If this is anything other than a random happening then I'm in deep sh*t, because my top ten best selling designs all use weak pull-up's. Never, ever had a single return that has a fault on a pull-up input - and that's after years of sales...
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If this is anything other than a random happening then I'm in deep sh*t, because my top ten best selling designs all use weak pull-up's. Never, ever had a single return that has a fault on a pull-up input - and that's after years of sales...
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mmm, i don't know but you really have a PIC with a faulty internal pull-up?
If you add a external pull-up it works?
Is there any chance somewhere in your code some pin change from input to output? in this case it could disable some internal pull-up but...
Maybe some electrostatic discharge burned it? but if so... i guess it should go deeper than only the internal weak pull-up no? Strange...
Steve
It's not a bug, it's a random feature.
There's no problem, only learning opportunities.
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Yes, I think that last part should be it. I have an ICSP arrangement, with +5 to the target being supplied exclusively from an external supply. At times, when I'm not working on the project, this supply is switched off. And the programmer (an Epic clone), still connected to the PC, keeps the Vcc (not an issue in this case) *and* Vpp high, unless the programmer s/w (WinPic800) is initialised (loaded). The Pic therefore is exposed to Vpp without getting Vcc.Originally Posted by mister_e
I think this kind of abuse might have caused the damage.
And yes, I confirm that external pullups work.
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Do you have a 0.1uF capacitor across the supply lines as near to the PIC. I found that without this I would sometimes have strange issues with the way a PIC would behave. Maybe this has some bearing on the problem here ?
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