Kirk Humphries

CONNECTED VDD1 AND VDD2 TO 5V - OPPS - NO PIERCE OSC

Discussion created by Kirk Humphries Employee on Jan 27, 2006

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Posted: Wed Dec 7, 2005  3:39 am



THANKS TO AN OLD ____ POSTING - I FOUND I HAD CONNECTED VDD1 AND VDD2 DIRECTLY TO VDD. THIS IS ON A MC9S12E128. THE WIERD SYMPTOM IS WE COULDN'T GET THE PIERCE TO WORK - EVERYTHING ELSE  SEEMED TO WORK. WE JUST DISCOVERED THIS TONIGHT SO WE WILL TEST IT TOMORROW.

 

BUT WE HAVE A BIG SAMPLE OF THESE IN THE FIELD FOR ANYONE WHO CARES ABOUT WHAT HAPPENS.

 

50 UNITS IN THE FIELD FOR ONE YEAR. 10 - 20% FAIL AFTER 1-2 MONTHS. SOME DEAD SOME CAN READ AND WRITE FLASH BUT WOULDNT RUN.

 

TOMORROW WE WILL TRY AND RESSUCITATE SOME DEAD ONES FOR FUN. BUT I WOULDN'T TRUST ANY THAT WERE RUN THAT WAY.

 

THANKS AGAIN ____ FOR THE OLD POSTING.

 

ANYONE ELSE THAT HAS DONE THE SAME THING PLEASE TELL ME WHAT HAPPENED TO YOUR UNITS.

 


 

Posted: Wed Dec 7, 2005  4:00 am

 

Unless you mean to be yelling at all the ppl here that might help you for free, you shouldn't type in all caps.

 

Regards,

 


 

Posted: Wed Dec 7, 2005  10:03 am

 

No I wasn't yelling. I am sincerely thanking everyone here for helping me here. If it weren't for the failures and all the help and info I've gotten from this forum I don't know if we would have ever found this error. I am sincerely thankful for everyone who helps in this forum Typing in Caps was just my style. Now what was a nightmare product will turn immediately into a very robust product.

 

This very real problem was masked by the fact that not much seemed to be wrong, except the Pierce oscillator issue. It would have been nice if Mot had named these two pins Vint1 and Vint2, then most people that make this mistake the first time would not have made the mistake.

 


 

Posted: Wed Dec 7, 2005  10:12 am

 

Note that also VDDPLL is an internal power-supply, and is 2.5V. It should too not be connected to your 5V.

 


 

Posted: Wed Dec 7, 2005  2:51 pm

 

Thanks, I got that one correct.

 


 

Posted: Thu Dec 8, 2005  12:38 pm

 

Problem solved - our test on the Pierce worked perfectly. Thanks Doron.

 

I posted another pcb question today - see 4 layer vs 2 layer post.

 


 

Posted: Fri Dec 9, 2005  3:54 am

 

Would you please post your solution. What did you do with VDD1 and VDD2 that you did not do before, it will save us looking through the old posts.

 


 

Posted: Fri Dec 9, 2005  4:44 am

 

I disconnected VDD1 and VDD2 from the 5V supply and connected them only to the bypass capacitors as specified in the user guide. Now the Pierce osc works perfectly.

Message Edited by khumphri on 01-27-2006 07:12 AM

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