esp-now and number of nodes [WIFI-2126]

[sajjadakhter]

i am building application that will have one master and many salves those will need to synchronize with master after every few min.
I read esp-now has 20 peer node max limit, two questions i have

1. Do i have to add node to my peer list to send message? can i just send message without adding to peer list. Can i reieve message from node that's not in my peer list?
2. Can i add node to my peer while i need to communicate and remove after wards so that i can communicate with other nodes. Then i readd once i am expecting to talk to node again.

In my this application i can drive most of the communication initiated by master except the case when salve mode when starting up.

Thanks,
Sajjad

[ESP_Alvin]

Moderator's note: edit the topic title for issue tracking, thanks.

[zhangyanjiao]

hi sajjadakhter,

1. Do i have to add node to my peer list to send message? can i just send message without adding to peer list. Can i reieve message from node that's not in my peer list?

Yes, you have to add node to the peer list, otherwise, `esp_now_send()` will return error, but you can receive message from node that's not in peer list.

2. Can i add node to my peer while i need to communicate and remove after wards so that i can communicate with other nodes. Then i readd once i am expecting to talk to node again

Yes, you can add peer with `esp_now_add_peer()` and delete it with `esp_now_del_peer`.

[sajjadakhter]

Then why there is limit of number of nodes, is it to help with broadcast to all nodes? I don't understand why there is limit of peers especially if I don't need it to receive message.

[zhangyanjiao]

We set the number of nodes because of resource constraints, especially for the encrypted node, we need to save the key.

[sajjadakhter]

why not allow a Send with key as parameter instead of managing peer list. This way user of the API can decide how to manage peers. In my case i could use NVS to store all the peer info as it only need to send messages occasionally.

[zhangyanjiao]

I'm sorry, I don't think there is any conflict between managing the peer list and your application.

[sajjadakhter]

Well it would be much cleaner interface, where can i find sources for esp-now and how can i modify it?. In my case i have quite a few peers but those are configured and saved to nvs/flash. So there is no point of keeping such list dynamic /in memory.

[zhangyanjiao]

Currently you can't mofify it