External crystal 32.768KHz ( msp430 )

selva kumar

Other Parts Discussed in Thread: MSP430F5659

Hi,

If external crystal(32.768kHz) is not there then what is the impact on the system. In our project we are using MSP430F5659 controller for NFC.

Kindly provide me with your suggestions.

Thank you,

over 8 years ago

0 Dennis Eichmann over 8 years ago

Guru 74080 points

Selva,

Have a look in the user's guide, chapter 5 Unified Clock System (page 158 and following).

Dennis

0 selva kumar over 8 years ago in reply to Dennis Eichmann

Prodigy 40 points

Hi Dennis,

I gone through that document, but i'm not able to conclude for the above query.

Regards,

Selva

0 Clemens Ladisch over 8 years ago in reply to selva kumar

Guru 242930 points

What exaclty do you mean with "not there"? Does your hardware have a crystal, and you want to know what happens when it fails? Or do you want to build hardware that works both with and without a crystal?

0 selva kumar over 8 years ago in reply to Clemens Ladisch

Prodigy 40 points

i want to built a hardware that works both with and without a crystal, so i want to know whats the impact if external crystal is not there in the System.

0 Dennis Eichmann over 8 years ago in reply to selva kumar

Guru 74080 points

0 selva kumar over 8 years ago in reply to Dennis Eichmann

Prodigy 40 points

Hi Dennis,

I have gone through that.

But I need to know that if I use only internal clock(32.768khz) and don't use external clock, how will the Timers viz,..MCLK, ACLK and SMCLK work or will they not work as expected?

Also, whether current consumption changes if we have a system without external crystal(32.768khz)?

0 Christoph Dohrn over 8 years ago in reply to selva kumar

TI__Prodigy 735 points

Hi Selva,

if you don' have an external crystal present, you could use the REFO instead. That is a built in oscillator that is meant as a substitute in case you can't or don't want to use an external crystal.

It is not as accurate as an external watch crystal and needs a bit more supply current but you can save the costs for the crystal.

If you don't necessarily need the 32.768kHz, you could use a different internal clock as source for the ACLK, for example the VLO (typ. 9.4kHz) which is having a lower accuracy and higher spread but needs significantly less current.

Thanks and best regards,

Christoph

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External crystal 32.768KHz ( msp430 )