Questions about the distance measurement mesh model

RE: Questions about the distance measurement mesh model

AndyM — Tue, 31 Jan 2023 22:24:58 GMT

Update

Got it to work, Can use mesh dm in the shell and measure distance between 2 nodes

Here is what I had to do i

1. proj.conf

CONFIG_BT_MESH_DM_CLI=y

CONFIG_BT_MESH_DM_SRV=y

2. Add dm server and client to model composition

struct bt_mesh_model _vnd_models[] = {

// your vendor models

// Distance measurement models.

BT_MESH_MODEL_DM_CLI(&_dm_client),

BT_MESH_MODEL_DM_SRV(&_dm_srv)

};

// config client.used for provisioning via shell

struct bt_mesh_cfg_cli _config_client;

static struct bt_mesh_model _root_models[] = {

BT_MESH_MODEL_CFG_SRV,

BT_MESH_MODEL_CFG_CLI(&_config_client),

};

static struct bt_mesh_elem _elements[] = {

BT_MESH_ELEM(0, _root_models, _vnd_models),

};

3. I use mesh shell to provision. Added the following commands

bind dm client model to node address

mesh models cfg model app-bind <node addr> 0 0x000C 0x0059

bind dm server model to node address

mesh models cfg model app-bind <node addr> 0 0x000B 0x0059

NOTE

0x0059 is Nordic BLE ID. Must bind these models using Nordic ID not your company ID

Otherwise bind fails

Provisioned 2 nodes

Now can do the following in the mesh shell

mesh init

mesh target dst <node address>

mesh models dm start 1 (MPCD mode) <other node addr>
Get this back

Status: Success (err: 0)

Entry number: 1
Mode: MCPD
Quality: 0
Error Occurred: 0
Address: 0X0001
Best distance (cm): 60
IFFT distance (cm): 60
Phase slope distance (cm): 196
RSSI open space distance (cm): 891

NOTE

The measurement takes about 2 seconds ( 1 minute 51-52 seconds)

This is for 2 devices within BLE range

Seems a bit long

RE: Questions about the distance measurement mesh model

AHaug — Fri, 27 Jan 2023 13:34:38 GMT

Hi,

I'm waiting for some input from the Mesh developers. Hopefully I hear back from them next week.

Apologies for the inconvinience,

Kind regards,
Andreas

RE: Questions about the distance measurement mesh model

AndyM — Thu, 26 Jan 2023 14:06:12 GMT

Andreas

I'm still stuck with my effort to incorporate the DM mesh model into my application and need help there. I added both client and server models to my mesh model composition but cannot even use the mesh DM shell sample to start a measurement - it returns an error. There is an entry above with the details but I can provide more if that's not enough. Thank you

RE: Questions about the distance measurement mesh model

AHaug — Thu, 26 Jan 2023 08:41:01 GMT

Hi,

[quote user="AndyM"]Can you clarify - does this apply to the ranging or synchronization phase or both?[/quote]

This will be during both phases. 10 seconds sounds like a long time to receive the measurement results. I will clarify this number with the Mesh team and ask them if the results sounds within expectations

Kind regards,
Andreas

RE: Questions about the distance measurement mesh model

AHaug — Thu, 26 Jan 2023 08:39:54 GMT

Hi,

I've noted that you're also interested in a sample, but unfortunately the same reply with regards timeline will go here as well. I will let you know if and when I get it done.

Kind regards,
Andreas

RE: Questions about the distance measurement mesh model

AndyM — Wed, 25 Jan 2023 14:49:01 GMT

[quote userid="107683" url="~/f/nordic-q-a/95646/questions-about-the-distance-measurement-mesh-model/405011"]node cannot participate in the mesh communication during DM ranging. [/quote]

Can you clarify - does this apply to the ranging or synchronization phase or both?
In my experiments it can take 1-10 seconds to receive the measurement result. Farther nodes tend to take longer to measure

RE: Questions about the distance measurement mesh model

markibi — Wed, 25 Jan 2023 14:25:47 GMT

Hi Andreas,

[quote userid="107683" url="~/f/nordic-q-a/95646/questions-about-the-distance-measurement-mesh-model/405011"]

Currently we don't have any official samples planned. I will look into it and see if I can create an unofficial sample, but I can not guarantee anything w.r.t. time horizon and/or if it ever will be done.

