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

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

AHaug — Wed, 27 Dec 2023 13:13:12 GMT

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

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

iotracking — Sat, 23 Dec 2023 03:44:13 GMT

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 !!!

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

AHaug — Thu, 21 Sep 2023 08:37:14 GMT

[quote user="iotracking"]1. Does nRF connect SDK support Star or Mesh network topology for Zigbee protocol? I didn't find any information about star topology.[/quote]

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).

[quote user="iotracking"]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?[/quote]

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.

[quote user="iotracking"]2. Do we need a Zigbee coordinator to manage the ZigBee network?[/quote]

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.

[quote user="iotracking"]Will Zigbee coordinator implementation be handled by nRF52840 chipset i.e., Flash and RAM memory?[/quote]

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

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

iotracking — Thu, 21 Sep 2023 03:30:51 GMT

Hello Andreas,

Thanks for your detailed response.

I have some queries regarding Zigbee mentioned below.

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

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?

2. Do we need a Zigbee coordinator to manage the ZigBee network? Will Zigbee coordinator implementation be handled by nRF52840 chipset i.e., Flash and RAM memory?

We will try the example that you mentioned and will let you know if we have more queries.

Thanks & Regards !!!

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

AHaug — Tue, 19 Sep 2023 12:05:09 GMT

Hi,

Glad to hear that you managed to implement the features you wanted even though the results weren't satisfying

[quote user="iotracking"]1. Run BLE and Zigbee concurrently on the nRF52840 chipset. Time synchronization and BLE peripheral will be run on BLE and node communication will be run on Zigbee. We know that Radio is going to share between 2 protocols but we feel that Zigbee will be active only during node communication, not like BLE mesh.[/quote]

I recommend you to have a look at the multiprotocol support page at https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/protocols/multiprotocol/index.html as well as the Zigbee light switch sample section regarding BLE multiprotocol support https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/samples/zigbee/light_switch/README.html#multiprotocol-bluetooth-le-extension-assignments

The Multiprotocol page should tell you about some items to consider while the lastly mentioned sample should showcase how this is done in a ZigBee application in practice. Depending on the criteria your application needs, you may find this option to be suited to your application.

[quote user="iotracking"]2. Run the BLE stack on the nRF52840 chipset and run the Zigbee stack separately on another nRF52840 chipset. In this case, 2 chipsets are required on a single system.[/quote]

I'm not too familiar with this configuration so you might have some more luck by raising the question in a new ticket but my thoughts are that you will need to use some coexistence such as https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrfxlib/mpsl/doc/cx.html to avoid interference. Note that the link I posted is for multiple radios but only with one application/SoC

Let me know if this answers your initial questions and please

Kind regards,
Andreas

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

iotracking — Mon, 18 Sep 2023 14:00:23 GMT

Hello Andreas,

We have integrated all 3 functionalities, Time Synchronization + node communication over BLE Mesh + BLE peripheral, and tested with 5 nrf52840 DK boards on the field. We have tuned the BLE scan and advertisement interval for all 3 functionalities and it started working. Now, we observed some of the limitations during so much testing on the field, mentioned below. We tested with 5 DK boards; the distance between each node is 10 meters.

1. Time synchronization takes random time to get synchronized with all 5 nodes. As per our testing, we observed a minimum time of approx. 1 minute and a maximum time of approx. 5 minutes. Maximum time can be beyond 5 minutes. This is not acceptable in our case.

2. Sometimes mesh packet takes more time to travel from 1st node to 5th node.

To overcome these limitations, we are thinking of 2 different solutions and we need your suggestions.

1. Run BLE and Zigbee concurrently on the nRF52840 chipset. Time synchronization and BLE peripheral will be run on BLE and node communication will be run on Zigbee. We know that Radio is going to share between 2 protocols but we feel that Zigbee will be active only during node communication, not like BLE mesh.

2. Run the BLE stack on the nRF52840 chipset and run the Zigbee stack separately on another nRF52840 chipset. In this case, 2 chipsets are required on a single system.

We prefer to go with solution number 1. Please share your thoughts.

Looking forward to your response.

Thanks & Regards !!!

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

AHaug — Wed, 14 Jun 2023 07:51:59 GMT

Happy to help!

