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Altera_Forum's avatar
Altera_Forum
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10 years ago

Timer Period not correctly

Hi all, my goal is to set a timer with a period time of 1ms and start it. After the time is elapsed it should rise an IRQ (once). The timer itself with interrupt works, but the time is always ab...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
10 years ago

Yes I think it's a problem with the QSys settings. The value you put in the period and snapshot registers are always expressed in clock cycles. This means that if you have a 80MHz clock, you need to write 80000 to get a 1ms timer. The value you write now is too small for a 1ms delay. The period setting that you set in QSys only sets the initial value of the period register. Remember also to enable the "writeable period" option on so that you have the possibility to modify the period register.