Electronic – meaning of set low/set high


I often see those phrases in tutorials with microcontroller I/O. An example use is "set pin 3 high", or "set pin 5 low for 20 ms".

I also recall reading several different definitions on what that terminology means. Does the low in "set low" mean low impedance? Does it mean low logic level (0 volts)? Or does it mean low as in negative voltage? Or is there even a universal meaning for those phrases?

Best Answer

In the root of the expression, it is "set the bit high/low (=1/0)"

It usually means set the corresponding pin "high logic level" and "low logic level", accordingly.

You would have to consult the documentation of your microcontroller, but it almost always is "set the output voltage to Vss/Vdd" (VssIO/VddIO if your micro has separate IO and core power supplies).