MCUXpresso General中的主题 frequency detection https://community.nxp.com/t5/MCUXpresso-General/frequency-detection/m-p/707090#M198 <HTML><HEAD></HEAD><BODY><P><SPAN style="color: #333333; background-color: #fcfcfc;">The main chip is k64p144, now want to detect the external input square wave frequency, Through the falling edge of the GPIO pin to capture external interrupt to achieve. If the external square wave frequency is 500 khz, this way can be achieved? Can the system support the work? If not, what is the maximum input frequency for the system? Thank you!</SPAN></P></BODY></HTML> Tue, 19 Sep 2017 02:12:27 GMT lwwl 2017-09-19T02:12:27Z frequency detection https://community.nxp.com/t5/MCUXpresso-General/frequency-detection/m-p/707090#M198 <HTML><HEAD></HEAD><BODY><P><SPAN style="color: #333333; background-color: #fcfcfc;">The main chip is k64p144, now want to detect the external input square wave frequency, Through the falling edge of the GPIO pin to capture external interrupt to achieve. If the external square wave frequency is 500 khz, this way can be achieved? Can the system support the work? If not, what is the maximum input frequency for the system? Thank you!</SPAN></P></BODY></HTML> Tue, 19 Sep 2017 02:12:27 GMT https://community.nxp.com/t5/MCUXpresso-General/frequency-detection/m-p/707090#M198 lwwl 2017-09-19T02:12:27Z Re: frequency detection https://community.nxp.com/t5/MCUXpresso-General/frequency-detection/m-p/707091#M199 <HTML><HEAD></HEAD><BODY><P>Hi&nbsp;l w,</P><P>I recommand you configure FTM module as Dual Edge Capture mode, please read the chapter '40.4.24.4 Period measurement' of <A href="https://www.nxp.com/docs/en/reference-manual/K64P144M120SF5RM.pdf">K64P144M120SF5RM</A>.</P><P><span class="lia-inline-image-display-wrapper" image-alt="Period measurement.png"><img src="https://community.nxp.com/t5/image/serverpage/image-id/30816i5C45D86FC662D1FB/image-size/large?v=v2&amp;px=999" role="button" title="Period measurement.png" alt="Period measurement.png" /></span></P><P>Note that the maximum frequency for the channel input signal to be detected correctly is&nbsp;<STRONG>Bus clock divided by 4</STRONG>, which is required to meet Nyquist criteria for signal sampling.</P><P></P><P>Best Regards,</P><P>Robin</P><P style="min- padding: 0px;">&nbsp;</P><P>-----------------------------------------------------------------------------------------------------------------------<BR />Note: If this post answers your question, please click the Correct Answer button. Thank you!<BR />-----------------------------------------------------------------------------------------------------------------------</P></BODY></HTML> Wed, 20 Sep 2017 07:36:34 GMT https://community.nxp.com/t5/MCUXpresso-General/frequency-detection/m-p/707091#M199 Robin_Shen 2017-09-20T07:36:34Z