What is the data exchanged during connection interval if there is no data to send?

[SumitS]

Hi,

I have set connection interval as 1.8s. But i have transmit data every 1 min. I noticed that BLE transmits data every 1.8sec. Can someone please tell me what is the data transmitted over BLE between Peripheral & Central when there is no data to transmit.

Thanks

[RK]

An empty packet each way. Required by the spec. You can turn slave latency up on your slave if you like so only the master will send every 1.8s, the slave will only send every now and again.

[SumitS]

No i cant increase my slave latency much as i need to communicate with an iOS app. By an empty packet you mean it will send Basic BLE packet but without any in it. Am i right?

[Stian Røed Hafskjold]

A connection packet consists of:

• Preamble (8 bit)
• Access address (32 bit)
• Header (16 bit)
• Payload (Data) (0...216 bit)
• CRC (24 bit)

It is required to send a packet every connection interval to keep the connection up (without slave latency). If you have no data to send, it transmits an empty packet. An empty packet is just like a regular connection packet, just with a 0 byte payload.