Need support on Wireless Node Application

[iotracking]

Hello Nordic Team,

We are looking for a solution for time synchronization in wireless nodes and communication among the nodes. Nordic has various solutions on different-different protocol i.e., BLE, BLE mesh, Zigbee, OpenThread. We come to Nordic support team to get appropriate solution as per our application requirement.

Application Requirement: In the system, there are several nodes in which one node will be the Master and the other nodes will be the Slave. Each node has some sensors and needs to send the sensors' data to the particular node(this node can be in the range of sender node or not in range) where the mobile phone is connected. A mobile application will collect all this information and run some analysis. To run the analysis, all nodes must be time synchronized with the master node and time synchronization accuracy requirement is 10 milliseconds. Master node should get notification such as all nodes are synchronized.

Let say, we have 6 nodes in one system, placed at every 200 m distance. All the nodes should get synchronized at some time interval i.e., 60 seconds. Mobile application is connected with last node, placed at 1000 m distance from Master node at 0 m.

Based on our application, we have some queries mentioned as below.

1. How can we achieve Time accuracy to 10 ms among all the nodes ?

2. Is it possible to run Time synchronization and nodes communication together on single Radio?

3. Which protocol is suitable to achieve our application ?

Our annual production quantity is approx. 10K. It would be good if you could connect FAE to us.

Highly appreciated if we could get some response.

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Thanks & Regards !!!

[AHaug]

Hi,

Here's an update to let you know that we will be looking into your questions and continue from your previous case, Timesync and BLE mesh functionalities not working together on nRF52840-DK board . Do however note that it is Christmas Holidays here in Norway so we will unfortunately not be able to look into this before January

In general I believe I have given you an answer for this in the previous case for how you can do this, but as it goes for specific numbers you will most likely have to do some experimentation with your own firmware on your own hardware to verify any numbers in your hypothetical configuration. I will check in with my colleagues next week to see if they have anything else to add to this.

Our annual production quantity is approx. 10K. It would be good if you could connect FAE to us.

Please reach out to your regional sales manager to talk about any potential needs and requirements. Let me know if you need their contact information.

Kind regards,
Andreas

[iotracking]

Hello Andreas,

Thanks for your response.

The previous post is mainly on the nRF52840 chipset, which we have already evaluated with 5 nodes and shared the test results. With nRF52840, the problem is BLE mesh and the wireless time synchronization method needs Radio continuously at the same time. So what happens is sometimes time synchronization takes so much time to synchronize among 5 nodes and sometimes the mesh packet gets lost (tried increasing the retry count as well). It would be good if we could resolve these limitations on nRF52840.

Now, nRF5340 supports dual-core whereas nRF52840 supports single-core. As it supports dual-core, so is it possible to resolve the above limitations with it?

Also, please share the regional sales manager's contact information as well.

Thanks & Regards !!!

[AHaug]

Hi,

I've sent you a PM with the RSMs e-mail so you can reach out to them through that.

I've discussed your question and configuration with my colleagues and we agree on that using the nRF5340 will not resolve the synchronization for a single radio device. The answers below here will also cover the latest question you had in  Timesync and BLE mesh functionalities not working together on nRF52840-DK board  

1. How can we achieve Time accuracy to 10 ms among all the nodes ?

From your query I see that you've thought about this already in your initial analysis, but nonetheless we believe it is the best option is to examine and investigate your design to figure out how much of the radio each of your components uses. This will be a tough challenge as the distance between devices is significant and will cause both retransmissions due to packet loss and a need to synchronize the devices fairly often.

It is hard to state if it is possible at all to perform what you want with the range in between the devices being so large with the constraints you've put.

2. Is it possible to run Time synchronization and nodes communication together on single Radio?

Again it will depend on how often you need to do synchronization and the protocol you choose. 

If you refer to "running synchronization over Bluetooth Mesh", then the answer is no. If you're referring to "Doing synchronization in parallell with a BT Mesh network", then the answer is maybe.

3. Which protocol is suitable to achieve our application ?

You will need to use something with both long range and that is designed to w.r.t time synchronization. Unfortunately BLE Mesh, Zigbee and OpenThread is not the best due to the constraints in your network, so instead you should look into a protocol using BLE connectivity such as Fruitymesh or another protocoll based on timing. 

Kind regards,
Andreas