Let me know if it works out for you

Kind regards,
Andreas

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

iotracking — Wed, 14 Jun 2023 01:44:36 GMT

Hello Andreas,

Thanks for your detailed response. We are working on it.

Thanks & Regards !!!

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

AHaug — Thu, 08 Jun 2023 17:43:17 GMT

Hi,

[quote user="iotracking"]1) Can you point us out the code where we can see/change priority in Timesync code?[/quote]

Timeslot priority is set here:

[quote user="iotracking"]2) Same, point us out priority configuration in Mesh and Peripheral coex example code?[/quote]

It's a bit different w.r.t priority In NCS when you combine BLe and Bluetooth Mesh. The two runs in parallell, i.e you set up Mesh, and then you set up the advertising/connection/whatever you intend to use BLE for, and then it becomes scheduled so that Mesh is used whenever there is "surplus radio capacity" for Mesh

With the two latest versions of NCS it is (to my understanding) set up such that scanning uses the free, available radio time in between other activity, so you will get close to 100% radio usage when you combine Mesh with BLE.

I would recommend you to have a look at developer.nordicsemi.com/.../scheduling.html for the full documentation for how the SoftDevice Controller does its priority and scheduling

[quote user="iotracking"]3) Is it feasible if we can send mesh packet and timesync packet on different RF channel?[/quote]

When a timeslot is granted, you can use the radio however you wish within that timeslot. That includes using different frequencies.

[quote user="iotracking"]4) Is it feasible if we can combine timesync packet with mesh interval packet which will send during mesh interval?[/quote]

I'm not quite sure if I understand 100% what you want to do which leads you to ask this question, but if the motivation is to put something proprietary on top of the existing Mesh traffic, then the answer is no. By doing so you will break the qualification that the Mesh stack in NCS has, and you can't "expand on it" by adding another feature. In addition there are no general "timing" in Mesh, so you would not be able to time it so that you can fit within an interval or.

We would recommend you to choose a frequency for sync messages and let the Mesh stack get the rest of the time. A guesstimation for for how much time you could give the timesync part of the application is around 10% of the time. Do note with a disclaimer that you might find better results with other windows, but the I believe that 90% of the time available should be sufficient for the Mesh stack.

Let me know if this answers your questions,

Kind regards,
Andreas

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

iotracking — Wed, 07 Jun 2023 07:23:15 GMT

Hello Andreas,

Thanks for you response and detailed information. I have some queries. Please try to address them.

1) Can you point us out the code where we can see/change priority in Timesync code?
2) Same, point us out priority configuration in Mesh and Peripheral coex example code?
3) Is it feasible if we can send mesh packet and timesync packet on different RF channel?
4) Is it feasible if we can combine timesync packet with mesh interval packet which will send during mesh interval?

Thanks and Regards !!!

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

AHaug — Mon, 05 Jun 2023 12:57:48 GMT

Hi,

I brought up the questions with the blog author and the Mesh team and this is what we landed on

As far as we know we don't have any official or unofficial support for how to get this to work in NCS, but it might be possible to create a priority solution based on the method in the blog post.
One item that might cause some issues is the question about how much the PRX (the device that listen to the time master) has be in RX. The timesync code as it is now is not optimized w.r.t. radio time. The sender does not use the radio too much, but the receiver tries to allocate as much time as possible to listening for sync packs. This will conflict with Mesh due to Mesh also wanting to be as much as possible in RX
With regards to the time resolution. Theoretically it should be sufficient to send one pack roughly every second to achieve 1ms sync. But this will depend on that the sync sender and receiver gets enough radio time to exchange one sync message.

I believe this should answer your questions about getting both functionalities to work simultaneously. In short, it might be possible but we don't have any support for Mesh and timesync simultaneously in NCS out of the box

Let me know if this answers your question

Kind regards,
Andreas

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

iotracking — Sat, 03 Jun 2023 08:19:11 GMT

Hello Andreas,

Thanks for your response and efforts. Looking forward for your response.

Thanks !!!

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

AHaug — Fri, 02 Jun 2023 13:46:27 GMT

Hi,

We've picked up your case and are looking into the issue, however I don't have anything constructive for you as of now (waiting for some input about the topic from the Mesh team). I will get back to you early next week if we have any existing ways or samples that integrates BLE Mesh and Timesync simultaneously

Apologies for the inconvenience

Kind regards,
Andreas