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Gday Roger
You wont short anything out.
Normally, there will be a 10 to 100k resistor between the 5V rail and the port. ie
+5V -- 100k resistor -- CPU Port -- AssertPin -- switch --- Ground
When the switch is open, ie the Assert pin is floating, the pullup makes the voltage at CPU Port = +5
When the AssertPin is connected to ground, the CPU Port gets pulled to ground, so there is no way to actually short anything via the ST4 port.
Andrew
Last edited by AndrewJ; 19-03-2017 at 07:47 PM.
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