nRF5340 - IoT application

[Gabriele]

Hi,

I'm trying to devise the hardware platform for a Home Monitoring medical device.
In the first place I planned to use the NORDIC nRF5340. With its large memory it would be perfect to run the application linked to a companion Smartphone App.
Thereafter the boss came with a new request: "make it versatile enough to work also as a IoT device".
I'm not a master of this topic (not yet) but I think this translates into adding a Wi-Fi capability to the device, because most of the potential users don't have a Thread or Zigbee infrastructure at home.
Thus if I want to continue with NORDIC nRF5340 I have to add an extra module, as shown in picture.
One problem is how to handle with the coexistence problem ? Can you suggest the smallest Wi-Fi chip that fits the design ?

I'm open to advice and critics

Gabriele

[Einar Thorsrud]

Hi,

Perhaps awneil or others on this forum can suggest some WiFi chips, Nordic do not recommend any specific. Regarding WiFi coexistence and the nRF5340 I expect there will be some support for that going forward and the BLE stack matures. Currently, the QoS module is part of the nRF Connect SDK. There is currently no Packet Traffic Arbitration (PTA) interface support.

[Gabriele]

Thank you Einar for your reply.
The module WFM200S (by Silicon Labs) seems it could fill the gap (see picture).

WFM200S has PTA interface to handle coexistence.
I think I have two possibilities
- ignore PTA and turn OFF BLE/WiFi when using WiFi/BLE
- write a custom 3-wire PTA module to be integrated with the BLE Controller application running in the Network Core

Furthermore, as shown in the picture, WFM200S comes with a limited software stack. The host receives IP packets and must implement all stack layers above it. I don't know if NRF Connect SDK provides any library do this job, nor how much of the Application core memory this layer will drain.

[Einar Thorsrud]

Hi,

Gabriele said:

I think I have two possibilities
- ignore PTA and turn OFF BLE/WiFi when using WiFi/BLE
- write a custom 3-wire PTA module to be integrated with the BLE Controller application running in the Network Core

A third possibility could be to ignore WiFi coexistence and ensure that the BLE connection parameters have some slack. If you do not send long BLE packets nor with a very high frequency, then in many cases you should see an acceptable level of packet loss. This would be application specific, though. I would also expect support for PTA at some point, though I cannot say when that would happen.

The nRF Connect SDK does not have any code specific to WFM200S, so integrating that would be up to you. I would be surprised if you should see memory as a problem with the nRF5340 app core, unless you also have other memory intensive part of your application, as the nRF5340 app core has 1 MB flash and 512 kB RAM.