Using nRF52-DK, Is there an example of a Star topology?

RE: Using nRF52-DK, Is there an example of a Star topology?

endnode — Sat, 04 Nov 2017 08:18:10 GMT

Sure, you have countless options. There are some combo chips like popular ESP32 or Broadcom BCM43012, then you have many modules with combo or dual chips and then you have many "boxes" with wireless things starting from all these RPi and BananaPi and UDROID and whatever up to all Windows/Linux laptops and desktops. So whatever is your budget, power restrictions, programming skills, space restrictions you should find the right thing for you.

RE: Using nRF52-DK, Is there an example of a Star topology?

asha — Fri, 03 Nov 2017 18:02:24 GMT

Hi, Thank you for answering.

I am wondering if there is another device that can support BLE stack as well as the WIFI. I mean suppose we have multiple nRF52DK with BLE Stack that can connect with this hub that has BLE and WIFI and does not have to be nRF52DK. Can this hub be a Windows 8 or 10 PC or a Raspberry PI? I realize that an application will need to be developed for the Windows 8 or 10 PC or a Raspberry PI running Linux.

Thanks, Asha

RE: Using nRF52-DK, Is there an example of a Star topology?

endnode — Fri, 03 Nov 2017 00:44:48 GMT

There is no single example solving your problem I'm afraid. Some aspects are coming to the bottlenecks of whole embedded system (like how to operate concurrent links on single low-power radio with single-threaded low-power processor with stack which cannot consume more than ¬100kB of flash and few kB of RAM) so while for some things you will find examples which you can just copy&paste and recompile for some things you will need to learn how API looks like, study examples how it is used (yes, that multilink GAP Central FW project is the great start) and you will need to apply them carefully to that IoT project.

RE: Using nRF52-DK, Is there an example of a Star topology?

asha — Fri, 03 Nov 2017 00:03:36 GMT

Hi,

I understand about the complexity and that is why I had asked if there is an example code?? If not, I can understand. Thanks, Asha

RE: Using nRF52-DK, Is there an example of a Star topology?

endnode — Thu, 02 Nov 2017 23:57:29 GMT

Oh there are lot of things to change and add! If I understand the code correctly it only solves "upstream" part so you need to find how BLE stack is initialized, add more roles/slots to handle more connections in parallel, initialize GAP and GATT layers to handle them, separate events between "IoT" and your "app" part, manage scanning and connecting and GATT Service discovery (assuming nRF5 DK acts as GAP Peripheral towards RPi but as GAP Central + GATT Client towards "sensors") and all the app layer protocols on top of it (e.g. HRM if you really care about this one).

RE: Using nRF52-DK, Is there an example of a Star topology?

asha — Thu, 02 Nov 2017 23:42:35 GMT

Hi,

Thank you for finally understanding my question.

So you are confirming that the \examples\iot\udp\ipv6\client example will work with connecting BLE devices but I have to add the code to "scan" for devices and then "connect" ??

Correct? Thanks, Asha

RE: Using nRF52-DK, Is there an example of a Star topology?

endnode — Thu, 02 Nov 2017 23:34:03 GMT

(however kind warning: understanding of TCP/IP and COAP and other higher-level networking stuff won't help you at all, this is imply about BLE stack and API to its GATT and GAP layers, so potentially lot of new things and space for frustration...)

RE: Using nRF52-DK, Is there an example of a Star topology?

endnode — Thu, 02 Nov 2017 23:31:44 GMT

Okey, so now I understand your question as "How to modify \examples\iot\udp\ipv6\client example from Nordic that it will connect to certain BLE devices (e.g. HRM), collect data/manage them and on the other side communicate with the cloud over IPv6 (which is working for me as such right now?" And I believe the answer is "Well this is just and example from Nordic and you need to write all application level by yourself. And yes, collecting some data or doing whatever else over BLE is application from IoT gateway point of view. Luckily there are tons of examples in nRF5 SDK so mearging/inspiring should be a big problem."

Is my understanding correct now?

