Lpc2000

----- Original Message ----- 
From: "topandurangs" <pandurang@...>
To: <lpc2000@yahoogroups.com>
Sent: Wednesday, March 22, 2006 12:59 PM
Subject: [lpc2000] Re: RTC problem in 2136


> --- In lpc2000@yahoogroups.com, "Leon Heller" <leon.heller@...>
> wrote:
>>
>> ----- Original Message ----- 
>> From: "Pandurang Shinde" <pandurang@...>
>> To: <lpc2000@yahoogroups.com>
>> Sent: Wednesday, March 22, 2006 11:35 AM
>> Subject: RE: [lpc2000] Re: RTC problem in 2136
>>
>>
>> > thanks for immediate reply.
>> > Yes i am using external watch crystal of 32 khz. I have also
> found that i
>> > am not getting oscillation on that board(the board in which i am
> not
>> > getting RTC updaed value ). But when i used same crystal on
> other board
>> > it( crystal ) seems working,so crystal is fine.
>> > What are the possible reason that i am not getting oscillation
> with
>> > working crystal
>>
>> Are you *sure* the leads are properly soldered to the pads? Remove
> any flux,
>> it might be conductive. Chip might be faulty.
>>
>> Leon
>> --
>> Leon Heller, G1HSM
>> leon.heller@...
>> http://www.geocities.com/leon_heller
>>
>
>
> hi,
>       Thanks once again.
>       Chip might be faulty.
>       Is there is any chance of this thing.
>       Because out of 50 boards i am facing this problem on nearly
> more than 5 boards.

I could understand it with one board, but it's *very* unlikely with five 
boards. Those 32 kHz crystals can cause more problems than the 
high-frequency ones. - the feedback capacitors might need to be altered for 
the crystal characteristics (load capacitance and series resistance) and 
stray capacitance with your layout.

Leon