https://community.nxp.com/t5/LPC-Microcontrollers/Question-of-external-crystal-oscillator/m-p/1325283#M46190 <P>Hi, Raymond,</P> <P>As you know that the LPC17xx uses internal clock (IRC) after Reset and run application code based on IRC. If your application code switches to external OSC and use external OSC as cclk by either using PLL or not. Once the external OSC stops oscillating, the cpu will stop, all chip will stop, you can not enter interrupt, because there is neither interrupt vector for the external OSC module nor code running.</P> <P><span class="lia-inline-image-display-wrapper lia-image-align-inline" image-alt="xiangjun_rong_0-1629271952126.png" style="width: 400px;"><img src="https://community.nxp.com/t5/image/serverpage/image-id/153309i56E60A0B6CA317FF/image-size/medium?v=v2&amp;px=400" role="button" title="xiangjun_rong_0-1629271952126.png" alt="xiangjun_rong_0-1629271952126.png" /></span></P> <P>&nbsp;</P> <P>Hope it can help you</P> <P>BR</P> <P>XiangJun Rong</P> <P>&nbsp;</P> Wed, 18 Aug 2021 07:33:15 GMT xiangjun_rong 2021-08-18T07:33:15Z https://community.nxp.com/t5/LPC-Microcontrollers/Question-of-external-crystal-oscillator/m-p/1325204#M46188 <P>For LPC17xx:</P><P>外部晶振在失效后能自动切换到内部晶振么？<BR />When external crystal oscillator stop, can LPC17xx switch to internal one?<BR />外部晶振失效能触发错误中断么？<BR />When external crystal oscillator stop, can LPC17xx make a error interrupt?<BR />Thank you!</P> Wed, 18 Aug 2021 06:01:19 GMT https://community.nxp.com/t5/LPC-Microcontrollers/Question-of-external-crystal-oscillator/m-p/1325204#M46188 RaymondX 2021-08-18T06:01:19Z https://community.nxp.com/t5/LPC-Microcontrollers/Question-of-external-crystal-oscillator/m-p/1325283#M46190 <P>Hi, Raymond,</P> <P>As you know that the LPC17xx uses internal clock (IRC) after Reset and run application code based on IRC. If your application code switches to external OSC and use external OSC as cclk by either using PLL or not. Once the external OSC stops oscillating, the cpu will stop, all chip will stop, you can not enter interrupt, because there is neither interrupt vector for the external OSC module nor code running.</P> <P><span class="lia-inline-image-display-wrapper lia-image-align-inline" image-alt="xiangjun_rong_0-1629271952126.png" style="width: 400px;"><img src="https://community.nxp.com/t5/image/serverpage/image-id/153309i56E60A0B6CA317FF/image-size/medium?v=v2&amp;px=400" role="button" title="xiangjun_rong_0-1629271952126.png" alt="xiangjun_rong_0-1629271952126.png" /></span></P> <P>&nbsp;</P> <P>Hope it can help you</P> <P>BR</P> <P>XiangJun Rong</P> <P>&nbsp;</P> Wed, 18 Aug 2021 07:33:15 GMT https://community.nxp.com/t5/LPC-Microcontrollers/Question-of-external-crystal-oscillator/m-p/1325283#M46190 xiangjun_rong 2021-08-18T07:33:15Z