[TriEmbed] Chain-able EEPROM or Similar

[Pete Soper]

OK, my idea was idiotic because every diode enabling backward 
communication would create a fraction of a volt drop, so after a certain 
number of LED strings you wouldn't have a valid logic signal. Duh.

But a string of diodes (and one current limit resistor) between 
controller and ground would make an easy location finder if each node 
could just report the voltage it sees relative to ground. If you're 
running two extra wires around with the LED strips, why not three?

Something cheap and capable of having both memory and smarts (like an 
ATtiny) could be a I2C slave and running at low speed solves the range 
problem. Arranging for them to have unique addresses would be a pain in 
the butt with just seven bits of "address space". Dip switches or 
jumpers needed. But a binary search across a seven bit space would not 
take long to enumerate all the nodes.

1-wire is described in detail here 
<https://en.wikipedia.org/wiki/1-Wire#Communication_protocol> on 
Wikipedia. Each device has a unique 32 bit address + 8 bit "type" + 8 
bit CRC. A clever binary search scheme allows determining the IDs of a 
set on a given bus pretty quickly for a small number of them. It doesn't 
look like physical location is possible to figure out. Making an MCU 
pretend to be a 1-wire slave is hard.

But

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