Thank you Kris for your valuable contribution about ESR of cristals.
Anyway I choose not to use LPM4 I order to avoid the stop of the LFXT1.
Claude
Le 04.03.2007 21:48, Microbit a rit :
>Hi,
>
>
>
>>Sometimes the quartz oscillates on 3rd harmonic, other times the frequency
>>is ok but the duty cycle is about 20% whitch is unusable for my
application.
>>
>>A crystal shifting to Third overtone (if in a classic Pierce Osc like on
MCUs)
>generally is a _significant_ tell tale sign of poor quality crystal.
>I would question this first. See if you can obtain specs on the crystal, or
find
>out what its ESR is. I would bet on the fact that this is the issue.
>Cheap high volume crystals tend to be cheap by having poor ESR, I've seen
this so many times !
>
>With such low frequency crystals as 32 kHz the problem is compounded.
>Try to get a crystal that you _know_ is good quality (ie. well within spec on
ESR) and run the
>same code with it.
>If you still have the problem (which I doubt) then something's iffy in the
start up sequencing
>of the oscillator.
>
>
>
>>experimented the 4 possibilities with the internal capacitors. I also
>>tried with various values of external capacitors. In any case the
>>
>>There's no point in that.
>You will find that the flipping to 3rd overtone might stop with specific values
of load caps
>(actually, the phase shift cap), but then it's guaranteed that with
different crystals the problem
>will reappear in production.
>
>Regardless of outcome, I would advise low ESR crystals are used, especially for
DFM.
>HW designers tend to be to casual about crystals and their use in MCUs (aka
ignorant).
>
>HTH
>Best Regards,
>Kris
>
>-----Original Message-----
>From: m... [mailto:m...] On Behalf Of cl.buchilly
>Sent: Tuesday, 27 February 2007 7:03 PM
>To: m...
>Subject: [msp430] LPM4 and LFXT1
>
>When I use the LPM4 mode with a msp430F417 I have no problem to
>wake-up the processor but when I use the same software with a
>msp430F437, the LFXT1 oscillator no longer work properly after wake-up
>from LPM4. The only way to restart it properly is to power off the
>processor.
>
>More details:
>The quartz connected to XIN / Xout is a 32kHz.
>After LPM4, I do a PUC using the Watchdog register. I have
>experimented the 4 possibilities with the internal capacitors. I also
>tried with various values of external capacitors. In any case the
>signal at pin ACLK (pin 62) is not correct. Sometimes the quartz
>oscillates on 3rd harmonic, other times the frequency is ok but the
>duty cycle is about 20% whitch is unusable for my application.
>
>The error is systematic. The oscillator always works properly after
>power up, but never works properly after LPM4 + PUC. There is no
>problem after LPM3 + PUC (because the LFXT1 doesn't stop with LPM3).
>
>Has any of you something to suggest?
>Yahoo! Groups Links
>
>
>
LPM4 and LFXT1
Started by ●March 4, 2007
Reply by ●March 8, 20072007-03-08
Reply by ●March 8, 20072007-03-08
Thank you very much for your suggestions.
As I have not enough time for the moment I took your 2nd suggestion.
But as soon as I would have time I will try your first one.
Claude
Le 05.03.2007 05:15, old_cow_yellow a rit :
>While I agree with Microbit that you may need a better crystal, I
>suggest that you also consider the following two ideas.
>
>One idea is, before go to LPM4, change all clock module registers to
>their PUC settings. After wake up from LPM4, first wait for LFXT1 to
>stabilize before changing the clock module resisters to the settings
>you want.
>
>The other idea is, do not use LPM4. Use LPM3 instead. The difference
>between the two modes is less than 2 uA. The LFXT1 takes hundreds of
>milli-seconds to start (if it starts at all); it is hardly worth the
>long wait to save 2 uA (17 mAHr per year).
>
>--- In m..., "Microbit" wrote:
>
>
>>Hi,
>>
>>
>>
>>>Sometimes the quartz oscillates on 3rd harmonic, other times the
>>>
>>>
>frequency
>
>
>>>is ok but the duty cycle is about 20% whitch is unusable for my
>>>
>>>
>application.
>
>
>>A crystal shifting to Third overtone (if in a classic Pierce Osc
>>
>>
>like on MCUs)
>
>
>>generally is a _significant_ tell tale sign of poor quality crystal.
>>I would question this first. See if you can obtain specs on the
>>
>>
>crystal, or find
>
>
>>out what its ESR is. I would bet on the fact that this is the issue.
