ESP-DMX DMX to Artnet, sending to a multiple interfaces

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Joined: Sat Apr 27, 2019 6:39 pm

ESP-DMX DMX to Artnet, sending to a multiple interfaces

Post by Libeo »

Hi Claude,
Thanks very much for your work and sharing your projeckts.
I built a Nodemcu with your ESP-DMX example in LXDMXWiFi_Library-master.
My purpouse was to connect the board to my DMX mixer output for converting DMX to Artnet and sending it via wifi. The board works very good when I set ESP-DMX in "station mode" and set "to net" field to "".
In this mode I am able to send artnet packets to multiple interfaces Artnet to DMX (in the same network) and control the light connected with them.

I wish I could use ESP-DMX in AP mode but in this mode I can send Artnet packets only at one interface Artnet to DMX beacouse I must set the specific IP address in "to net" field.
Is it possible to modify the firmware tor send Artnet packets to all IP range in the network in AP mode?

Thanks a lot
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Post by admin »

There are a couple of issues to consider.

First is sending Art-Net to a broadcast address. I'm not sure why, but I have not had any luck with a class A subnet mask and the corresponding broadcast address. Setting up the access point as follows works for me:

Code: Select all

WiFi.softAPConfig(IPAddress(10,110,115,10), IPAddress(10,110,115,10), IPAddress(255,255,255,0));
The broadcast address and subnet mask should send to all nodes. But, for some reason, I have to use and a subnet mask to make broadcast work. The default subnet mask for a class A address -(that is an address where the first octet is 10)- would be with a corresponding broadcast address of I don't know why the subnet mask needs to be narrower on the ESP8266. But, that's what happens for me.

The second issue is if the ESP8266 in access point mode is capable of supporting more than one connection. I was not successful connecting more than one computer to an ESP8266 in access mode while Broadcasting Art-Net dmx. Regardless of if you could get this to work, I don't think it is the best idea. The power consumption of the ESP8266 goes way up when it transmits WiFi. This tells me it is being taxed. So, for each node that connects
to the access point, the ESP8266 would need to broadcast an individual UDP Art-Net packet. The routing may be that a single packet goes to all connected addresses. But, that is different from the actual hardware part of sending it to connected devices. I think you'd have a much more reliable setup if you use even a cheap consumer WiFi route to distribute your broadcast packets. That way the transmitting ESP8266 only has to send one packet addressed to the broadcast address to the router and the hardware in the router will distribute it to listening devices from there. If you have lots of listening devices, you might need a beefier router on the same principal as why you might not want to try to connect more than one device to an ESP8266 in Access Point mode..
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