https://devzone.nordicsemi.com/f/nordic-q-a/12845/using-the-same-characteristic-uuid-in-multiple-servicesI have a demo(s110) set up with some custom services, and in them custom characteristics. The services each relate to a specific sensor element on my device, so have a mostly shared structure of the service, i.e. I re-use characteristic UUIDs across differenten-USTelligent Community 13Tue, 29 Mar 2016 11:04:22 GMThttps://devzone.nordicsemi.com/thread/48850?ContentTypeID=1Tue, 29 Mar 2016 11:04:22 GMT137ad170-7792-4731-bb38-c0d22fbe4515:7f1103ca-307a-4543-b4eb-78933937fa0dSensors<p>Accidentally converted that to answer. Oops.</p> <p>I&#39;ve realised you have made a good point though. On checking the CCCD values it seems like the only one that actually changes is that of the one I activate. In the Nordic MCP app for my phone (which I&#39;m using as the central) when I tap to turn on notifications, it changes all the notification icons. Pretty confusing.</p> <p>Must be a bug in the app itself.</p> <p>Good to know that I can reuse Characteristic UUIDs though, thanks.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/48849?ContentTypeID=1Tue, 29 Mar 2016 10:43:53 GMT137ad170-7792-4731-bb38-c0d22fbe4515:04350d0f-10a8-461d-b37b-0f30cb1c7de3Petter Myhre<p>As far as I know, it shouldn&#39;t be necessary to have unique characteristic UUIDs. After service discovery the ATT operations are referenced with the attribute handle, so this doesn&#39;t make sense to me. Could you explain to me how you check that both CCCDs are actually changed? Have you tried reading them to check that they are actually 0x0001? What is your central device? Do you have sniffer trace where this happens? Or could this be related to how you handle the write event (BLE_GATTS_EVT_WRITE) in ble_evt_dispatch()?</p><div style="clear:both;"></div>