topic USB min frequency in Kinetis Microcontrollers https://community.nxp.com/t5/Kinetis-Microcontrollers/USB-min-frequency/m-p/372162#M19382 <HTML><HEAD></HEAD><BODY><P>Hello,</P><P>what's the min CPU frequency Freesscale bare metal USB stack (namely generic HID device) can reliably run on KL26?</P><P>I clock USB module 48 MHz.</P><P></P><P>When I compile my C code without optimization and CPU runs on 12 MHz I mainly get "USB device not recognized" error in Windows when I connect my device to PC (90% probability I will get the error)</P><P></P><P>No optimization and 24 Mhz CPU leads to "USB device cannot start, Code 10" in Windows (10 % probabality I will get the error)</P><P></P><P>Optimization and 12 MHz CPU leads to "USB device cannot start, Code 10" in Windows (10 % probabality I will get the error)</P><P></P><P>Optimization and 24 Mhz leads to no error.</P></BODY></HTML> Tue, 16 Sep 2014 14:56:42 GMT martindusek 2014-09-16T14:56:42Z USB min frequency https://community.nxp.com/t5/Kinetis-Microcontrollers/USB-min-frequency/m-p/372162#M19382 <HTML><HEAD></HEAD><BODY><P>Hello,</P><P>what's the min CPU frequency Freesscale bare metal USB stack (namely generic HID device) can reliably run on KL26?</P><P>I clock USB module 48 MHz.</P><P></P><P>When I compile my C code without optimization and CPU runs on 12 MHz I mainly get "USB device not recognized" error in Windows when I connect my device to PC (90% probability I will get the error)</P><P></P><P>No optimization and 24 Mhz CPU leads to "USB device cannot start, Code 10" in Windows (10 % probabality I will get the error)</P><P></P><P>Optimization and 12 MHz CPU leads to "USB device cannot start, Code 10" in Windows (10 % probabality I will get the error)</P><P></P><P>Optimization and 24 Mhz leads to no error.</P></BODY></HTML> Tue, 16 Sep 2014 14:56:42 GMT https://community.nxp.com/t5/Kinetis-Microcontrollers/USB-min-frequency/m-p/372162#M19382 martindusek 2014-09-16T14:56:42Z Re: USB min frequency https://community.nxp.com/t5/Kinetis-Microcontrollers/USB-min-frequency/m-p/372163#M19383 <HTML><HEAD></HEAD><BODY><P>Hi</P><P></P><P><span class="lia-inline-image-display-wrapper" image-alt="pastedImage_0.png"><img src="https://community.nxp.com/t5/image/serverpage/image-id/45981i9D36892AFD167623/image-size/large?v=v2&amp;px=999" role="button" title="pastedImage_0.png" alt="pastedImage_0.png" /></span></P><P></P><P>When I run the uTasker USB-HID mouse on the FRDM-KL26Z I can set the system clock to 24MHz and the Flash/Bus clocks to 3MHz and build with GCC with no optimisation and it operates normally (connected &gt;20 times without any errors). Generally there shouldn't be much time critical with the enumeration process.</P><P></P><P>Regards</P><P></P><P>Mark</P></BODY></HTML> Wed, 17 Sep 2014 00:24:09 GMT https://community.nxp.com/t5/Kinetis-Microcontrollers/USB-min-frequency/m-p/372163#M19383 mjbcswitzerland 2014-09-17T00:24:09Z