-air, you will get a event back from the SoftDevice, BLE_EVT_TX_COMPLETE in function on_ble_evt(), which then sends the previously enqueued release keys.

If you are developing a keyboard application with the nRF51x22, I would recommend that you look at the nRFready Desktop 2 reference design and how the scanning of the keyboard matrix is done there. The ble_app_hids_keyboard example does not give any insight towards setting up a keyboard matrix. It's purpose is to show the setup of the HoG (HID over GATT) profile as a keyboard.

Cheers, Håkon