/XCLKS Is direct grounding OK?

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/XCLKS Is direct grounding OK?

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Contributor I

My CPU is mc9s12xe series,The external crystal oscillator is used。

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NXP TechSupport
NXP TechSupport

Hello,

To configure the the oscillator for Full Swing Pierce or for an external clock source, the pin must read LOW during rising edge of the reset pin signal.

It can be either driven or pulled externally. 

Please note that the the pin has an internal weak pullup enabled by default out of reset.

danielmartynek_0-1602665365520.png

So, if an external pull-down is used, it must be stronger than that to ensure the logic value and compensate for noise.

If the pin is connected to the ground directly, make sure the SW does not reconfigure the pin to GPIO Output and does not drive it HIGH.

 

Reference schematics for S12(X) devices:

https://community.nxp.com/t5/S12-MagniV-Microcontrollers/Reference-schematics-for-S12-X-devices/ta-p...

danielmartynek_1-1602665602931.png

 

Regards,

Daniel

 

 

 

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143 Views
NXP TechSupport
NXP TechSupport

Hello,

To configure the the oscillator for Full Swing Pierce or for an external clock source, the pin must read LOW during rising edge of the reset pin signal.

It can be either driven or pulled externally. 

Please note that the the pin has an internal weak pullup enabled by default out of reset.

danielmartynek_0-1602665365520.png

So, if an external pull-down is used, it must be stronger than that to ensure the logic value and compensate for noise.

If the pin is connected to the ground directly, make sure the SW does not reconfigure the pin to GPIO Output and does not drive it HIGH.

 

Reference schematics for S12(X) devices:

https://community.nxp.com/t5/S12-MagniV-Microcontrollers/Reference-schematics-for-S12-X-devices/ta-p...

danielmartynek_1-1602665602931.png

 

Regards,

Daniel

 

 

 

View solution in original post

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