RE: Using nRF52-DK, Is there an example of a Star topology?

asha — Thu, 02 Nov 2017 23:26:37 GMT

Hi, My objective is that not all BLE devices (blue tooth low energy devices such as a heart rate monitor or temperature ) connect to the Cloud. I want a BLE device that just acts as a gateway to the cloud. I am connecting to the cloud via a Raspberry PI.

I have run the "nRF5_SDK_14.1.0_1dda907\examples\iot\udp\ipv6\client" example on one nRF52DK and was able to connect to the Raspberry PI and that connected to our company Cloud. So now I was trying to connect another nRF52DK to this "nRF5_SDK_14.1.0_1dda907\examples\iot\udp\ipv6\client".

Thanks, Asha

RE: Using nRF52-DK, Is there an example of a Star topology?

endnode — Thu, 02 Nov 2017 23:14:48 GMT

To be precise I have no clue why you mix all that IoT and UDP and COAP into the game;) What is the purpose of the nRF52 DK in your demo/app? Should it connect over BLE directly with RPI (don't know if that supports BT LE out of the box) or should it only bridge some gap over BLE to another nRFx board and that is attached to RPi over some wires? In every case you can build your BLE app to bridge 5-50 meters and transport whatever data you need and then o higher layer get these data and upload/download them from /to "cloud" through some app running in your Linux box (let it be RPi) over whatever sexy protocol. This is how most of the "IoT" use cases can be solved easily (and actually should be solved from my point of view but I'm probably too old fashion).

RE: Using nRF52-DK, Is there an example of a Star topology?

endnode — Thu, 02 Nov 2017 23:10:14 GMT

What are the links between nRF52 DK and other components? I mean what is BLE, what is UART/SPI/whatever else over wire, what part you have sorted out (in terms of FW/SW that you are fine with what it does towards "cloud" side)? I suppose there are some demos by Nordic which might fulfill most of your needs (and I believe their support will let you tomorrow when they wake up in Europe) but I'm pretty sure that these three SDK examples you mention (examples\iot\udp\ipv6\client, examples\ble_peripheral\ble_app_hrs and examples\ble_central\ble_app_multilink_central) are not meant to work together out of the box or to be more specific these two ble yes, they at least implement certain common interface (BLE GAP and GATT layers in roles which are able to work together) but one is implementing some standard BT SIG GATT profile (Heart Rate Monitor) and second demonstration LEDs manager.

RE: Using nRF52-DK, Is there an example of a Star topology?

asha — Thu, 02 Nov 2017 22:44:07 GMT

Hi, Thank you for responding. But I don't think I made myself clear.

I would like 2 BLE devices (such as nRF52-DK running an example like "nRF5_SDK_14.1.0_1dda907\examples\ble_peripheral\ble_app_hrs") sending data to the cloud via a nRF52-DK router that is running as an example "nRF5_SDK_14.1.0_1dda907\examples\iot\udp\ipv6\client".

So on one side a nRF52-DK is connecting via BLE with 2 BLE devices and on the other side thsame nRF52-DK is connecting to the cloud via the Raspberry PI.

Is this possible with Nordic nRF52-DK ??

I looked at the examples\ble_central\ble_app_multilink_central and I am wondering if I could use an example from it to connect to the Raspberry PI??

Thanks, Asha

RE: Using nRF52-DK, Is there an example of a Star topology?

endnode — Thu, 02 Nov 2017 22:21:03 GMT

Sorry but you are mixing layers in the way that there is no really good answer. By "Peripheral" you mean GAP Peripheral role as defined in BLE since v4.0? How that corresponds with IoT UDP client (which has nothing to do with BLE spec as there is nothing like this so I assume you run it somewhere on APP layer - and probably with several more SW layers in between)?

If you stay BLE world for a while then indeed star topology is basic use case of GAP Central device in the middle and whatever number (in older stacks typically up to 8, with today best stacks you should be able to operate 20 and more connections in parallel) of GAP Peripheral devices around it, there is examples\ble_central\ble_app_multilink_central example in nRF5 SDK an more.