shorting pins between teensies

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kteepa

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I'm reading a proximity sensor on a Teensy 3.2 and having that Teensy 3.2 output a scaled value through its analog output to an analog input on a Teensy 4.1. I have both teensies plugged into the same laptop, and I have connected GND on T3.2 to GND on T4.1.

1) Do I need to put some sort of resistor between the analog output pin of T32 and the analog input pin of T41? I guess I'm just wondering if what I'm basically doing is shorting the pins if analogWrite goes to a max value and going to end up with fried pins on both boards if I don't have some sort of resistor between them. If so, what resistor should I use?

2) would it be better to connect AGND (instead of GND) on Teensy 3.2 to GND on Teensy 4.1?

Thanks
 
Analog inputs have extremely high impedance and draw negligible current, so a resistor is not needed.

However if there is ever a chance that one of the two processors is not powered up, or not properly initialized, then you do need some sort of protection on inputs. A 10K series resistor usually suffices.
 
jremington said:
Analog inputs have extremely high impedance and draw negligible current, so a resistor is not needed.

However if there is ever a chance that one of the two processors is not powered up, or not properly initialized, then you do need some sort of protection on inputs. A 10K series resistor usually suffices.
Click to expand...

Do you think you could clarify what you mean by not properly initialized? Could you provide an example please?
 
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