Teensy 4.1 Multicast

[g0orx]

I have been trying to get Multicast working on a Teensy 4.1. I get a failure when I try to join a group. I changed the code to set errno to the error returned from igmp_joingroup_netif so that I could print out the error which is -6 (ENXIO - No such device or address). I am using DHCP to get the address of the Teensy and then use Ethernet.broadcastIP() to get the IP address to pass as the group IP address.

Udp.beginMulticastWithReuse(Ethernet.broadcastIP(), 1024)

Some debug output showing DHCP worked OK:

Initialize Ethernet
Ethernet begin
Get DHCP address
linkstate=true
IP Address: 192.168.1.124
Broadcast Address: 192.168.1.255
Udp.beginMulticast failed: errno=-6

Any ideas why this is not working? Do I need to change some configuration in QNEthernet.

[ssilverman]

The broadcast address isn’t a multicast address.

[g0orx]

Thanks. I was being stupid. Now works OK with a valid Multicast address.

[ssilverman]

Great! I’m glad it’s working.