nRf mesh

[smarter]

hello, 

we are interesting in some of your products and please answer my questions if you can. 

we are building a big parking place with private parking lots with individual gates. this parking gates have to receive and send bluetooth signals to operate. now we want to build a bluetooth mesh network so that parking can be operated by single desktop. so my questions are -

1) can nRF52840 Dongle give and receive bluetooth signals from any desktop? 

2) can nRF52840 DK receive and send bluetooth signals from/to nRF52840 Dongle?

3) if yes, can nRF52840 DK receive bluetooth information from Dongle and than send it to final device ( in our case to individual parking gate) and recive signal from final device and send it to dongle?

4) if yes, how many parking gates can nRF52840 DK work with simultaneously. 

5) what is the range of bluetooth signals for NRF52840 (how close parking ga gates has to be to work with DK)? 

6) can we use nRF Connect for Desktop software to build mesh and operate it. 

7) can nRF52840 DK or Dongle operate using wi-fi? 

[Edvin]

Hello,

1) Yes. The dongle can communicate with any BLE device.

2) Yes. They can both communicate with BLE devices.

3) What protocol (BLE or Mesh) is your "final device" using? Either way, I assume the answer is yes.

4) Are you talking about Mesh or Bluetooth Low energy (BLE) now? If BLE, one nRF52840 can have up to 20 connections. In Mesh you can have probably as many as you like. The theoretical limit is about 32000 nodes, but the throughput lowers when the amount of nodes increase.

5) It is difficult to give an exact answer. It depends heavily on the environment (concrete vs. wooden walls vs. clear line of sight), the background noise etc. If you have a mesh network, the network range will extend through the nodes. Not all nodes has to be in range of one another, as long as there is a path of nodes within range between the endpoints that communicate.

6) Yes you can. Please check out this github repo:

https://github.com/NordicSemiconductor/pc-nrfconnect-core

7) No. The radios doesn't support WiFi. Is that what you meant, or did you mean "coexist" with WiFi on another chip?

I hope that clarifies some of your questions. Basically, if you have an nRF52840, it supports up to 20 concurrent BLE connections. It can also be a mesh node (probably not at the same time as supporting 20 connections, due to memory and time restrictions). 

I imagine you would have quite a large number of "parking gates". Maybe a couple of hundred? I suggest you look into setting these up as Bluetooth Mesh nodes, which seems like a good choice of protocol for your devices. I imagine it isn't too much data being transferred to and from the parking gates?

If you want to communicate with this network with a computer, you would need one device that can "translate" from Mesh to either BLE or Serial (UART or USB). You can do this with an nRF52840. How do you want your network data to your computer? BLE or Serial? Or do you need it through WiFi? If so, you need a node that supports WiFi and Mesh. WiFi isn't supported in any of our chips, unfortunately. But you can create a node that uses an nRF52840 to read the Mesh messages, and then send it to another device over Serial or BLE, and this device (e.g. a Raspberry Pi) can do the network part.

Best regards,

Edvin

[smarter]

Hello Edvin,

Sorry for the late response.

Yes, I have a big number of parking gates, 430. I want to make a single platform which can communicate with all of them from a server. I'm planning to use Nrf52840 devices to create a mesh system and connect each of them to multiple parking gates. Then I will connect a raspberry pi to this mesh system (pi will be connected to one Nrf52840) and it will send information to the server over Wi-fi.

I have a few questions:

1). Can I plug Nrf52840 Dongle directly into a usb charger or does it need to be connected to any other board? I mean will it work if I just power the dongles using a usb charger?

2). Which device will be a better solution for my problem: Nrf52840 DK or Nrf52840 Dongle? And why?

3). Can I connect Nrf52840 DK and Nrf52840 Dongle into a raspberry pi directly with a usb cable? Or do they need to communicate with pi over bluetooth?

4). How much is the range of Nrf52840 in an open area, with no walls or barriers? I do hope to get at least 30-50 m range.

Thanks in advance

[Edvin]

1) Yes. They only need power to operate as a mesh node. In addition it needs to be connected to the rest of the HW in your parking gate, depending on what you are using them for. I assume you have some sort of sensor or motor via SPI, UART or similar.

2) For development, I really suggest that you use the nRF52840 DK, because it is easier to debug on this device (because it has an on board debugger). When you have an application that is working, you can port it to fit the dongle instead, and then deploy the firmware to all your dongles (the gates). Besides this, it is the same chip running on both the dongles and the DK. But you should be aware of this blog post before you start programming your dongles for the first time. Also, please note that the USB part of the dongle isn't connected to the normal GPIOs. They are the USB pins, and this can't be changed/configured on the dongle. If you need GPIOs for SPI, UART, TWI/I2C, or something else, you must use the pinouts on the side of the dongle.

3) They can be connected directly or via cable. The Dongle has one USB port, which is the part that looks like the USB stick on the end of the dongle. The DK has two USB ports. The one on the short end is the USB port that goes through the programming chip. It can be used for programming, and UART communication over USB, which is translated automatically via the programming chip, as long as the UART Pins P0.06 and P0.08 are used in the UART settings. They are set to this by default in our examples.
The USB port on the long side of the DK is the USB peripheral. You can use this for direct USB communication. 

4) 50 meters is pushing it a bit. At least if you have traffic from other devices as well (430 devices). If you use a Mesh network, the range will be increased throughout the network. You would only need to be in range to the closest node, and the messages will be passed on (relayed) through the network.

Best regards,

Edvin

[awneil]

Why are we suddenly seeing so many like this ... ?

https://devzone.nordicsemi.com/f/nordic-q-a/46811/nrf52840-dongle

[Davit Tsakadze]

Can I use the dongle to just extend the range of my laptop's bluetooth? I mean, if I mesh 2 dongles with each other, then insert one dongle into my laptop, will I be able to connect to devices that are in range of the second dongle?