Hello everyone. I am working on a design where something triggers a relay which feeds a ground to me. In the schematic below, this is what's going to the IN pin. My AVR then detects that as being low (due to it being high biased by default) and does what it needs to.
Now, if I take that IN pin and send it to the ground of the AVR or the voltage regulator, the Atmel sees it as being sent low and it works just fine. However, the ground that the relay triggers, seems to carry a resistance. I can ring that ground (@ IN) and the one the AVR or VR uses, so it does conduct fine. However, if I measure it's resistance I get between 1ohm and 3ohms. Given R1 is ~10k, I would think that PB0 (on the Atmel) should still be sent low in the event I hook up the "ground."
So, here is the idea I had. Since I can use that "ground" and a 5V line to turn on something like an LED, why not use that to turn on a device(perhaps a logic gate?) that will then send the AVR's input high (the code can be changed, but the input that comes to "IN" cannot)?
Does anyone have any ideas for this?
**broken link removed**