Tsvetan Usunov wrote:

> your interrupt routine can increment BasicTimer1 and it will make same
> effect as it was driven by the 32kHz clock ;)
> no need to drive pins
> of course this is dirty last minute patch if you already have boards
> produced and strike the problem above, the more elegant solution is to
> improve board layout and cleaning procedures

I'll try it out. I don't regard a permanent software solution as 
inelegant, it sounds rather attractive to me. Your solution would be the 
cheapest of all I have looked at.

Thanks,
Mike.

-- 
Mike Page BEng(Hons) MIEE           www.eclectic-web.co.uk

> > another software "patch" of the problem is to run timer to do
> > interrupts with some frequency and to toggle LCD clock inside
> > interrupt routine, but this will increase your power requirements for
> > the application as you will frequently wake up the uC with the timer
> > interrupts
> 
> When you say "toggle LCD clock", do you mean to manually increment 
> BasicTimer1 which provides the LCD clock ? That would be interesting if 
> it worked.
> 
> Or manually drive the LCD pins ? I'm not planning to do that.

your interrupt routine can increment BasicTimer1 and it will make same
effect as it was driven by the 32kHz clock ;)
no need to drive pins
of course this is dirty last minute patch if you already have boards
produced and strike the problem above, the more elegant solution is to
improve board layout and cleaning procedures

Best regards
Tsvetan
---
PCB prototypes for $26 at http://run.to/pcb
(http://www.olimex.com/pcb)
Development boards for ARM, AVR, PIC, and MSP430 
(http://www.olimex.com/dev)

Jim Granville wrote:

>  Check if the pins try and self bias, and try a capacitive divider,
> or a series R / parallel C, from the 4060 to the 32Khz pin.
>  Check what the waveforms are when using a xtal, and that will
> give you an idea of the signal levels the OSC buffers expect.
>  Use a 100:1 probe, as they have lower C than 10:1
> -jg
> 

Just an update.

I have got this working on the bench at 28800Hz - thanks for the idea. 
After some experimentation I found tying both crystal pins together with 
100pF to ground and driving through 1M works fine with some margin. I 
will be including fallback positions on the PCB in case I run into 
trouble in preproduction.

Thanks again,
Mike.

-- 
Mike Page BEng(Hons) MIEE           www.eclectic-web.co.uk

Jim Granville wrote:
> Mike Page wrote:
> 
>> Hi All,
>>
>> On any other chip external clocking would be a very simple thing, but 
>> not on the MSP430F437 it seems. Has anyone managed to externally clock 
>> XT1 with 32kHz (or thereabouts ?) I am having trouble with the chip 
>> giving me LFOF and shutting off ACLK (which is the whole reason for 
>> clocking XT1 - I'm using the LCD). Works just fine with a watch 
>> crystal, but I want to dispense with it and use an external 4060.
> 
> 
>  I have not used a MSP430, but 32Khz OSC circuits are often
> amplitude controlled, and of very high impedance.
>  Check if the pins try and self bias, and try a capacitive divider,
> or a series R / parallel C, from the 4060 to the 32Khz pin.
>  Check what the waveforms are when using a xtal, and that will
> give you an idea of the signal levels the OSC buffers expect.
>  Use a 100:1 probe, as they have lower C than 10:1
> -jg
> 

That's interesting; I might give it a go.

Regards,
Mike.

-- 
Mike Page BEng(Hons) MIEE           www.eclectic-web.co.uk

Tsvetan Usunov wrote:

> Mike Page <mike@SCRUBeclectic-CAPSweb.BLAMEco.SWENuk> wrote in message news:<1078172777.266919@ananke.eclipse.net.uk>...
> 
>>Hi All,
>>
>>On any other chip external clocking would be a very simple thing, but 
>>not on the MSP430F437 it seems. Has anyone managed to externally clock 
>>XT1 with 32kHz (or thereabouts ?) 
> 

> another software "patch" of the problem is to run timer to do
> interrupts with some frequency and to toggle LCD clock inside
> interrupt routine, but this will increase your power requirements for
> the application as you will frequently wake up the uC with the timer
> interrupts

When you say "toggle LCD clock", do you mean to manually increment 
BasicTimer1 which provides the LCD clock ? That would be interesting if 
it worked.

