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

[Frederik]

Hi Terje,

100 HZ = 100 packets/s with 18bytes packetsize

CI 30 = 37,5ms

=> 100 packets / (1s / 37,5ms) => ~ 3,76 packets/CI

Total payload data per device per second = 18byte * 100/s = 1800 byte/s

So with 3-4 Packets / CI can you estimate how many devices I could connect?

(I will also check the link you mentioned)

Currently the whole nRF52 is a backbox for me - I just see less packets at the UART in the end and know that our transmitters are sending all packets (tested with another reciever). Thats why I assume I have to optimise the firmware somehow to recieve more than the 3,5 devices, e.g. RAM management, UART DMA transfer,... can you point in the right direction?

Also can you confirm that the nrf Connect included firmware is based on nRF5_SDK_XXX\examples\connectivity\ble_connectivity\pca10040\ser_s132_hci?

regards Frederik