What is the difference between a BLE central reading from a peripheral versus a peripheral notifying the central in term of resources drained?

[helpme]

Suppose a BLE central needs to get sensor data from 10 peripheral sensors. Given that there is a limit to the number of connections a BLE central can have, is it better for the central to read from peripheral because it uses lesser resources compared to notify?

[Hung Bui]

@helpme: Could you give me more information on why you think read command would use less resource compare to notify ?

As far as I know, sending notify is more efficient than read command when thinking of the number of packet needed to send data (1 packets vs 2 packet).

The only advantage of read command I can think of is that the client (central) doesn't have to wait for notification but has control of when to get it.

[EDITED] Another advantage of using notify is to avoid the delay by slave latency. The peripheral can wake up in the middle of the latency sleeping period to send notification, when with read, the central have to wait until the next wake up of the latency sleeping period to get the data which only comes on next connection event after the read command.

[Hung Bui]

Well, you don't really need to keep the connection to be always on to receive notification. You can simply connect, wait for notification and disconnect right after that.

If you have bonded with the device, you don't have to enable CCCD on every connection. So you can configure the peripheral to send the notification right after it get connected then can immediately disconnect. I think it's the most efficient way of transmitting small data when remaining in low power.