Multi-Central question

[bscdb]

I would like my BLE device to communicate with Desktop using HID service & with a phone using custom gatt service. I know its just adding one more service but is it possible to do it in one firmware image? Also how can the BLE device (in peripheral role) know whether the central is a Desktop or a phone? What should I include in the app running on Desktop/Phone?

[awneil]

Yes, it is possible for a firmware image to have multiple Services.

bscdb said:

Also how can the BLE device (in peripheral role) know whether the central is a Desktop or a phone?

Probably easiest for the Central to just use the Service it wants ... ?

[bscdb]

I was thinking more from battery point of view. Instead of sending data over both the services, the ble device can just send data over either one. But if thats not possible then I guess I'll just use both the services.

[awneil]

The Central would only enable the Service it requires ...

[bscdb]

Ohh. How does the central enable the service?

[Simon]

In order for the peripheral to send data to a central (computer or a phone), the central has to subscribe to notifications for a characteristic.

On the central side, the device has subscribe to notifications for a characteristics by writing 1 to the corresponding CCCD (E.g. the computer subscribes to the characteristics in the HID service)

On the peripheral side, you are then able to send data to the correct device by checking the CCCD value.

Best regards,

Simon