Looking for a mechanical switch substitute
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From:	
Fred Maher <fredfmah@yahoo.com>  [Chat now]
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To:	LTspice@yahoogroups.com	
	
 	
LTspice matrix query Dec2010.jpg (52KB)  View Image  
I have an analogue 4 x 4  switch idea that uses only one Micro Controller pin.

This 'miracle '  sends 16 unique analogue voltages to just ONE ADC input pin on the uC .

Testing the Assembly code  for the hex 1 pin keypad , all is debugged and  working fine,

But I don't seem to know enough to do an LTspice simulation.

The LTspice switch SW doesn't lend itself  as far as I can see to to being part of a matrix.

Basically for a keypad   application, switch speed is not an issue, nor is denouncing, my case controlled  by a software routine

 I'm thinking along the lines that the 16  mechanical switches are really
16 resistors which can have two states:-
Perhaps....
open = say 100Mohm
closed = say 0.001 ohm

Q1. Is there some combination of .step and a resistance change command that will enable me to output 17 different DC levels across the output resistor R37. ???

Many thanks if some kind soul has a reference to a similar question in the enormous data base of circuits
or
 has  anyone  done a similar simulation.?

Bye and thanks
Fred
