BLE Characteristic Value - BLE blinky example

[Akash.S]

Hi,

On button press, the button handler event calls the "ble_lbs_on_button_change" function which sends notification to the BLE client.

uint32_t ble_lbs_on_button_change(uint16_t conn_handle, ble_lbs_t * p_lbs, uint8_t button_state)
{
    ble_gatts_hvx_params_t params;
    uint16_t len = sizeof(button_state);

    memset(&params, 0, sizeof(params));
    params.type   = BLE_GATT_HVX_NOTIFICATION;
    params.handle = p_lbs->button_char_handles.value_handle;
    params.p_data = &button_state;
    params.p_len  = &len;

    return sd_ble_gatts_hvx(conn_handle, &params);
}

The value of the button state parameter in the function call is either 0 or 1 (0 corresponds to button press and 1 corresponds to button release).

The value shown in the client side is "Button pressed" and "Button released"

Can you tell where the strings corresponding to the button states added in the SDK?

[Susheel Nuguru]

Can you tell where the strings corresponding to the button states added in the SDK?

 I think there are no strings (Button Pressed/Button Released) in the SDK code in itslef. I think it is the nRF Connect mobile APP that is doing this magic of converting 0/1 value on that characteristic to Button Pressed/Button Released

[Akash.S]

Thank you Susheel.

I tried sending values other than 0 and 1, and in the app it shows "invalid value". Just wanted to confirm if this case is also a consequence of nRF connect mobile app implementation.

[Susheel Nuguru]

The notifications that are sent from the LBS client in  components\ble\ble_services\ble_lbs\ble_lbs.c\ble_lbs_on_button_change is button_state which is one of the following from app_button.h file

So I think sending 0 and 1are valid values to be written. Probably you are not sending them as hex/dec numbers and sending them as ASCII?