topic Re: ICS Problem - QE128 in 8-bit Microcontrollers https://community.nxp.com/t5/8-bit-Microcontrollers/ICS-Problem-QE128/m-p/175474#M12190 <HTML><HEAD></HEAD><BODY><DIV></DIV><DIV>Hello Rafael,</DIV><DIV>&nbsp;</DIV><DIV>If you refer to paragraph 3.8 of the datasheet, you will see that the maximum allowable crystal frequency is 16 MHz.&nbsp; However, assuming that FEE mode is used, even if you were to use a&nbsp;25 MHz oscillator with a square wave output, this will not work because none of the RDIV settings available will give a&nbsp;reference frequency between the limits 31.25 to 39.0625 kHz.</DIV><DIV>&nbsp;</DIV><DIV>For example, for a divider value of 512, the input frequency limits would be&nbsp;16 to 20 MHz.&nbsp; For a divider value of 1024, the minimum input frequency would be 32 MHz.</DIV><DIV>&nbsp;</DIV><DIV>Of course it is possible to use FBE mode, but the available bus frequencies would be&nbsp;limited to&nbsp;12.5 MHz, 6.25 MHz, etc.</DIV><DIV>&nbsp;</DIV><DIV>Regards,</DIV><DIV>Mac</DIV><DIV>&nbsp;</DIV><BR /><BR />Message Edited by bigmac on <SPAN class="date_text">2008-07-24</SPAN> <SPAN class="time_text">10:30 AM</SPAN></BODY></HTML> Thu, 24 Jul 2008 07:14:55 GMT bigmac 2008-07-24T07:14:55Z ICS Problem -  QE128 https://community.nxp.com/t5/8-bit-Microcontrollers/ICS-Problem-QE128/m-p/175473#M12189 <HTML><HEAD></HEAD><BODY><DIV> </DIV><P>Hello,<BR />how can I configure an QE128 to have a bus clock of 8Mhz using an 25MHz external XTAL?<BR /><BR />Thanks,<BR />Rafael.</P><P>&nbsp;</P><P>&nbsp;</P><P>&nbsp;</P><P>&nbsp;</P><P>Added p/n to subject.<BR /></P><DIV> </DIV><BR /><BR /><SPAN>Message Edited by NLFSJ on </SPAN><SPAN class="date_text">2008-07-23</SPAN><SPAN> </SPAN><SPAN class="time_text">12:03 PM</SPAN></BODY></HTML> Thu, 24 Jul 2008 01:24:18 GMT https://community.nxp.com/t5/8-bit-Microcontrollers/ICS-Problem-QE128/m-p/175473#M12189 Rafael_21 2008-07-24T01:24:18Z Re: ICS Problem - QE128 https://community.nxp.com/t5/8-bit-Microcontrollers/ICS-Problem-QE128/m-p/175474#M12190 <HTML><HEAD></HEAD><BODY><DIV></DIV><DIV>Hello Rafael,</DIV><DIV>&nbsp;</DIV><DIV>If you refer to paragraph 3.8 of the datasheet, you will see that the maximum allowable crystal frequency is 16 MHz.&nbsp; However, assuming that FEE mode is used, even if you were to use a&nbsp;25 MHz oscillator with a square wave output, this will not work because none of the RDIV settings available will give a&nbsp;reference frequency between the limits 31.25 to 39.0625 kHz.</DIV><DIV>&nbsp;</DIV><DIV>For example, for a divider value of 512, the input frequency limits would be&nbsp;16 to 20 MHz.&nbsp; For a divider value of 1024, the minimum input frequency would be 32 MHz.</DIV><DIV>&nbsp;</DIV><DIV>Of course it is possible to use FBE mode, but the available bus frequencies would be&nbsp;limited to&nbsp;12.5 MHz, 6.25 MHz, etc.</DIV><DIV>&nbsp;</DIV><DIV>Regards,</DIV><DIV>Mac</DIV><DIV>&nbsp;</DIV><BR /><BR />Message Edited by bigmac on <SPAN class="date_text">2008-07-24</SPAN> <SPAN class="time_text">10:30 AM</SPAN></BODY></HTML> Thu, 24 Jul 2008 07:14:55 GMT https://community.nxp.com/t5/8-bit-Microcontrollers/ICS-Problem-QE128/m-p/175474#M12190 bigmac 2008-07-24T07:14:55Z