Clock problem using newer 80Mhz uC8252 card
groups at chichak.ca
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
> the PIT prescaler to count in microseconds. Since 80 is not a power
> of two, the calculation was wrong.
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