68300

Hello everyone.

I have two questions to the clock generator of the MC68332CFC25MHz
with a 32,768 kHz reference.
Does somebody know the maximum of the clock freqency I can reach.
In my system the clock frequency is ok till 20,971Mhz. Higher values in the
sync-register, which forces greater frequencies than 20,971MHz are not
stable.
And the frequencies are not equal to the value I expected.

Is this normal effect, or could be something wrong with my device.

Thanks
Joachim

Joachim,
 
There are two problems that you need to be aware of.
 
1.  The only mask set of the MC68332 that is in production is J30C.  (J66A is an identical mask set made in another wafer line.)  For J30C and J66A, the 3-component XFC filter is required.  If you don't use the 3-component filter, your circuit will have clock jitter.  Sometimes it can get bad enough to mess up asynchronous serial communications devices and cause bit error problems.
 
2.  If you DO NOT set the X bit = 1 in the SYNCR register, the VCO will run too fast, lose lock and then all bets are off on what system frequency will result.  So, if you are going to run the system clock above 8.3 MHz, the X bit in the SYNCR register MUST (there are no other options here) be set to a logic 1.  Then, calculate the W and Y bits to get the frequency you want.
 
Let me know if this works.
 
Charlie

-----Original Message-----
From: Entwicklung [mailto:Entwicklung@...]
Sent: Monday, December 16, 2002 8:40 AM
To: 68300@yahoogroups.com
Subject: [68300] 68332 clock frequency


Hello everyone.

I have two questions to the clock generator of the MC68332CFC25MHz
with a 32,768 kHz reference.
Does somebody know the maximum of the clock freqency I can reach.
In my system the clock frequency is ok till 20,971Mhz. Higher values in the
sync-register, which forces greater frequencies than 20,971MHz are not
stable.
And the frequencies are not equal to the value I expected.

Is this normal effect, or could be something wrong with my device.

Thanks
Joachim


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[Non-text portions of this message have been removed]

Charlie,

After changing the X bit to 1 an the new W and Y values, the system
frequency is ok now.

Many thanks for your help.

Joachim



-----Urspr\ufffdngliche Nachricht-----
Von: "Melear Charles-rdph40" <charles.melear@...>
An: <68300@yahoogroups.com>
Gesendet: Montag, 16. Dezember 2002 15:50
Betreff: RE: [68300] 68332 clock frequency


> Joachim,
>
> There are two problems that you need to be aware of.
>
> 1.  The only mask set of the MC68332 that is in production is J30C.  (J66A
is an identical mask set made in another wafer line.)  For J30C and J66A,
the 3-component XFC filter is required.  If you don't use the 3-component
filter, your circuit will have clock jitter.  Sometimes it can get bad
enough to mess up asynchronous serial communications devices and cause bit
error problems.
>
> 2.  If you DO NOT set the X bit = 1 in the SYNCR register, the VCO will
run too fast, lose lock and then all bets are off on what system frequency
will result.  So, if you are going to run the system clock above 8.3 MHz,
the X bit in the SYNCR register MUST (there are no other options here) be
set to a logic 1.  Then, calculate the W and Y bits to get the frequency you
want.
>
> Let me know if this works.
>
> Charlie
>
> -----Original Message-----
> From: Entwicklung [mailto:Entwicklung@...]
> Sent: Monday, December 16, 2002 8:40 AM
> To: 68300@yahoogroups.com
> Subject: [68300] 68332 clock frequency
>
>
> Hello everyone.
>
> I have two questions to the clock generator of the MC68332CFC25MHz
> with a 32,768 kHz reference.
> Does somebody know the maximum of the clock freqency I can reach.
> In my system the clock frequency is ok till 20,971Mhz. Higher values in
the
> sync-register, which forces greater frequencies than 20,971MHz are not
> stable.
> And the frequencies are not equal to the value I expected.
>
> Is this normal effect, or could be something wrong with my device.
>
> Thanks
> Joachim
>
>
> ---------------------------------------------------
> To unsubscribe from this group, send an email to:
> 68300-unsubscribe@yahoogroups.com
>
> To learn more about Motorola Microcontrollers, please visit
> http://www.motorola.com/mcu <http://www.motorola.com/mcu>
>
>
>
> Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service
<http://docs.yahoo.com/info/terms/> .

>
>
>
>
> [Non-text portions of this message have been removed]
>
>
>
> ---------------------------------------------------
> To unsubscribe from this group, send an email to:
> 68300-unsubscribe@yahoogroups.com
>
> To learn more about Motorola Microcontrollers, please visit
> http://www.motorola.com/mcu
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>

Group.

We have just finished our 68332 project and have one real expert programmer 
looking for an assignment.  He is located in Southern California and 
probably cannot relocate but will be able to telecommute.  Anyone need help 
let me know.

Robert E. Yablonski
yabo@...