Posted: Thu Feb 17, 2005 12:27 pm Post subject: Open Collector?
Hello Group,
I was wondering if the AVR90S2313 has an Open Colector Output if the Pullups are not active? Is there anyone who knows if it is so?
I'd like to use the Output parallel to a switch witch pulls the line to ground.
Else I have to use something like an ULN2003 or so.
Joined: 14 Aug 2004 Posts: 1384 Location: Dallas / Fort Worth, Texas (USA)
Posted: Thu Feb 17, 2005 7:07 pm Post subject:
No, AVR's don't have open collector outputs. The internal pullups come into play (optionally) for pins set as input. Pins set as output will both source and sink current (produce 5v & ground).
You may be able to connect your switch and 2313 output with a pair of small diodes and a pullup like so.... Diode Logic . Either pulling low would produce a low (.7v which is dropped across the diode) at point Z.
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