>>Cheap high volume crystals tend to be cheap by having poor ESR,
>>
>>
>I've seen this so many times !
>
>
>>With such low frequency crystals as 32 kHz the problem is
>>
>>
>compounded.
>
>
>>Try to get a crystal that you _know_ is good quality (ie. well
>>
>>
>within spec on ESR) and run the
>
>
>>same code with it.
>>If you still have the problem (which I doubt) then something's iffy
>>
>>
>in the start up sequencing
>
>
>>of the oscillator.
>>
>>
>>
>>>experimented the 4 possibilities with the internal capacitors. I
>>>
>>>
>also
>
>
>>>tried with various values of external capacitors. In any case the
>>>
>>>
>>There's no point in that.
>>You will find that the flipping to 3rd overtone might stop with
>>
>>
>specific values of load caps
>
>
>>(actually, the phase shift cap), but then it's guaranteed that with
>>
>>
>different crystals the problem
>
>
>>will reappear in production.
>>
>>Regardless of outcome, I would advise low ESR crystals are used,
>>
>>
>especially for DFM.
>
>
>>HW designers tend to be to casual about crystals and their use in
>>
>>
>MCUs (aka ignorant).
>
>
>>HTH
>>Best Regards,
>>Kris
>>
>>-----Original Message-----
>>From: m... [mailto:m...] On
>>
>>
>Behalf Of cl.buchilly
>
>
>>Sent: Tuesday, 27 February 2007 7:03 PM
>>To: m...
>>Subject: [msp430] LPM4 and LFXT1
>>
>>When I use the LPM4 mode with a msp430F417 I have no problem to
>>wake-up the processor but when I use the same software with a
>>msp430F437, the LFXT1 oscillator no longer work properly after wake-
>>
>>
>up
>
>
>>from LPM4. The only way to restart it properly is to power off the
>>processor.
>>
>>More details:
>>The quartz connected to XIN / Xout is a 32kHz.
>>After LPM4, I do a PUC using the Watchdog register. I have
>>experimented the 4 possibilities with the internal capacitors. I
>>
>>
>also
>
>
>>tried with various values of external capacitors. In any case the
>>signal at pin ACLK (pin 62) is not correct. Sometimes the quartz
>>oscillates on 3rd harmonic, other times the frequency is ok but the
>>duty cycle is about 20% whitch is unusable for my application.
>>
>>The error is systematic. The oscillator always works properly after
>>power up, but never works properly after LPM4 + PUC. There is no
>>problem after LPM3 + PUC (because the LFXT1 doesn't stop with LPM3).
>>
>>Has any of you something to suggest?
>>Yahoo! Groups Links
>>
>>
>>
>
As I have not enough time for the moment I took your 2nd suggestion.
But as soon as I would have time I will try your first one.
Claude
Le 05.03.2007 05:15, old_cow_yellow a rit :
>While I agree with Microbit that you may need a better crystal, I
>suggest that you also consider the following two ideas.
>
>One idea is, before go to LPM4, change all clock module registers to
>their PUC settings. After wake up from LPM4, first wait for LFXT1 to
>stabilize before changing the clock module resisters to the settings
>you want.
>
>The other idea is, do not use LPM4. Use LPM3 instead. The difference
>between the two modes is less than 2 uA. The LFXT1 takes hundreds of
>milli-seconds to start (if it starts at all); it is hardly worth the
>long wait to save 2 uA (17 mAHr per year).
>
>--- In m..., "Microbit" wrote:
>
>
>>Hi,
>>
>>
>>
>>>Sometimes the quartz oscillates on 3rd harmonic, other times the
>>>
>>>
>frequency
>
>
>>>is ok but the duty cycle is about 20% whitch is unusable for my
>>>
>>>
>application.
>
>
>>A crystal shifting to Third overtone (if in a classic Pierce Osc
>>
>>
>like on MCUs)
>
>
>>generally is a _significant_ tell tale sign of poor quality crystal.
>>I would question this first. See if you can obtain specs on the
>>
>>
>crystal, or find
>
>
>>out what its ESR is. I would bet on the fact that this is the issue.
>>Cheap high volume crystals tend to be cheap by having poor ESR,
>>
>>
>I've seen this so many times !
>
>
>>With such low frequency crystals as 32 kHz the problem is
>>
>>
>compounded.
