Apple Media Service

RE: Apple Media Service

wiz0911 — Wed, 10 Jun 2020 13:40:01 GMT

Hi, thischier

I have the same problem , I use sd_ble_gattc_read() get the entity attribute data.the offset of this function value not worked.

How did you solve it and could you tell me how to solve it .

Thanks

RE: Apple Media Service

bjorn-spockeli — Fri, 01 Feb 2019 15:50:55 GMT

thischier: We'll continue the discussing in the private case.

Best regards

Bjørn

RE: Apple Media Service

thischier — Fri, 25 Jan 2019 13:06:49 GMT

Hello Runar

No worries about the late answer. I had other project to work on...

I saw the message sequence chart and tried to complete my project accordingly. Unfortunately I always get the same data when I call sd_ble_gattc_read(handle, offset).

The first call when I will read the entity attribute, I call sd_ble_gattc_read for the current connection handle, the handle of the characteristic and an offset of 0. When I get the first read response back, I check if the length of the data corresponds to the MTU size. If its >=, I assume that there are more data to read and I call sd_ble_gattc_read() for the same connection and char handle and the offset is the previous used offset (0) and the length of the received data. But even then I get the exact same data.

I added my project to my post, would be great if you could have a look on it.

Button configuration:

Btn1: Activate Entity Update

Btn2: Change the Entity Attribute (Artist -> Album -> Title -> Duration -> Artist -> ...)

Btn3: Call Entity Attribute Read (where I will read the truncated data manually)

I also included a small log file where you can get directly the result of my last test...

Many thanks in advance.

/thierry

devzone.nordicsemi.com/.../ble_5F00_ams_5F00_c_5F00_long_5F00_read.rar

RE: Apple Media Service

run_ar — Wed, 23 Jan 2019 11:26:55 GMT

Hi,

I am sorry for the late answer. Did you check the message sequence chart? Variant #2 shows how to us the offset to read the rest of the characteristic.

RE: Apple Media Service

thischier — Mon, 14 Jan 2019 10:11:22 GMT

Hello Runar

Thanks for your message.

I finished more or less the complete service.

When I start the example, I'm connecting to the device, bond, search for the AMS, assign all handles, enable the notifications (remote command and entity update).

I can also write to the remote command to play/pause a song, change the volume, change the track and so on.

I'm also able to register for different entity updates (for example artist, album and track of the track entity).

What's left is the multiple read functionality.

When I get a notification on the entity update characteristic, I receive

EntityID
AttributeID
EntityUpdateFlagTruncated
Value

If the EntityUpdateFlagTruncated is 1, it means that I didn't get the complete value of the attribute and that I need to read it out manually. This happens when the data size is bigger than 1 BLE packet (MTU Size). I'm able to read out the attribute value on the Entity Attribute characteristic, unfortunately I have no idea how I can do a multiple read on the same characteristic or how this should work. Do you have any idea?

Thanks

RE: Apple Media Service

run_ar — Thu, 10 Jan 2019 19:53:21 GMT

Hi,

Unfortunately we do not have any examples for AMS, but as you say it seems to be quite similar to ANCS in many ways. I did not have time to look at your code. But given that you are able to bond and discover the service. You should probably subscribe to entity updates next. guess you are already looking at this, but: first needs to subscribe for GATT notifications on the Entity Update characteristic. Then, the MR writes commands to the Entity Update characteristic to inform the MS which entity/attribute pair values it wants to know

Doesn't seem to be to many id's to choose from though.

So write e.g 02 00 01 02 03 to the Entity Update characteristic in order to subscribe to:

EntityIDTrack, TrackAttributeIDArtist,TrackAttributeIDAlbum, TrackAttributeIDTitle and TrackAttributeIDDuration

RE: Apple Media Service

thischier — Wed, 09 Jan 2019 15:10:35 GMT

I made some progress since yesterday...

I tried to create the Apple Media Service based on Nordic's ANCS example because the two services has some common parts...

I also made a copy of the ble_ancs_c example and integrated the ams instead of the ancs. Logically I called it ble_ams_c_example.

I manage to connect to my iPhone, pair with the Dev-Board and discover the AMS with all its characteristics. Unfortunately I have no idea how I can progress further, such as send controls or get the desired information on music tracks from the iPhone.

Attached is the current state of the project, probably one of the engineers @ Nordic has ideas what the next steps are...

Thanks in advance.

PS: The project is compiled for SDK15.0.0. To get it working, copy it in the ble_peripheral example folder.

devzone.nordicsemi.com/.../ble_5F00_app_5F00_ams_5F00_c.rar