Timesync and BLE mesh functionalities not working together on nRF52840-DK board

[iotracking]

Hello,

Our application is to create BLE mesh network with multiple nodes, each node is having sensor. Each node will send sensor value and timestamp over the mesh network and there is a mobile application connected with one destination node which is collecting all information for further analysis. For timestamp, it is required to synchronized the time value in milliseconds in all the mesh nodes. So all nodes are having same timer value.

nRF Connect SDK version: v2.2.0

Hardware: nRF52840-DK Evaluation board

For BLE mesh, we are taking reference of ble_peripheral_lbs_coex example (available in samples\bluetooth\mesh\). It is working fine with multiple nodes in standalone.

To synchronize the time, we are using Timesync example same as mentioned in one of the post ( Wireless timer synchronization among nRF5 devices ). It is working fine with multiple nodes in standalone. 

Now, as per our requirement we need both as single application so we integrate time sync code into BLE mesh example code and compiled successfully. After integration, we are observing MPSL_TIMESLOT_SIGNAL_BLOCKED message continuously on serial terminal and time synchronization is not working. During this, mesh packet is able to transmit and receive on the mesh nodes.

We increased BLE mesh scan interval from 30 ms to 2000 ms. After this, Timesync is started working but BLE mesh stopped working.

Is there any way to work both functionalities(BLE mesh and Timesync) simultaneously? or is there any other way to synchronize the time(in milliseconds) on all the nodes over mesh?

It would be highly appreciated if we could get some response.

Thanks !!!

[AHaug]

Hi

iotracking said:

1. Does nRF connect SDK support Star or Mesh network topology for Zigbee protocol? I didn't find any information about star topology.

Both of these configurations are supported, which is mentioned in the topologi section of the Zigbee documentation. it only depends on how you commission the devices into the ZigBee network, i.e what parent a device should have and/or if the devices are a part of a group (for instance a light bulb group for the kitchen in a house).

iotracking said:

1a. If NCS supports Zigbee mesh then it will be a similar case that we have implemented with BLE and BLE mesh concurrently. Am I understood correctly? If not, then how Zigbee mesh is different than BLE mesh?

Somewhat yes, but not quite. I won't be able to explain it completely in detail, as that would require me to dive extremely deep into the specification to find the difference, so I will only briefly explain it here and recommend you to investigate the specs and the documentation and samples for Zigbee and Mesh  in more detail.

You can draw parallels between the two protocols due to similarities but there are differences, the most notable of this being that Bluetooth Mesh is using what is called "Managed flooding", (mentioned in section 2.2 in the Mesh profile specification) while Zigbee uses "Full routing" when transmitting data. There is also a difference in the number of supported devices in the networks (~32k for Mesh and ~64k for Zigbee), range, power consumption and area where it is "recommended" to apply the two different protocols.

iotracking said:

2. Do we need a Zigbee coordinator to manage the ZigBee network?

Yes, you will need a coordinator. Every Zigbee network has a trust center, which is typically centralized meaning that the trust center is in the coordinator. The coordinator manages the commissioning of new devices into the network as well as existing devices in the network. There is an option (that is not typically recommended) which is a decentralized trust center. You can read more about this in the Zigbee specification.

iotracking said:

Will Zigbee coordinator implementation be handled by nRF52840 chipset i.e., Flash and RAM memory?

Yes, you can see the Zigbee samples on developer.nordicsemi.com where you will find the Network Coordinator sample. The nRF52833 is also a supported device for this sample, but do note that this sample does not take DFU in consideration.

Kind regards,
Andreas

[iotracking]

Hello Andreas,

Thanks for all your support. We are still looking for reliable solutions.

I read about nRF5340 chipsets with dual processors, one processor can handle only the application part and the other softdevice part(radio).

Is it feasible to achieve 10 ms time accuracy among all the nodes i.e. 10 nodes, using the time synchronization method and BLE mesh to communicate with all the nodes simultaneously?

Thanks & Regards !!!

[AHaug]

Hi,

I see you've created a new case for theese questions in  Need support on Wireless Node Application. I will continue the discussion in that case. Do however note that its Christmas holidays in Norway so we will not be looking deeply into the case before January.

I will mark this case as closed and come back to you in your latest case

Kind regards,
Andreas