Dear NXP stuff,
Now I have face one issue which has posted on another question ( has not been solved )
Re: FTM Input capture mode ( single edge / dual ed... - NXP Community
My BUS clock has been set to 60MHz and MCGFFCLK is 15MHz
and I am using FTM edge capture mode with eDMA to measure a input signal frequency.
according to the document "K64 Sub-Family Reference Manual" Kinetis K64: 120MHz Cortex-M4F up to 1MB Flash 100-144pin (mouser.com)
Chapter 40.4.4 : "Note that the maximum frequency for the channel input signal to be
detected correctly is system clock divided by 4, which is required to meet Nyquist criteria
for signal sampling."
So My understanding is the upper limiting frequency should be 60/4 = 15MHz
But base on my testing, captured value become unexpected once the frequency exceed 7MHz ( such as input signal is 8MHz, but calculated frequency is 4MHz base on captured result)
And one more issue is, interrupt cannot be generated once input frequency exceed 10MHz.
No matter 10MHz or 7MHz, they are much different with the document mentioned 15MHz. That makes me quite confused.
the source code has been attached
Please kindly assist, thanks
Thanks & Best Regards
Joshua
