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The Projects Forum Working on an electronics project and would like some suggestions, help or critiques? If you would like to comment or assist others with their projects, this is the place to do it.

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Old 01-28-2013, 12:10 PM
sirch2 sirch2 is offline
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Default Set Arduino pin to High Impedance (floating)

The circuit shown below is for a 40kHz ultrasonic rangefinder. I have put together a variation of the circuit using an Arduino and not including the I2C code/connector (the original code is in Assembly with which I am not too familiar so I am rewriting it).

The reciever section includes 4 Op Amps, the middle two of which are supposed to provide selectable gain. I am assuming that I need to toggle the resistsors from High Impedance to Low (ground) to change the gain and I can set the relevat pins to OUTPUT, LOW to ground them.

My question is how do I set the pins back to floating in on the Arduino? Would it be enough to set it to HIGH?

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Old 01-28-2013, 12:44 PM
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MrChips MrChips is offline
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There is a register called DDRA. Set this to 0 to set all pins of PORTA to high impedance.
Specifically, set the corresponding bit to 1 that you wish to be an output.
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