thanks..guys!!
You have to evaluate how well it works based on what you need to do. I'm currently using this family in an application with a bus frequency <4 Mhz where two 4th order polynomials using ieee32 math are being evaluated ~4 times a second while sending and receiving serial messages at 115200 and collecting ADC samples at ~20Hz and have no problems.
you can use floating point support in your hcs12x project. but please note floating point lib is very memory consumming, the floating lib supported project will generate bigger code size burning image after build.
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Best Regards,
ZhangJun