Issue with Mesh Reconnection

Question

Hello Nordic Engineer, 
 
 I successfully controlled the 52840 DK through Mesh using my phone. However, after exiting the app and reopening it, I can no longer control the DK. It seems that the connection with the DK is not established. How can I reconnect to the DK? 
 The video from 0:40 to 1:18 is the waiting time and can be skipped. In the end, a timeout issue occurs. 
 Another shorter video makes me feel that devices already added to the Mesh cannot be discovered and displayed on the app page again. However, this is a secondary issue. What I want to solve now is: if either the phone or the DK disconnects, how can I reconnect them? 
 Thanks

Elfving · Accepted Answer

tony55723 said: It should be working now. In Mesh, only the proxy node can connect to the phone. After opening nRF Mesh, there’s a ‘proxy’ option in the tab bar at the bottom. I can choose whether to enable automatic connection. Once I agree, the next time I open the app, it will automatically connect for me. 
 
 Correct. Proxy is refering to GATT proxy, meaning that it has the part of the BLE stack making it capable of being connected to. Most BLE Mesh nodes don't need this, and your phone isn't a part of the Mesh network, but by conecting to a (any) proxy node you gain access to the network - much like an access point to the internet. 
 tony55723 said: In Mesh, who decides whether a device (e.g., the 52840 DK) becomes a proxy node or a relay node or other node? Is it the phone app, or is it determined during the device’s program download, where the code can set which type of node the device will become in the future? 
 You configure it. 
 tony55723 said: In this diagram, there are two proxy nodes. Is it possible for the phone to connect to both proxy nodes simultaneously? (Additional context: My intended design is like the diagram, where the phone only connects to one proxy, and then this proxy spreads the data. Also, I’m the app developer, so theoretically, I should be able to control the connection count to be 1.) 
 Hmm.. I am not sure if I see the use-case, but that shouldn't really matter. This is only limited by memory and the maximum connections BLE-wise. So yeah, that should be possible. 
 tony55723 said: The video previously showed a phone establishing a Mesh with the 52840 DK, and the build configuration was ‘nrf21540dk/nrf52840’. It seems like there’s no issue, but shouldn’t I have selected ‘nrf52840dk/nrf52840’ instead? 
 So this board naming-scheme can be a bit confusing. The first word is referring to the name of the board, which could be "nrf52840dk", or "myboardisthebestboard", it doesn't really matter naming-wise. The second word however, is the name of the SoC that is being programmed, and is then a bit limited in regards to what it can be. nrf21540dk/nrf52840 (or nrf21540dk_nrf52840 for NCS versions that do not use Hardware model 2 ) is then referring to the nRF52840 SoC on the board called nrf21540dk , which is our front-end module board. I assume the guy who selected this had this board. If not, it might happen to work, but he should build for the board he has. 
 tony55723 said: 】Continuing from question 3, I have two 52840 dongles on hand. So, for the build in VS Code, I should select ‘nrf52840dongle/nrf52840’, right? 
 Correct. 
 tony55723 said: I have two 52840 dongles, and I plan to use one of them to implement the Mesh from the previous video with the 52840 DK, but I failed. 
 The first screenshot shows that I used to develop with Keil. When I downloaded the BLE Peripheral UART example to the dongle, the phone was able to find the device through the app. 
 The second screenshot shows that I erased the program on the dongle and this time used VS Code to download it (I did the same for the 52840 DK previously). The example is the same, but this time the phone can’t find the dongle device. Why is that? 
 I believe this issue could be related a previous case I got regarding dongles. Please see my response there. 
 Regards, 
 Elfving

Issue with Mesh Reconnection

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