>
>
>>Try to get a crystal that you _know_ is good quality (ie. well
>>
>>
>within spec on ESR) and run the
>
>
>>same code with it.
>>If you still have the problem (which I doubt) then something's iffy
>>
>>
>in the start up sequencing
>
>
>>of the oscillator.
>>
>>
>>
>>>experimented the 4 possibilities with the internal capacitors. I
>>>
>>>
>also
>
>
>>>tried with various values of external capacitors. In any case the
>>>
>>>
>>There's no point in that.
>>You will find that the flipping to 3rd overtone might stop with
>>
>>
>specific values of load caps
>
>
>>(actually, the phase shift cap), but then it's guaranteed that with
>>
>>
>different crystals the problem
>
>
>>will reappear in production.
>>
>>Regardless of outcome, I would advise low ESR crystals are used,
>>
>>
>especially for DFM.
>
>
>>HW designers tend to be to casual about crystals and their use in
>>
>>
>MCUs (aka ignorant).
>
>
>>HTH
>>Best Regards,
>>Kris
>>
>>-----Original Message-----
>>From: m... [mailto:m...] On
>>
>>
>Behalf Of cl.buchilly
>
>
>>Sent: Tuesday, 27 February 2007 7:03 PM
>>To: m...
>>Subject: [msp430] LPM4 and LFXT1
>>
>>When I use the LPM4 mode with a msp430F417 I have no problem to
>>wake-up the processor but when I use the same software with a
>>msp430F437, the LFXT1 oscillator no longer work properly after wake-
>>
>>
>up
>
>
>>from LPM4. The only way to restart it properly is to power off the
>>processor.
>>
>>More details:
>>The quartz connected to XIN / Xout is a 32kHz.
>>After LPM4, I do a PUC using the Watchdog register. I have
>>experimented the 4 possibilities with the internal capacitors. I
>>
>>
>also
>
>
>>tried with various values of external capacitors. In any case the
>>signal at pin ACLK (pin 62) is not correct. Sometimes the quartz
>>oscillates on 3rd harmonic, other times the frequency is ok but the
>>duty cycle is about 20% whitch is unusable for my application.
>>
>>The error is systematic. The oscillator always works properly after
>>power up, but never works properly after LPM4 + PUC. There is no
>>problem after LPM3 + PUC (because the LFXT1 doesn't stop with LPM3).
>>
>>Has any of you something to suggest?
>>Yahoo! Groups Links
>>
>>
>>
>
Reply by ●March 9, 20072007-03-09
D'accord :-)
You're welcome.
"Du vin, du pain, Boursin" :-)
Best Regards,
Kris
-----Original Message-----
From: m... [mailto:m...] On Behalf Of Claude Buchilly
Sent: Friday, 9 March 2007 3:19 AM
To: m...
Subject: Re: [msp430] LPM4 and LFXT1
Thank you Kris for your valuable contribution about ESR of cristals.
Anyway I choose not to use LPM4 I order to avoid the stop of the LFXT1.
Claude
Le 04.03.2007 21:48, Microbit a rit :
>Hi,
>
>
>
>>Sometimes the quartz oscillates on 3rd harmonic, other times the frequency
>>is ok but the duty cycle is about 20% whitch is unusable for my application.
>>
>>A crystal shifting to Third overtone (if in a classic Pierce Osc like on MCUs)
>generally is a _significant_ tell tale sign of poor quality crystal.
>I would question this first. See if you can obtain specs on the crystal, or find
>out what its ESR is. I would bet on the fact that this is the issue.
>Cheap high volume crystals tend to be cheap by having poor ESR, I've seen this so many times !
>
>With such low frequency crystals as 32 kHz the problem is compounded.
>Try to get a crystal that you _know_ is good quality (ie. well within spec on ESR) and run the
>same code with it.
>If you still have the problem (which I doubt) then something's iffy in the start up sequencing
>of the oscillator.
>
>
>
>>experimented the 4 possibilities with the internal capacitors. I also
>>tried with various values of external capacitors. In any case the
>>
>>There's no point in that.
>You will find that the flipping to 3rd overtone might stop with specific values of load caps
>(actually, the phase shift cap), but then it's guaranteed that with different crystals the
problem
>will reappear in production.
>
>Regardless of outcome, I would advise low ESR crystals are used, especially for DFM.
>HW designers tend to be to casual about crystals and their use in MCUs (aka ignorant).
