ANT Forum

Hi everybody!

I will soon get my ANT+ dev kit to play around a bit and test my ideas, but I have a few questions I would like to be answered before I continue my research. I've checked the dev pages and could not find it so far (still studying it)...

The scenario is the following: a network of 10 ANT+ HR devices automatically connecting to a single display (may not be an actual ANT+ display, but an ANT+ "sink" kind of device) IF the "sink" is at reach. IF the sink is not at reach, then the user should manually pair it with their smarpthone. This sink device will actually be an Android device with a specific app... Can I re-configure the sink device with the Android's app to automatically connect and get data from a list of any other commercially available ANT+ HR profile device?

Can you give me some more technical details for this architecture?

Thank you very much in advance.

Cheers!      

Hi PedroDiogo,

The 10 HR devices will automatically transmit as ANT+ masters according the the ANT+ Heart Rate Monitor Device Profile (which I assume you have read).

I am not sure if you require all 10 to be received from at the same time? If 8 or less is ok then you can use 1 channel per heart rate strap and connect to them all 'normally'.

If you need to connect to all 10 at once the central sink device would either need two ANT radios (this can be done with a phone by adding an extra ANT USB dongle) or will need to use a scan to monitor the devices. Continuous scan is not available in the ANT+ Android SDK so this would mean using a background scan.

If you expect the heart rate straps to be moving in and out of range of your device then you can use a background scan to detect them, and then open a synchronous channel with any devices that come into range.

You'll find the android section of this forum will be answered more quickly for android specific questions.

Hope that helps,

Kat      

Thanks a lot for the reply!

I understand what you say. It does seem to limit a bit my network topology needs... I saw that ANT+ supports mesh, that was why I was not that worried about the 8+ node limitation (same as BLE), but I later found out we have to implement it ourselves, which is even more complex to employ in my scenario. However, when you say "add an extra ANT+ USB dongle", are you assuming I will be using an android phone/tablet with built-in ANT+ support?

It is a shame there is no iOS support... I didn't want to limit this to one OS, although I do have Wahoo's devices and APIs.

The nodes won't be in and out of range. They will either be out (no need for background scan), or inside the closed space (manual scanning order). However, once they got out, I want them to be able to pair with existing smartphones. For interoperability sakes, I will consider going with ANT+ and BLE dual chips (N5)

I will keep investigating some more about my solution, but in the meantime, could you also tell me how can I have 50 sensors to one display? I found it here: http://www.thisisant.com/developer/ant-plus/ant-ble-comparison/#383_tab I thought the maximum per channel was 8 devices...

Thank you again!

EDIT: I found this product which does the same thing with up to 20 HR devices: http://seego.realtracksystems.com/ .
If i want my solution to work, I would have to do some sort of multiplexing like each node's master channel connected to 3 slaves and reporting back, via its single slave channel, the data from those 3 to the sink master. This is assuming I'm going with the Android device with no extra ANT+ transceiver.      

Hi again!

I'm a little confused by your use case - the initial post says that you want the central device to be Android, so I tailored my answer to that and assumed you were looking at an ANT+ phone or tablet. Where are you planning to use the N5 module?

We recommend Wahoos API for iOS, and in addition provide ANT libraries for MacOSX. The information on this page will probably be helpful for you: http://www.thisisant.com/developer/ant/starting-your-project/#73_tab

50 sensors to one display is possible by having 50 sensors transmitting and the display running either a continuous or background scan to receive the data from these sensors. The complexity of a mesh network is not required to make this work. The N5 module supports continuous scanning and background scanning. http://www.thisisant.com/developer/ant/advanced-features/#44_tab

Also, it sounds like you may have a misunderstanding of ANT channels. The term 'channel' in ANT is used differently than in bluetooth. An ANT device can typically have 8 channels (each able to be configured as a master or a slave). Master channels are used to broadcast information. Slave channels are used to listen to information from other masters (and optionally reply back). Alternatively, one of the 8 channels can be configured as a background scan to listen to many ANT masters. Or the whole radio can be used together to listen via a continuous scan (and optionally reply back). If this sounds unfamiliar to you, then I'd suggest taking some time to go through the ANT basics section: http://www.thisisant.com/developer/ant/ant-basics/

Hopefully that helps!

Kat

     

Hi Kat!

I've been doing some research and I think I now understand the basics of ANT+ connectivity. It is indeed a bit different when compared to BLE. I was checking background scanning before I read your message, and it sure is great for my needs.
The N5 will be the used for the Heart Rate sensor strap. I would like to have a maximum of 30 master nodes to only one Android tablet working in background scanning mode.

The BLE connectivity present in the HR strap is also required, because the strap itself wont be exclusively used in this closed and controlled ANT+ environment. The person wearing it will connect it to his/her smartphone via BLE to monitor the sensor data throughout the day. In other words, my solution is composed of two different environments:
1 - Collective (30 master sensing devices, max) monitoring of HR data via one single Android sink slave in background scanning mode. This is a fixed and closed place, like hospital room.
2 - One-to-one connectivity via BLE when the HR sensing device is out of the ANT+ environment.

However, I do not want the ANT+ sink device to be exclusive to Android only, so I will take another closer look at Wahoo's API and devices to see if they support background scanning with iOS.

I think I'm getting closer to my actual needs.

Thank you for everything and I must apologize for asking questions before taking a good look at ANT+'s documentation.      

Hi Pedro!

Great that things are making more sense . And now I understand your use case also!

30 x 4Hz ANT devices should coexist fine with each other, although you may want to be careful about avoiding excessive wifi interference.

I checked with a colleague and the ANT+ plugins are designed to cover the simple case of connecting to one heart rate strap at a time. You will need to use the Android ANT SDK to in order use background scanning, and you'll need to contact Shane G on this forum (http://www.thisisant.com/forum/viewforum/30/) to be able to use the ANT+ key with that SDK. The heart rate device profile is pretty simple, so you shouldn't have any issues putting that together. I'm not sure whether Wahoo's API has the background scanning feature available, so it's best to check with them directly as you say.

For the heart rate to phone individual case, it's very easy to use the ANT+ plugins to create a working app - so you might want to consider that for your Android users. Of course with the dual mode chip in the heart rate straps, your plan of also using BLE works.

You're welcome to ask questions. Of course it helps to check the documentation first (we definitely encourage that), but sometimes it isn't easy to recognize a misconception yourself.

Best regards,

Kat