GATT Client & Server

[Brandon Kuhn]

Please can you help me with this fairly straight-forward technical query for a customer new to BLE.

Please can you advise which is the best way to structure the link in a customer situation as follows:

The customer has an automotive aftermarket product. They have a BT pod which they connect to the device on the car and then an app on a phone. The pod connects by UART, takes some bytes of data off the car and sends it over BT using the GATT profile to the phone. Change are made to the bytes to change settings and then the bytes are sent back through the pod to the unit. They used to do this over BT classic using SPP which was quite easy, but module has gone EOL so they are considering using BLE with the processor on the nRF52832 packing the data from the UART and sending over BLE with the GATT profile.

The customer would like to get a better understanding of how the GATT client & server works and which would you suggest to make the client and which would you suggest to make the server?

Thanks

Brandon

[Sigurd]

Hi,

SSP is a classic Bluetooth profile, and doesn't exist for Bluetooth low energy. Much of the philosophy with low energy is that you are not restricted to using the official profiles, compared to BR/EDR. It's very easy to create your own profile and proprietary service, to enable you to transfer data in sensible chunks instead of just cramming all kinds of data together in serial packages. The flexible profile architecture in BLE allows everyone to make their own customized profiles for their particular application.

That said, we have created a UART/Serial Port Emulation BLE service called Nordic UART Service (NUS) that is meant as an alternative to SPP, and it can be used as a starting point for implementing your own proprietary service. More information about NUS can be found here.

A tutorial on how to create a custom service with a custom value characteristic can be found here.

We have some BLE tutorials here, they are a little bit outdated, but their explanation about the BLE basic is still valid.

A introduction video to BLE can be found here.

The nRF5 SDK can be downloaded from here.

Documentation can be found here.

[Brandon Kuhn]

Thanks Sigurd - that's very helpful.