Series resistor when using weak pull-up
Hi, I am designing a board that is connected to a momentary switch,
normally i just use a pull-up resister and a series resistor and a capacitor,
the series resistor and capacitor work as a low-pass filter to suppres noise.
See the attached drawing.
But now I want to use the weak pull-up, so I just removed R1 and programmed RA4 to have weak-pull-up but it don't work if I still use R2!
Should I remove R2 or just use a smaller resistor.
Sharky
Last edited by Sharky; - 18th October 2006 at 17:03.
*Let's do it*
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Hi Sharky,
Weak pull ups work on PORTB.
Also, for some reason forum servers have some issues with attachements now.
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"If the Earth were a single state, Istanbul would be its capital." Napoleon Bonaparte
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Hmm, really on the 16F630 I use it work on PORTA.Originally Posted by sayzer
I am not having problems programming the weak pull ups.
I just want to know if I should use a serie resistor and a decoupling capacitor
as I do when I use an externally pull up resistor.
Because if I use a 10K serie resistor as I use to do, it does not work!
Yes, I can see that it is impossible to view my attachment, but I don't know why?
Sharky
*Let's do it*
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For PIC16F630, PORTA weak pull-ups OK!
No schematic, bad guess.
Forum has some issue.
Let see your schematic if you can upload it to http://picsplace.to and then put the link here.
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"If the Earth were a single state, Istanbul would be its capital." Napoleon Bonaparte
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Here is the link:
http://img4.picsplace.to/img.php?file=img4/26/weakP.JPG
Sharky
*Let's do it*
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1. 10K is too high. <1K could do... usually not needed.
2. the capacitor is usually useless as you can do the debounce in software in most case.
Steve
It's not a bug, it's a random feature.
There's no problem, only learning opportunities.
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