PCM programmer
Joined: 06 Sep 2003 Posts: 21708
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Posted: Mon Jul 25, 2005 12:33 am |
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The PIC doesn't have an output enable control on its pins,
in the same way that a 74HCT245 bi-directional buffer chip has.
You can't completely disconnect a PIC pin from the internal
circuits inside the PIC.
So the next best thing is to make it into an input pin,
by using the output_float() function. Or use set_tris_x().
The pin will then be in a Hi-Z state, so it won't affect whatever
external circuits are connected to the pin. However, if the
pin is left floating (ie., it's not driven and there's no pull-up
or pull-down resistor), it could float right at the CMOS
switching point which could cause massive noise to be
amplified inside the PIC with unknown effect.
So, the short answer is: Use output_float() |
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