02-29-2012 09:26 AM
Hi,I'm interesting to use clock dividing/multiplication. Use the IP MegaWizard ALTPLL. As i have seen in datasheet, before the MegaWizard function will start work, the asynchronous reset (areset input) have to be done. The Quartus compilation the code was passed, but during ModelSim simulation i got the negative result. The simulation started but automatically stoped (fatal error) the same place where the asynchronous reset for MegaWizard Core was ended. The fatal error message is "floating point exception". I tried to convert: 50Mhz to 10mhz; 50Mhz to 100Mhz; The asynchronous reset I'm making by the counter. what is the reason for the error? Thanks.
02-29-2012 11:31 AM
sorry,it was 10MHz.I have tried to simulate without reset, it's running without any error. But output freq is 'X' value logic...as i said bafore i think it's happens because the ALTPLL modul not locked on my incoming freq... I don't know why... I used the default values of the modul, only the incoming and outcoming freqs were changed.
02-29-2012 11:57 AM
If You're getting X on the output, maybe signal has no initial value? That could be a bug also. Probably nobody would simulate PLL core to get higher frequency in the simulation.
03-01-2012 10:50 AM
Eurika!!!The problem is a result of time definition in ModelSim. I have taken "NanoSeconds" as time definition. But for 50MHz we have to take the "PicoSeconds". In other words, the ALTTTL modul and high entity were working if I was burn it into the FLASH memory of the development board.