MC9S12XS128MAA

[hhcao]

I am using the MC9S12XS128MAA microcontroller .When the frequency is set to 16M, the microcontroller works normally , but set to 80M, it could only run 3-5s,and then collapses. Microcontroller on the Minimum system board now I use has been burned before. Please help me find out the problem, thank you.

[lama]

Hi,

80MHz - What is this frequency generated from?

Is it BUSCLK or PLLCLK.

If you use PLL to set the frequency then maximum PLLCLK is 80MHz and maximum BUSCLK is 40MHz.

In order to use correct PLL setup you can use PLL calculator at the page http://www.freescale.com/webapp/sps/site/prod_summary.jsp?code=S12XE&fpsp=1&tab=Design_Tools_Tab

in the section Software Development Tools (33): S12XESW the file S12XE IPLL Calculator Software can be found.

Best regards,

Ladislav