Hi!

I have problems to run the MSP430F1121 with a 32khz watch crystal. It
oscillates only with an amplitude of 300mV around VCC. I have connected the
crystal  without external capacitators and used the following code to
activate the LF mode :

void vClockInit( void ){
     WDTCTL = WDTPW + WDTHOLD;     /* disable Watchdog  */
     BCSCTL1 &= ~0x30;            //select low-frequencymode, ACKL-Divider 1
     BCSCTL2 = 0xC8;               /* set MCLKLK*/
     }

I also added external capacitators (33pF), but I achieved the same results.
Does anybody has a sample code for running the LFXT1 in LF-mode for the gcc
compiler? Is it necessary to add the 5.1M resistor? (Vcc=3V)

Thanks in advance

best regards
Jan

Somewhere I've read, that it's not possible to source MCLK from
32kHz 
crystal. Try source MCLK from DCO and peripheral from ACLK.

Jano

--- In msp430@msp4..., "Jan Stumpf" <jan@e...> wrote:
> Hi!
> 
> I have problems to run the MSP430F1121 with a 32khz watch crystal. 
It
> oscillates only with an amplitude of 300mV around
VCC. I have 
connected the
> crystal  without external capacitators and used
the following code 
to
> activate the LF mode :
> 
> void vClockInit( void ){
>      WDTCTL = WDTPW + WDTHOLD;     /* disable Watchdog  */
>      BCSCTL1 &= ~0x30;            //select low-frequencymode, ACKL-
Divider > 1
>      BCSCTL2 = 0xC8;               /* set
MCLKLK*/
>      }
> 
> I also added external capacitators (33pF), but I achieved the same 
results.
> Does anybody has a sample code for running the
LFXT1 in LF-mode for 
the gcc
> compiler? Is it necessary to add the 5.1M
resistor? (Vcc=3V)
> 
> Thanks in advance
> 
> best regards
> Jan

At 12:55 PM 19/04/2004, you wrote:

In the user guide - slau049d.pdf, page 124, there is a software routine for 
setting the MCLK from LFTxtal.

Good luck


Peter
>Somewhere I've read, that it's not
possible to source MCLK from 32kHz
>crystal. Try source MCLK from DCO and peripheral from ACLK.
>
>Jano
>
>--- In msp430@msp4..., "Jan Stumpf" <jan@e...> wrote:
> > Hi!
> >
> > I have problems to run the MSP430F1121 with a 32khz watch crystal.
>It
> > oscillates only with an amplitude of 300mV around VCC. I have
>connected the
> > crystal  without external capacitators and used the following code
>to
> > activate the LF mode :
> >
> > void vClockInit( void ){
> >      WDTCTL = WDTPW + WDTHOLD;     /* disable Watchdog  */
> >      BCSCTL1 &= ~0x30;            //select low-frequencymode,
ACKL-
>Divider > > 1
> >      BCSCTL2 = 0xC8;               /* set MCLKLK*/
> >      }
> >
> > I also added external capacitators (33pF), but I achieved the same
>results.
> > Does anybody has a sample code for running the LFXT1 in LF-mode for
>the gcc
> > compiler? Is it necessary to add the 5.1M resistor? (Vcc=3V)
> >
> > Thanks in advance
> >
> > best regards
> > Jan
>
>
>
>.
>
>
>Yahoo! Groups Links
>
>
>
>

Hi,

i'm using the MSP430F149 with 32.768 kHz MCLK without problems.
This makes the MC really slow but it works.

Rolf

janko20022001 schrieb:

>Somewhere I've read, that it's not
possible to source MCLK from 32kHz 
>crystal. Try source MCLK from DCO and peripheral from ACLK.
>
>Jano
>
>--- In msp430@msp4..., "Jan Stumpf" <jan@e...> wrote:
>  
>
>>Hi!
>>
>>I have problems to run the MSP430F1121 with a 32khz watch crystal. 
>>    
>>
>It
>  
>
>>oscillates only with an amplitude of 300mV around VCC. I have 
>>    
>>
>connected the
>  
>
>>crystal  without external capacitators and used the following code 
>>    
>>
>to
>  
>
>>activate the LF mode :
>>
>>void vClockInit( void ){
>>     WDTCTL = WDTPW + WDTHOLD;     /* disable Watchdog  */
>>     BCSCTL1 &= ~0x30;            //select low-frequencymode, ACKL-
>>    
>>
>Divider >  
>
>>1
>>     BCSCTL2 = 0xC8;               /* set MCLKLK*/
>>     }
>>
>>I also added external capacitators (33pF), but I achieved the same 
>>    
>>
>results.
>  
>
>>Does anybody has a sample code for running the LFXT1 in LF-mode for 
>>    
>>
>the gcc
>  
>
>>compiler? Is it necessary to add the 5.1M resistor? (Vcc=3V)
>>
>>Thanks in advance
>>
>>best regards
>>Jan
>>    
>>
>
>
>
>.
>
> 
>Yahoo! Groups Links
>
>
>
> 
>
>
>  
>