1. You need to ensure at least one characteristic is allowed to send Notifications / Indications in your peripheral.
2. Your peripheral must make a call to GATTServApp_ProcessCharCfg() when the characteristic value to notify is changed
2. After establishing a connection, the central device needs to write the Characteristic Config value of the Characteristic to enable notifications for that central device.
3. Your central device must handle the Notify / Indicate event and process the data however you require