Clock problem using newer 80Mhz uC8252 card

Andrei Chichak groups at
Thu Oct 22 20:22:01 UTC 2009

In the av5282 BSP start/start.S there is a section of code that sets  
the SYNCR to give 5896000Hz.. In my BSP for Axiom's cml5282, I set  
SYNCR for 64000000Hz.

In the uC5282 BSP, there is no code for setting  SYNCR, so it "should"  
default to XTAL*4. If you have a 16MHz crystal, you get 64000000Hz.  
Perhaps a patch would be prudent so that the processor IS running at  
the expected frequency.


On 2009-October-22, at 1:17 PM, Phillip Sorensen wrote:

> Hello all,
> We have purchased the newer 80Mhz Arcturus Networks uCdimm 5282 (bsp  
> uC5282).  I have added "--defsym _CPUClockSpeed=80000000"
> to linker command line to change the value returned by the  
> bsp_get_CPU_clock_speed() function.  This successfully  changes the  
> settings for the
> serial ports so the console baud rate is correct.  However I  
> discovered that the clock was running fast (about 15 seconds per  
> minute).  Looking at
> the code in the clock/clock.c file in the uC5282 BSP, I discovered  
> that the code assumed that the clock rate was a power of 2, and was  
> using
> the PIT prescaler to count in microseconds.  Since 80 is not a power  
> of two, the calculation was wrong.

Andrei Chichak

Systems Developer
CBF Systems Inc.
4-038 NINT Innovation Centre
11421 Saskatchewan Drive
Edmonton, Alberta
T6G 2M9

Phone: 780-628-2072
Skype: andrei.chichak

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