That would be 30cm for the rest of the world. :)
What I'm looking for is a way to configure small modules with an address after they are installed, not using wires. The installer (person) would be at the location of the module, and will have the address to enter into the module. The need is to get the address into the module. The total data to be embedded is just a few bytes, certainly no more than 10. There may be a great many of these modules in an installation.
I was thinking of an IR solution where both module and installer tool have TX and RX to perform the configuration and verify it. Essentially the installer would point a configuration gun at the module, press the trigger, and a green LED on the gun would signify that the configuration succeeded. The module UART is already being used so this would have to be bit-banged, but since the module won't be doing anything else before configuration, that doesn't present any problems.
So, any comments on this approach, or suggestions of other approaches?