Re: Positional/physical addressing

On 6/26/2025 9:53 AM, Liz Tuddenham wrote:

Don Y <blockedofcourse@foo.invalid> wrote:
 

On 6/26/2025 1:59 AM, Liz Tuddenham wrote:

This is too "high tech".  You're effectively trying to build a TDR into
each device.  Recall, I want these to be dirt cheap because I use so
many of them in a system.

>
Actually the individual devices just need to store the time between two
clear digital pulses as a number.  If the devices are never closer than
one yard apart, a 300 Mc/s clock speed will be sufficient to distinguish
between them.  (The twin identification pulses will be spaced by double
the path length.)

>
Sorry, this is a *display*.  Even as oversized as it is (a few
square feet), it is quite possible that devices will be immediately
adjacent -- a fraction of an inch apart.

 I hadn't realised they were that close together.  Obviously my
suggestion fir timing is a non-starter.

There are a *lot* of them (hundreds).  So, I have to try to
pack them as densely as possible.
The best analogy would be the "activity indicators" on
network switches; they exist so you can visually identify
ports that are active, inactive, failed, etc.  A simple
glance is usually enough to spot anomalies.
Now, add to that, being able to make this determination
with your eyes closed.