[Host bug/limitation] OSX does not list devices with more than 18 characters in device name?

[LeeNX]

Seem to have discovered or tracked down by accident, that OSX seems to have a limitation of 18 characters in the device name, at least one of my running Mac with macOS version 15.3 (24D60).

I really did think I was going nuts, but testing one of the example sketches - CharacteristicsConfiguration.ino, using the device name Custom Contoller Name, would not show up in my device list on the OSX machine, but was listed in LightBlue on my Android device.

Testing by changing and uploading a small difference in the sketch, turning bluetooth on the device off for 30sec and then on and waiting for 30sec to see if the device would get listed. Also validating I could see the device in LightBlue on my Android device.

I ended up at 18 characters - Custom-Contoller-N as can be seen in the screenshot.

I will try and add a note in the TroubleshootingGuide and push a PR.

[lemmingDev]

Good find!

[LeeNX]

This is actually a limitation of the Bluetooth Advertising packet size of 31 bytes - Bluetooth Advertising Packet

Less 3 bytes are occupied by the mandatory advertisement flags data., and then less bytes per advertising feature, like Advertised TX Power and/or Manufacturing data and so on.

The display name is for initial discovery and pairing, then most hosts use the characteristics Appearance with UUID 0x2a01, I think.