Best way to determine tb_ticks_per_jiffy inside todc_calibrate_decr()
ktdann at gmail.com
Fri Apr 8 18:45:22 EST 2005
I seem to have problem getting 1 second right. Board has no RTC so
I've basically NULLed all the todc_XXX functions except
Now question is, what value should I be assigning it to tb_ticks_per_jiffy ?
I was able to dig up some info from the archive, and it read,
=-=-=-FROM ARCHIVE =-=-=-
You must find this value by yourself but a good starting point is your
frequency in Hz (I think)
Example of the code
unsigned int freq = 28000000;
tb_tick_per_jiffy = freq/HZ;
tb_to_us = mulhwu_scale_factor(freq,1000000);
=-=-=-END OF ARCHIVE =-=-=-
I'm fine with working it out myself but where do I start ? My board
has 33MHz OSC, so I've trie freq = 33 * 1000000 (where HZ is defined
100) but it turned out to be little short. I could have just tried few
more trial and error, but I prefer knowing what I'm doing so.. :)
Before I was trying it with 100 * 1000000 which had delays like 10:1.
Now its only about 1.5:1. So, I guess I'm on the right track.... so
can anyone please help me out here?
Also, could anyone spill their brain on mulhwu_scale_factor() ? I've
followed the code and ended up reading what seems to be a assembler.
(Should have paid attention during the lectures :P) Any hint on this ?
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