[/quote]

Im also working in a bt mesh project and we need to use the distance measurement mesh model, even if the API is clear as a beginners we have some complications, then im also interested if either an official or unofficial sample is available.

I thank you in advance,

Kind regards,

Mehdi - Firmware engineer

RE: Questions about the distance measurement mesh model

AndyM — Mon, 23 Jan 2023 14:12:13 GMT

I was able to get around error -125 by setting the client->model->pub->addr to the unicast address of the node that initiates the measurement - now get error -22

RE: Questions about the distance measurement mesh model

AHaug — Thu, 19 Jan 2023 12:56:12 GMT

Hi,

I am unfortunately out of office until next week, so there will be some wait time. I will get back to you earliest then.

Kind regards,
Andreas

RE: Questions about the distance measurement mesh model

AndyM — Wed, 18 Jan 2023 22:40:27 GMT

Update. Used mesh dm client in mesh shell. Get same error -125

The dm client is in the composition
~$ mesh models dm instance get-all
Model instance found at addr 0x00C8. Element index: 0

Please advise

RE: Questions about the distance measurement mesh model

AndyM — Wed, 18 Jan 2023 19:02:33 GMT

Thank you

Having trouble incorporating DM mesh into my application.

I already have several vendor models, so I added

BT_MESH_MODEL_DM_CLI(&dm_client) and

BT_MESH_MODEL_DM_SRV(&dm_srv) to my model composition

When I call

bt_mesh_dm_cli_measurement_start() I get error -125 (EADDRNOTAVAIL)
Indeed the dm_client->model->pub.addr is 0

What should it be set to ?
Would be great to get a working sample with instructions how to provision

Thanks

RE: Questions about the distance measurement mesh model

AHaug — Mon, 16 Jan 2023 11:55:08 GMT

Hi,

Here is the result of the conversation I had with the Mesh developers.

[quote user=""]Do you plan to add a sample how the DM model should be used? That would very helpful[/quote]

[quote user=""]It seems that simply calling this API every time a scan packet arrives is going to overwhelm the mesh network. On the other hand it would be great to receive more than one measurement so averaging can be applied. What's your recommendation on how frequently should bt_mesh_dm_cli_measurement_start API be called?
[/quote]

We imagine distance measurement to be used not so often. Since, mesh nodes (such as lights) are often static, this feature could be useful during initial deployment of the network to find out topology of the network. At that time feature can be used to map-out the whole network and relative positions of the devices. You need to be aware that when distance measurement is being done the node cannot participate in mesh network operation as distance measurement library takes control of the radio to do the measurement. After network is deployed, distance measurement can be done say once in a day, or only where there is change in the network (like replacing devices). If the devices move around, DM can be triggered when, for example, accelerometer detects the movement. It really depends on the use case and imagination.

It is up to you as a developer to decide how to use the function calls to suit your applications/designs needs, but as mentioned there are limitations such as the operation node cannot participate in the mesh communication during DM ranging.

[quote user=""]

There is an API bt_mesh_dm_cli_results_get() which returns the measurement results.

However the results are available in the bt_mesh_dm_cli_measurement_start() callback.
Can you clarify when this function should be called?

[/quote]

bt_mesh_dm_cli_results_get() allows client to fetch several past measurements from the server at later point.

bt_mesh_dm_cli_measurement_start() will start the measurement and provide results for 'that' measurement.

Let me know if this answers your questions!

Kind regards,
Andreas

RE: Questions about the distance measurement mesh model

AHaug — Fri, 13 Jan 2023 13:38:26 GMT

Hi,

I will ask the Mesh developers about your questions and if we've planned a sample, so I'll get back to you when I hear from them

Kind regards,
Andreas

RE: Questions about the distance measurement mesh model

AndyM — Thu, 12 Jan 2023 16:05:37 GMT

One other thing
There are 2 API's in the DM library

nrf_dm_calc() and

nrf_dm_high_precision_calc()
It would be great to have a parameter to control which one is used