S12 / MagniV MicrocontrollersのトピックRe: How use pierce oscillator on µc MC9S12A128CPV ?

How use pierce oscillator on µc MC9S12A128CPV ?

erwancoton — Wed, 27 Apr 2016 15:17:00 GMT

I use 16MHz quartz with 22pFfor each capacitor (cf schematic in attached)

But I've no frequency on the EXTAL pin.

May be I did something wrong ?

need help please.

Re: How use pierce oscillator on µc MC9S12A128CPV ?

RadekS — Thu, 12 May 2016 12:58:14 GMT

Hi Erwan,

I suppose that this thread is related to your next thread:

https://community.freescale.com/thread/391931

Yes, MC9S12A128CPVE should work with the oscillator in Pierce mode.

In that case, the XCLKS=PE7 pin has to be connected (pulled-down) to GND.

I would like to recommend additional parallel resistor to crystal – for example, 1MOhm. However, this will be probably not the root cause.

The crystal circuit parts parameters should be evaluated with crystal manufacturer. But 22pF looks OK for most of the standard crystals.

Note: Crystal must be fundamental and not overtone.

Could you please share your schematic with MCU surroundings that we could shortly check for any obvious or potential issues?

Please check power supply pins according to Table 2-2 MC9S12DT128 Power and Ground Connection Summary in RM:

http://www.nxp.com/files/microcontrollers/doc/data_sheet/9S12DT128_ZIP.zip

Please check also chip orientation.

I hope it helps you.

Have a great day,
RadekS

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Re: How use pierce oscillator on µc MC9S12A128CPV ?

erwancoton — Thu, 12 May 2016 16:16:23 GMT

Hi radeks,

Thank you for your reply.

Now, it’s ok with 1M in parallel on the crystal.

Have a good day

Erwan

De : RadekS

Envoyé : jeudi 12 mai 2016 14:59

À : Erwan Coton <ecoton@lea-photonics.com>

Objet : Re: - How use pierce oscillator on µc MC9S12A128CPV ?

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How use pierce oscillator on µc MC9S12A128CPV ?

reply from Radek Sestak <https://community.freescale.com/people/RadekS?et=watches.email.thread> in S12 / MagniV Microcontrollers - View the full discussion <https://community.freescale.com/message/644481?et=watches.email.thread#comment-644481>