Help PIC16C65 -MCLR

Feb 01, 2004 5 Replies
R

Aaaargh! Rush job and my brother has suddenly stopped writing firmware and is beating his head against a PIC16C65 problem



"The reset line (-MCLR) is being held partly down by the CPU so the CPU never runs".



Does anyone know why this is? Or maybe someone could point me at a PICky newsgroup where I can get an answer?



I already had to dash over there with my programmer this morning when his went t*ts up at exactly the wrong moment, besides, it would be kind of impressive if lil'ol'me sorted out something before he did.



best regards



Robin G Hewitt


Vote
Twitter Facebook LinkedIn
D

AFAIK the PIC never drives the MCLR line - it is an input ! Normal practice is to tie to VCC with a wire or resistor. I suppose if you use a large enough resistor you might have trouble with leakage (or slow rise time on power on).

Dave

Vote
Twitter Facebook LinkedIn
S

Or bro has fried that particular chip.

Best regards, Spehro Pefhany

Vote
Twitter Facebook LinkedIn
R

Hi Spehro Pefhany

Good point, he tried them both but I just ordered a spare :o)

best regards

Robin G Hewitt

Vote
Twitter Facebook LinkedIn
D

If bro has MCLR connected to VCC, and tries to program it, he will apply VPP (12 v ?) to the vcc terminal and anything connected to it - which may be bad news for the device and/or the programmer ...

Dave

Vote
Twitter Facebook LinkedIn
R

Hi Dave

He's programming with an EMP 11 programmer, the PIC is out of the board and it verifies okay. The reset circuit is a resistor, a diode, a capacitor and a switch, looks good to me. I'm sure he'll figure it out, I was just trying to save some time.

best regards

Robin G Hewitt

Vote
Twitter Facebook LinkedIn

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required