Dynomotion

Group: DynoMotion Message: 875 From: ca_gray751 Date: 1/19/2011
Subject: GP Input
I want to connect a simple mechanical switch to one of the inputs on JP12. I connected the NO side of switch to pin 5 and the COM to pin 37. Shouldn't see the state of bit 132 toggle in the Digital IO screen as I operate the switch?
Group: DynoMotion Message: 876 From: Tom Kerekes Date: 1/19/2011
Subject: Re: GP Input
Hi Allen,
 
You would need to add a pull up resistor (something like 1K ohm) connected to +5V (or 3.3V would also work).  When the switch opens the resistor will gently pull the signal up towards +5V.  When the switch closes it will force the pin low.  Without a pull up resistor when the switch opens the pin will "float" as an undriven signal and is likely to remain in it's previous state (which was low) and you will not see any change.
 
Regards,
TK