>
>HTH
>Best Regards,
>Kris
>
>-----Original Message-----
>From: m... [mailto:m...] On Behalf Of cl.buchilly
>Sent: Tuesday, 27 February 2007 7:03 PM
>To: m...
>Subject: [msp430] LPM4 and LFXT1
>
>When I use the LPM4 mode with a msp430F417 I have no problem to
>wake-up the processor but when I use the same software with a
>msp430F437, the LFXT1 oscillator no longer work properly after wake-up
>from LPM4. The only way to restart it properly is to power off the
>processor.
>
>More details:
>The quartz connected to XIN / Xout is a 32kHz.
>After LPM4, I do a PUC using the Watchdog register. I have
>experimented the 4 possibilities with the internal capacitors. I also
>tried with various values of external capacitors. In any case the
>signal at pin ACLK (pin 62) is not correct. Sometimes the quartz
>oscillates on 3rd harmonic, other times the frequency is ok but the
>duty cycle is about 20% whitch is unusable for my application.
>
>The error is systematic. The oscillator always works properly after
>power up, but never works properly after LPM4 + PUC. There is no
>problem after LPM3 + PUC (because the LFXT1 doesn't stop with LPM3).
>
>Has any of you something to suggest?
>Yahoo! Groups Links
>
>
>
Yahoo! Groups Links
You're welcome.
"Du vin, du pain, Boursin" :-)
Best Regards,
Kris
-----Original Message-----
From: m... [mailto:m...] On Behalf Of Claude Buchilly
Sent: Friday, 9 March 2007 3:19 AM
To: m...
Subject: Re: [msp430] LPM4 and LFXT1
Thank you Kris for your valuable contribution about ESR of cristals.
Anyway I choose not to use LPM4 I order to avoid the stop of the LFXT1.
Claude
Le 04.03.2007 21:48, Microbit a rit :
>Hi,
>
>
>
>>Sometimes the quartz oscillates on 3rd harmonic, other times the frequency
>>is ok but the duty cycle is about 20% whitch is unusable for my application.
>>
>>A crystal shifting to Third overtone (if in a classic Pierce Osc like on MCUs)
>generally is a _significant_ tell tale sign of poor quality crystal.
>I would question this first. See if you can obtain specs on the crystal, or find
>out what its ESR is. I would bet on the fact that this is the issue.
>Cheap high volume crystals tend to be cheap by having poor ESR, I've seen this so many times !
>
>With such low frequency crystals as 32 kHz the problem is compounded.
>Try to get a crystal that you _know_ is good quality (ie. well within spec on ESR) and run the
>same code with it.
>If you still have the problem (which I doubt) then something's iffy in the start up sequencing
>of the oscillator.
>
>
>
>>experimented the 4 possibilities with the internal capacitors. I also
>>tried with various values of external capacitors. In any case the
>>
>>There's no point in that.
>You will find that the flipping to 3rd overtone might stop with specific values of load caps
>(actually, the phase shift cap), but then it's guaranteed that with different crystals the
problem
>will reappear in production.
>
>Regardless of outcome, I would advise low ESR crystals are used, especially for DFM.
>HW designers tend to be to casual about crystals and their use in MCUs (aka ignorant).
>
>HTH
>Best Regards,
>Kris
>
>-----Original Message-----
>From: m... [mailto:m...] On Behalf Of cl.buchilly
>Sent: Tuesday, 27 February 2007 7:03 PM
>To: m...
>Subject: [msp430] LPM4 and LFXT1
>
>When I use the LPM4 mode with a msp430F417 I have no problem to
>wake-up the processor but when I use the same software with a
>msp430F437, the LFXT1 oscillator no longer work properly after wake-up
>from LPM4. The only way to restart it properly is to power off the
>processor.
>
>More details:
>The quartz connected to XIN / Xout is a 32kHz.
>After LPM4, I do a PUC using the Watchdog register. I have
>experimented the 4 possibilities with the internal capacitors. I also
>tried with various values of external capacitors. In any case the
>signal at pin ACLK (pin 62) is not correct. Sometimes the quartz
>oscillates on 3rd harmonic, other times the frequency is ok but the
>duty cycle is about 20% whitch is unusable for my application.
>
>The error is systematic. The oscillator always works properly after
>power up, but never works properly after LPM4 + PUC. There is no
>problem after LPM3 + PUC (because the LFXT1 doesn't stop with LPM3).
>
>Has any of you something to suggest?
>Yahoo! Groups Links
>
>
>
Yahoo! Groups Links
