topic Re: XTALOUT output with 72MHz - LPC1317-64Pin in LPCXpresso IDE

XTALOUT output with 72MHz - LPC1317-64Pin

lpcware — Thu, 16 Jun 2016 01:32:36 GMT

Content originally posted in LPCWare by aamir ali on Wed Dec 12 23:17:02 MST 2012
What should be output of XTALOUT.
I have 72Mhz from internal 12MHz RC oscillator & XTALIN is grounded for noise immunity.

I checked on CRo its varying b/w 5.7Khz - 7.5Khz with 400mv amplitude.
Is it right.

How to determine what will be XTALout output in general when external osc is uesd or when internal oscillator is used.

Re: XTALOUT output with 72MHz - LPC1317-64Pin

lpcware — Thu, 16 Jun 2016 01:32:37 GMT

Content originally posted in LPCWare by Ex-Zero on Wed Dec 12 23:33:00 MST 2012

Quote: Aamir Ali
How to determine what will be XTALout output in general when external osc is uesd or when internal oscillator is used.

Just scope CLKOUT :)

Re: XTALOUT output with 72MHz - LPC1317-64Pin

lpcware — Thu, 16 Jun 2016 01:32:38 GMT

Content originally posted in LPCWare by aamir ali on Thu Dec 13 02:17:49 MST 2012

Quote: Zero
Just scope CLKOUT :)

I think Clkout & XTALOUT are diffrent.
CLKOUT can be configured to set which freq will be at output. & its not like default output will be as same as XTALOUT.

Re: XTALOUT output with 72MHz - LPC1317-64Pin

lpcware — Thu, 16 Jun 2016 01:32:38 GMT

Content originally posted in LPCWare by gbm on Thu Dec 13 02:46:13 MST 2012
XTALOUT is an output of an amplifier for external crystal. It doesn't work unless you connect an external crystal and turn on the oscillator in your firmware.

Re: XTALOUT output with 72MHz - LPC1317-64Pin

lpcware — Thu, 16 Jun 2016 01:32:39 GMT

Content originally posted in LPCWare by aamir ali on Thu Dec 13 04:48:02 MST 2012
1. Then what the output in that case in general for any microcontroller.

Does output when external osc is used is:

Fout = Fosc/machine cycle;

2. If there is no output as you said, why I got reading across it as mentioed in first post.