M52223EVB Relaxation Oscillator

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M52223EVB Relaxation Oscillator

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soccermike
Contributor I
Using the M52223EVB board, I'm trying to use the on-board relaxation oscillator.  When I configure the jumpers, it appears that my on-board oscillator is running at 14MHz.  Additionally, the Coldwarrior Debugger can't modify the ROCR bits TRIM[9:0].  Since the trim is close to the nominal frequency and all the values read back as 0%, this may be the source of the value.  How do I change he ROCR bits?

I also found that CLKSRC functionality doesn't exactly match Figure 5-1. Clock Module Block Diagram.
The diagram shows both the Reference Clock and the PLL come after the Pre-Divider controlled with CCHR.  Instead, I found (and it makes sense) that the Reference Clock comes directly from the CLKMOD0 mux.

Lastly, this diagram should include how OSCSEL affects the clocks.

Thanks in Advance,

Mike
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macl
Senior Contributor I
Hi Mike,
  If the on-board oscillator is 14MHz, then I suspect it is from a small batch of EVBs that went out with initial samples that didn't have the oscillator trimmed correctly.  I recommend returning the board to the distributor (or Freescale, if you bought it direct) and get a new one.  It is not possible to write to the trim bits.
 
On your recommendations for the clock module block diagram, I will forward your suggestions to the documentation team.  Thanks for the feedback. 
 
Mac
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