Optimising for serialisation throughput?

[Frederik]

Hi, we are currently testing the nRF52 DK as a reciever for several BLE devices.

For a fist test we implemented some datarate measuring in the:

PC -> nrf Connect -> Bluetooht Low Energy App

The device firmware version is 1.1.0 (is suppose it not the newest from SDK 13.1.0?)

The datarate for 1 devices is 100Hz (18 bytes/package) @ ConnectionInterval: 30

We currently notice:

• 3 connected devices = 3x 100% Datarate

• 4 connected devices = 3x 100% datarate, 1x 50% datarate

• 5 connected devices = 3x 100% datarate, 2x 50% datarate

Baudrate of nrF Connect App is at 1000000. Should be way sufficient.

What is the limitation here? Can the firmware be optimized?

Regarding number of connections: As we currently know RAM is a critical value for the number of connection a device can hold. The latest SDK states to support up to 20 simultanious connections. Does that mean that value refers only to BLE5? Waht is it for SDK 13.1.0? Even im sure we wont be able to conenct 20 devices with that datarate cause of BLE limitations - what would be the expected number we can connect with full datarate with the serialized host?

regards Frederik

[tesc]

What do you mean by 100Hz data rate? You also write connection interval of 30 (ms) and 18 bytes/packet. How many packets per connection interval?

There is some overhead (due to serialization) and latency (at multiple points from the pc to the connectivity nRF) when using nRF Connect or any other pc-ble-driver based application, where you will see bottlenecks.

If you have a central connected to many peripherals with the same connection interval on the connections, then the events are scheduled as shown in Figure 3 in the Connection timing as a Central section of the SoftDevice specification. How many peripheral connections will fit depends on connection interval, packet size and number of packets per connection event.