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]

It came to my attention earlier this month that the version used with nRF Connect is actually using 1M baud, despite that the default in the connectivity patch for pc-ble-driver is 115k. Changing to 1M should give similar performance as for nRF Connect.

[Frederik]

Thanks Terje, just tested switching to 1M - seems to work now with 3 devices - not sure why - have tested it before and driver failed to initialize...

anyway now the 4 devcie connection problem is kicking in ;) Can you have a look at it ?

[Frederik]

So as shown in the other post: setting MAX_PEER_COUNT to 6 seems to work for 4 devices.

Sadly nearly the same problem. Now:

• 3 peripherals sending @ 100Hz -> 3x 100Hz @ UART (pc-ble-driver)
• 4 peripherals sending @ 100Hz -> 4x ~75Hz @ UART (pc-ble-driver)

So there seems to be a bottleneck in the device firmware / controller.