Michael Pollack

M52223EVB Relaxation Oscillator

Discussion created by Michael Pollack on Jun 14, 2007
Latest reply on Jun 15, 2007 by Maclain Lobdell
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,