Long service UUIDs vs short service UUIDs

[Andrew Kohlsmith]

I'm working with the nrf51-app-ble-lbs demo from github. I notice that when I'm using BLE scanning apps, the VS service UUID is long (128 bits), whereas if I'm looking at other BLE devices around the house, they're all short (16 bits).

What causes this and is there any advantage/disadvantage to using long or short service UUIDs? I've also noticed the characteristic UUIDs are long on the lbs demo and short on the other devices.

[Lucas]

Hello Andrew,

I would suggest you look at page 9 of nAn-36. You can find it on the info page for the nrf51822 part. This document will go into a little detail about long vs short UUID's.

Essentially, the long ones are used for custom services/characteristics and the short ones are for BLE SIG services/characteristics.

There are disadvantages to it being longer. More data to transmit. Hard to fit the large one into advertisement packets.

Lucas

[Andrew Kohlsmith]

Thank you; I've been over that doc a hundred times and I can't believe I missed that.

[David Edwin]

You can also purchase a 16bit UUID from the Bluetooth SIG, if you are a Bluetooth SIG member in good standing. See www.bluetooth.org/.../sdo-16-bit-uuids