68300

Hello,

We have a design using a 3.3V 68332 micro (MC68LK332ACFC16) and we are
experiencing a problem wherein on 2 boards so far, the micro stays in reset
after a power up because the 32,768KHz crystal is not oscillating.

I wonder if this is related to the attached message from Charles Melear
concerning a mask difference between the 5V and 3.3V devices in the PLL
area.

Is there a know  problem with the 3.3V device related to the PLL?

Tim McCormcik



 12/14/01
>Message sent by "Charles Melear" <rdph40@...>
 >to the 683xx Mailing List.

>Tim,

>I think that there may be a small tweek to the PLL but that is all.

>Charlie

>tmccormick@... wrote:
>
>  Message sent by tmccormick@...
>  to the 683xx Mailing List.
>
> Follow up question:
>
> Is the 3.3V device MC68LK332ACFC16 the same die also?
>
> Tim McCormick
>
>
>                     "Charles Melear"
>                     <rdph40@...>       To:
683xx@...
>                     Sent by:                         cc:
>                     owner-683xx@oakhill-csic.s       Subject:     Re: 25
MHz 68332 any diff?
>                     ps.mot.com
>
>
>                     12/12/01 04:58 PM
>                     Please respond to 683xx
>
>
>
>  Message sent by "Charles Melear" <rdph40@...>
>  to the 683xx Mailing List.
>
> Scott,
>
> You are the man.  You have all the bases covered with regard to using the
> High Stability
> Filter and all.
>
> Bye the bye, the 16, 20 and 25 MHz devices all come from the same die.
> There is NO - NADA
> - NYET difference between the devices.
>
> Here are two ideas.  First, does the oscillator fail to start?  This
would
> be indicated by
> the part never releasing reset and limp mode frequency (about 1.8 MHz) on
> Clockout.  The
> cure is to reduce the value of the series resistor on the crystal (the
330
> Kohm) until you
> see an 8 MHz signal on clock out about 200 to 400 milliseconds after
power
> is turned on.
> It is really hard to probe the crystal pins to see when the oscillator is
> starting because
> the scope probe really loads those crystal pins.  Look at Clockout
instead.
>
> Second, if you are changing the frequency to anything above 8 MHz, it is
> IMPERATIVE (like
> you MUST DO THIS) that the X bit in the SYNCR register be set to a logic
1.
> There is just
> no other alternative   -  well, there is none that will work.
>
> See where this gets you and post another message if this doesn't work.
>
> Regards,
>
> Charlie