Nigel Lawrence

Problem: Reset causes MC9S12E128 crystal to stop!

Discussion created by Nigel Lawrence on Jan 30, 2006
Latest reply on Jan 31, 2006 by Nigel Lawrence
Hi, I would appreciate it if anyone could suggest a cause for the following unusual problem.
 
I have a board with an MC9S12E128 80-pin processor on it and the crystal starts up properly every time I power up the board (i.e. cold boot).  However, if I ever activate the reset line (warm boot) this always causes the crystal to stop oscillating and the processor continues operating from its internal oscillator.
 
I have replaced the microprocessor, tried various crystal manufacturers and verified the PLL components, all without success...  The only remaining issue that I can think of is the layout of the PCB.  I am using a 4-layer PCB with a solid ground plane and I do not have any "noisy" supplies or traces routed anywhere near the crystal or PLL filter components.
 
I am using a 3.6864MHz crystal, PLL set to boost speed to 11.0592MHz, I have a 4k7 pull-up resistor on the /RESET line and my VCC is 3.3V.
 
Regards, NigelL

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