Prototype using MC9S12XEP100 and recommendations of hardware

[danielflor]

Hello,

I'm designing a prototype that uses the MC9S12XEP100 microcontroller. I took into account the following documents:

• AN3262 - Designing Hardware for the MC9S12X D-Family
• EVB9S12XEP100 Schematic and Bill of Material
• MC9S12XEP100 Reference Manual Covers MC9S12XE Family

It seems to be unfeasible to follow all the recommendations and make full use of all the microcontroller pins. So,I have some doubts:

1) In Appendix C of the Reference Manual there is a recommended layout, which seems to be impossible to follow when using all the microcontroller pins. The distance recommendations made in AN3262 for components such as decoupling capacitors and recomendations to ground planes and signal are not viable this way. I have the EVB9S12XEP100 schematic, however, I do not have the layout, would you have the layout of this board available, even if in PDF? It could help a lot.

2) There would be problem to rout signals below the microcontroller? I mean, can exist signal tracks below the microcontroller ? If can not exists sinals and vias below the microcontroller, Can I do a GND plane below it ?

3) I noticed that the EVB9S12XEP100 board allows FSP configuration for oscillator. But, to facilitate the design of the board, I am thinking to disregard it and leave the LCP configuration instead, which is simpler and with fewer components. What would be the limitation that this decision could bring?

With my best regards,

Daniel.

[danielmartynek · Accepted solution]

Hello danielflor,

1.

You can refer to the layout of the S12XE DEVKIT, the files are available here:
https://www.nxp.com/design/development-boards/automotive-development-platforms/s12-magniv-mcu-platf/...

2.

You can route signal under the MCU and use a GND plane. 
Again, you can refer to the layout above.

3.
The LCP has lower noise emission than the FSP.
On the other hand, the LCP is more susceptible to external noise.

Regards,

Daniel