Or manually drive the LCD pins ? I'm not planning to do that.

Regards,
Mike.

-- 
Mike Page BEng(Hons) MIEE           www.eclectic-web.co.uk

Mike Page wrote:
> Hi All,
> 
> On any other chip external clocking would be a very simple thing, but 
> not on the MSP430F437 it seems. Has anyone managed to externally clock 
> XT1 with 32kHz (or thereabouts ?) I am having trouble with the chip 
> giving me LFOF and shutting off ACLK (which is the whole reason for 
> clocking XT1 - I'm using the LCD). Works just fine with a watch crystal, 
> but I want to dispense with it and use an external 4060.

  I have not used a MSP430, but 32Khz OSC circuits are often
amplitude controlled, and of very high impedance.
  Check if the pins try and self bias, and try a capacitive divider,
or a series R / parallel C, from the 4060 to the 32Khz pin.
  Check what the waveforms are when using a xtal, and that will
give you an idea of the signal levels the OSC buffers expect.
  Use a 100:1 probe, as they have lower C than 10:1
-jg

Mike Page <mike@SCRUBeclectic-CAPSweb.BLAMEco.SWENuk> wrote in message news:<1078172777.266919@ananke.eclipse.net.uk>...
> Hi All,
> 
> On any other chip external clocking would be a very simple thing, but 
> not on the MSP430F437 it seems. Has anyone managed to externally clock 
> XT1 with 32kHz (or thereabouts ?) I am having trouble with the chip 
> giving me LFOF and shutting off ACLK (which is the whole reason for 
> clocking XT1 - I'm using the LCD). Works just fine with a watch crystal, 
> but I want to dispense with it and use an external 4060.
> 
> For technical reasons I can't use just XT1 and the FLL. The DCO 
> generates too much PWM jitter for my application. And for unknown 
> reasons the LCD drive is quite inflexible in its choice of clock source, 
> so I can't just hook my X MHz crystal up to XT1 either.
> 
> TIA,
> Mike.

Hi,

we have the same problems with MSP430F449 boards, the 32kHz oscillator
is very high impedance and all problems are mostly caused by not good
cleaning of the PCB after soldering (we changed also our PCB routing 3
times until we make it less sensitive).
If your oscillator is not starting just re-clean the PCBs, after that
try to avoid finger tip touching around 32kHz crystal area, board
which works ok stop after you touch the 32 kHz oscillator with finger
and start working again after clean it!

F44x series are with the worse oscillator circuit from the whole
MSP430 family all other members have no such problems

you can check Texas Instrument's PCB crystal layout recommendations
for MSP430 family which is on our web site:
http://www.olimex.com/dev/pdf/MSPPCB.pdf

another software "patch" of the problem is to run timer to do
interrupts with some frequency and to toggle LCD clock inside
interrupt routine, but this will increase your power requirements for
the application as you will frequently wake up the uC with the timer
interrupts

Best regards
Tsvetan
---
PCB prototypes for $26 at http://run.to/pcb
(http://www.olimex.com/pcb)
Development boards for ARM, AVR, PIC, and MSP430 
(http://www.olimex.com/dev)

Hi Mike!

What is your external clock frequency? It must be in the range 
450kHz~8MHz. And think about the osc fault management: osc failure is so 
sensitive that it triggers if you apply an oscilloscope to the clock 
source and even if you touch the contacts with your fingers.

Andreas

Hi All,

On any other chip external clocking would be a very simple thing, but 
not on the MSP430F437 it seems. Has anyone managed to externally clock 
XT1 with 32kHz (or thereabouts ?) I am having trouble with the chip 
giving me LFOF and shutting off ACLK (which is the whole reason for 
clocking XT1 - I'm using the LCD). Works just fine with a watch crystal, 
but I want to dispense with it and use an external 4060.

For technical reasons I can't use just XT1 and the FLL. The DCO 
generates too much PWM jitter for my application. And for unknown 
reasons the LCD drive is quite inflexible in its choice of clock source, 
so I can't just hook my X MHz crystal up to XT1 either.

TIA,
Mike.

-- 
Mike Page BEng(Hons) MIEE           www.eclectic-web.co.uk