NRF52840: New Project - Gazelle vs Bluetooth 5

[BearedTree]

Hello,

This is my first time taking a crack at embedded wifi, and I'm currently creating multiple wireless devices to pair with a usb dongle. The Antenna prototype is being sorted in Matlab to get a tuned footprint that—hopefully—fit the enclosures to be refined down the road.

The peripherals will have some switches, potentiometers, and a few sensors. Per a colleague's recommendation, I was directed towards the Nordic product line: specifically the nrf24l01 for either ESB or Gazelle. As that line is depreciated, I started looking at the 52840 since it supports USB, Gazelle, ESB, and Bluetooth 5 out of the box.

Since I'm planning on pairing the peripherals to an accompanying USB dongle and power efficiency is high on the list, it looks like Gazelle may still be the better the better protocol to use in this scenario. Is that observation correct or is it fairly irrelevant? It appears the only benefit to Bluetooth 5 would be if I were trying to connect it to other Bluetooth compatible devices, and this was actually a no-go per the use case.

[Einar Thorsrud]

Hi,

ESB is probably not a good fit, as it is quite simple and lacks several important features. Gazelle is a posibility. It support pairing, and frequency hopping, and is in some ways similar to Bluetooth. If you are starting a new project now I would look at Bluetooth first, unless there is a paticular reason why you think Gazelle would be a better fit.

Br,

Einar

[BearedTree]

Thanks, Einar.

Ya, after I head gone through the docs, ESB did not seem like a good fit, which is why I ended up looking at Gazelle or Bluetooth.

The reason against Bluetooth, from what I understand, is that they want to limit the ability for devices to connect to just the specified peripherals and know that they are set to sync with any given-specific USB dongle. It seems like there was some concern about the dongle advertising itself and potentially getting connected to. There was also concern about the limitation of the Bluetooth pin complexity, but I have not  messed around with that protocol to know if there is a more robust way to manage/accept connections.

Gazelle's pairing seems to be a better fit given those points.

[Einar Thorsrud]

Hi,

BearedTree said:

they want to limit the ability for devices to connect to just the specified peripherals and know that they are set to sync with any given-specific USB dongle.

You can do this with Bluetooth as well, using pairing/bonding and filter accept list (whitelist). But pairing the dongle and devices in the factory may be a bit more tedious.

BearedTree said:

It seems like there was some concern about the dongle advertising itself and potentially getting connected to.

That depends on how you design the firmware on the dongle. If you want the dongle to act as a centrlal only, it does not have to matter.

BearedTree said:

There was also concern about the limitation of the Bluetooth pin complexity, but I have not  messed around with that protocol to know if there is a more robust way to manage/accept connections.

What do you mean by "pin complexity" here? But you are right that Bluetooth is a more complex protocol.

I think most of the arguments agains Bluetooth are less strong than you may think, but on the other hand this use case does fit what Gazell was designed for (a dongle without power consumption limitations, and limited peripherals). So I would choose Bluetooth if I were you, primarily because this is a seems line use case that also fits Bluetooth very well and Bluetooth is much more used.

[BearedTree]

Einar Thorsrud said:

You can do this with Bluetooth as well, using pairing/bonding and filter accept list (whitelist). But pairing the dongle and devices in the factory may be a bit more tedious.

I believe it had more to do with the end-use case regarding the ability to prevent a bunch of advertising to non-desired devices, not necessarily production related.

This is a more custom job, so this would not be going to large-scale production; the clients are also not developers, and they just did not want to see a bunch of devices on their iphones etc.

Einar Thorsrud said:

What do you mean by "pin complexity" here? But you are right that Bluetooth is a more complex protocol.

The client, I believe, was talking about the ability to add a pin/passkey to prevent unauthorized bluetooth connections. I have not really looked at the Bluetooth protocol a whole lot, so I just put what their concern was. The filter list probably solves that issue.

I'll take some time to go over the bluetooth 5 spec before proceeding. I know, at least, Gazelle fits the use case.