Communicate in BLE with NRF52 using Android

[Vivien]

Hi everyone,

I'm a beginner in Android development and BLE environment, and I want to communicate with the nRF52 card using an Android app. In fact I have to develop an access control, using the nRF52 board and an Android App.

For now I'm able to scan BLE device and pair the card with my app. Now I want to write on the card (maybe through a BLE characteristic), then compare this value and turn on a LED if this value is correct. My problem is that I don't know how to write on the card and where I would be able to retrieve the value written (on the card) to compute my comparaison. Thus I would like to know where a value written on a BLE characteristic would be stored ?

Thanks, Vivien

[Hung Bui]

Hi Vivien,

Please have a look at our example apps, such as the nRF UART app or the nRF Toolbox app. You can find how to do a write on a characteristic. The value of a BLE characteristic is stored in the Attribute table on RAM (could be in the Stack's RAM area or in the application's RAM area)

[Hung Bui]

Hi Vivien,

Please have a look at our examples the nRF5 SDK v.11. For example the experimental_ble_app_blinky where you can turn off and on an LED using an app (nRF Blinky) You can find the app source code here.

Note that we don't call sd_ble_gatts_value_get() to get the value of the characteristic to change the LED state but we catch the BLE_GATTS_EVT_WRITE event to change the LED state.