Crystal Circuit for MSp430g2553

varun perumal

Other Parts Discussed in Thread: MSP430G2553

Hi all,

I am trying to design a custom board for the msp430g2553, i could not find any information on adding an external crystal ( i want to add 16 Mhz or more) to the IC. Can someone point me to any sample circuits , board layout patterns and load capacitor selection . Also what is the maximum frequency of the crystal that i can use with the IC ? Can it be used without load capacitors?

Thanks in advance,

Varun

over 13 years ago

0 old_cow_yellow over 13 years ago

Guru 58965 points

What you try to do is one thing, what the chip is designed to do is a different matter. The fact you cannot find any information on doing so is an indication of this reality.

0 varun perumal over 13 years ago in reply to old_cow_yellow

Prodigy 110 points

I have found the following document on adding a 32KHz crystal, so i guess the chip does have support for an external crystal, but there is no information about supporting higher frequencies...

http://www.ti.com/lit/an/slaa322b/slaa322b.pdf

0 Istvan Cserny over 13 years ago in reply to varun perumal

Intellectual 505 points

varun perumal said:
but there is no information about supporting higher frequencies...

The Value Line series MSP430G2XXX microcontrollers don't have XT2 high frequency oscillator and the existing LFXT1 oscillator doesn't support the high frequency mode. The only possibility is to use an external oscillator (not just a crystal resonator). I'm not quite sure wheter is it officially supported, but there are hacker project around using this technique.

Best regards,

Istvan Cserny

0 varun perumal over 13 years ago

Prodigy 110 points

Thanks for the info, I think i will look at a couple of hacker projects that have been using an external high frequency crystal....

0 Istvan Cserny over 13 years ago in reply to varun perumal

Intellectual 505 points

varun perumal said:
hacker projects that have been using an external high frequency crystal....

Not crystal, but external oscillator...

See for example these:

LaunchPad On-board Off-chip 12MHz Clock

Precision 12 MHz clock for the Launchpad

0 varun perumal over 13 years ago in reply to Istvan Cserny

Prodigy 110 points

Got it . Thanks !!

0 Jens-Michael Gross over 13 years ago

Guru 227245 points

varun perumal said:
Also what is the maximum frequency of the crystal that i can use with the IC

The G sereis doesn't support high-frequency crystals. The datasheet lists a maximum crystal frequency of 50kHz (32768Hz typ) for the XT1 input.
Also, in bypass mode, the datasheet lists a maximum of 50kHz.

Youshould already have this information (reading the datasheet of a device is mandatory)

However, experiments have revealed that in bypass mdoe, the G series devices also accept high-frequency TTL square wave signals of several MHz.
But this is not officially supported and may be subject to change without notice.

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Crystal Circuit for MSp430g2553