Running out of nodeId's

[NielBierman]

I would like to hear some opinions on the following problem.
I have a large number of nodes on the Mysensors network. I actually reached the max of 254 nodes. What would need to happen to increase the max number of nodes on the network? Will it even be possible?

Regards
Niel

[skywatch]

@NielBierman Simply add another RF gateway on a different frequency.

[TheoL]

You can change the channel, at least on the nrf24l01. Works for me. My test network has a different channel

[mfalkvidd]

That’s impressive @NielBierman, great work! Would you mind sharing what nodes you have, as inspiration for us who haven’t leveled up as far yet?

[TheoL]

I'm curious as well @NielBierman on the stuff you control and monitor over your network

[OldSurferDude]

I, too, am duly impressed that you have so many nodes! Please share more.

I run a "test" and "production" gateways, too. I have a compiler directive in the sensor software that allows me to easily switch from test to production.

At one time I was running about 10 Nano nodes and it appeared to me that they were colliding with one another, symptom being slow response times As I remember, that occurred mostly on power up after power loss. Often I'd get two nodes with the same ID. I have since put my ID in NVRAM and that helped.

So I am very interested seeing what you have done.

--OSD

[TheoL]

@OldSurferDude I always put some delays in my presentation part. That way my nodes don't perform a ddos on the gateway after powering up. But yeah curious how that goes what 254 nodes xd

[OldSurferDude]

@TheoL Not only did I put in delays, too, but I put in delays that were based upon the ID (which was stored in NVRAM)! This helped.

caveat: This is probably not accurate be helps to explain the challenges with a large network.

My initial experience with Arduino/nRF24 was using the libraries from TMRh20. Those libraries allowed a node to be a repeater, but only for 6 nodes. The primary node 0, master, only allowed 6 nodes to connect to it. The nodes connected to it also allowed 6 nodes. Subsequent nodes had to go through one of these repeating nodes. But the depth was only 4 deep. The master assigned node IDs if the node didn't already have one; similar to a MAC address.

The master also kept track of the addresses (ARP table?). Addresses were 4 octets (base 8) in the form of D/C/B/A. A node connected directly to the master had an address of 0/0/0/a (where 0/0/0/0 was reserved for the master). A node connected through another node had an address of 0/0/b/a, and so forth.

But what happens is that a parent node has to mange the data from all its child nodes and their child nodes and their child nodes. Thus a node would get so bogged down dealing with this traffic that it din't do its sensor task very well.

It is my belief that MySensors either uses TMRh20's libraries or has developed some aspects based on his initial work. I see that that TMRh20 has a version 2 and I have not experimented with it. I did find that MySensors worked better than version 1.

Thus, my curiosity.

I am also duly impressed at the magnitude of hardware. Currently a nano like device from Aliexperss is US$2-3, nRF24 ~ US$1, power supply ~ US$1.50, power cord ?, case?, sensors!? While the hardware cost is daunting, even with a PCB it's a lot of work building those up. So, yeah, I'm impressed!

-OSD

[GLAB]

@TheoL For 'non-experts', could you kindly describe how to settle a new frequency in anArduino sketch ? And maybe give an example of such a sketch ? Thanks in advance

[nagelc]

@GLAB You can set the frequencies using the settings in MyConfig.h, which is in the MySensors folder. If you put any of the defines from MyConfig.h into your sketch, they will override the MyConfig.h setting for that sketch only.
If you are using the RF24 radio, there are different channels which correspond to a given frequency. The default is channel 76. There is a list of typical channels in MyConfig.h. If you want to change the channel for all the sketches, change it in MyConfig.h. If you want to change it just for the sketch, add a define to the sketch. For example:

#define MY_RF24_CHANNEL (84)

The problem with changing the channel in a sketch is that the gateway has to be on the same channel to receive from the node. So, normally it makes sense to change in MyConfig.h because you usually want the gateway and all the nodes on the same channel.

Other radio's like the RFM69 list the frequency instead of using a channel. They can be overridden in the sketch as well. You can find the defines that are needed in MyConfig.h