ADC circuit help " is this possible "

[HankMcSpank]

I'm with charles...what made you choose 10k for the upper resistor?<br>
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If you fed say a fixed voltage 1.024V to the top of the resistor chain, and brought R1 down top something more appropriate like 100 Ohms. (the chain would be a draw about 10mA so would need external power)<br>
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If you then go with a PIC12lf1822...you can set its ADC poistive reference to its internal vref of 1.024V (even if it's supply is 3.3V)<br>
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if you used 10 bits, this in theory would yield 1mV resolution (can't predict how noise will start impacting here though!) ....which ought to be sufficient.<br><br>Another idea would be to have the 3 ohm device turn on/off a mosfet, which IN TURN&nbsp;then kicKs in higher value resistors in your divider chain ...which would make the whole thing a lot easier.<br><br>Without seeing more details, I'm not sure ADC is the solution ....can you ground these 3 ohm devices so they could for example&nbsp;pull a PIC IO pin down to ground - this would be a far more robust method of establishing which device is on or off....simply&nbsp;use an&nbsp;IOC interrupt.<br><br>