Massimo Ruo Roch

MCF5329 oscillator do not work

Discussion created by Massimo Ruo Roch on Oct 18, 2010
Latest reply on Mar 9, 2011 by Massimo Ruo Roch

Hi all,

I have a problem with a brand new MCF5329 board. I have decidedd to use the internal XTAL oscillator, so I just attached the classical 1 MOhm feedback resistor between XTAL and EXTAL, in parallel to the 16 MHz crystal, and two 15pF capacitors toward ground.

Then I just apply power, keeping the external reset active, and I notice that the oscillator do not work.

The strange thing is that I find 3.3 Volt on both XTAL and EXTAL, while I expect to find opposite polarities, as there is an inverter between the two pins inside tthe CPU.

I have also checked power sequencing, and it works fine, rhaving 3.3 V rising in about 1 ms, followed by 1.5V supply.

Of course the BDM is not working, too.

I have also analyzed system behaviour at poweroff, and I noticed a brief oscillation of the crystal when the power is ramping down.

Any suggestion?

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