[OpenTRV-dev] ID length

[Damon Hart-Davis]

Hi,

I’m adding a locally-generated random ID to each node, to be used as an ID (or part of one) when there is not something more specific such as an FHT8V house code set.

In fact it’s designed so that each byte is in the range 0x80 to 0xfe so that it is not confusable with a house code (each byte in the range 0 to 99) or an unprogrammed EEPROM byte (0xff).

But, I’m wondering how big the ID should be.  An obvious size is 2 bytes to match a house code (and be longer than a JeeNode ID for example), but remembering Amdahl’s comment about running out of address bits being the really difficult thing to get round, and wanting avoid collisions even in larger establishments, I wonder if I should have (say) 4 bytes.  I don’t necessarily have to transmit/use all the ID bytes/bits in all circumstances.

Any thoughts?

Rgds

Damon