hey guys! i trie to simulate a dcm design with modelsim, but the dcm doesn't start. i tried to reset the dcm after applying clkin, it seems, that the dcm is working, but clkfx is only a amount of spikes instead of a 50:50 clock but at the right frequency. clkin is a 60%:40% clock with 33 MHz. anyone out there with the same problem? thx wolfgang
DCM ISE6.2.3 sim problem
Started by ●July 1, 2004
Reply by ●July 2, 20042004-07-02
Do you have your modelsim resolution set to ps? "wolfgang" <wolfgang.hofmann@arcs.ac.at> wrote in message news:cc14ut$on9$1@newsreader1.utanet.at...> hey guys! > > i trie to simulate a dcm design with modelsim, but the dcm doesn't start.i> tried to reset the dcm after applying clkin, it seems, that the dcm is > working, but clkfx is only a amount of spikes instead of a 50:50 clock but > at the right frequency. clkin is a 60%:40% clock with 33 MHz. > > anyone out there with the same problem? > > thx > > wolfgang > >
Reply by ●July 2, 20042004-07-02
As mentioned, you need your simulator set to ps resolution. Anything coarser can make the model not operate properly. Newer versions of the model warn against this but older ones did not. Also, if you reset the DCM, you must hold the reset for at least 3 full clock cycles. This is a hardware requirement and newer versions of the model again warn you of this. Also check to see if LOCK has gone high. It can take several ns before the DCM LOCKs and before that time, some runt pulses can be seen but after you have achieved LOCK, the DCM is supposed to be operating properly. Also, ensure you have all of the attributes properly set for the DCM as they have an obvious effect on the operation of the model. -- Brian jakab tanko wrote:> Do you have your modelsim resolution set to ps? > "wolfgang" <wolfgang.hofmann@arcs.ac.at> wrote in message > news:cc14ut$on9$1@newsreader1.utanet.at... > >>hey guys! >> >>i trie to simulate a dcm design with modelsim, but the dcm doesn't start. > > i > >>tried to reset the dcm after applying clkin, it seems, that the dcm is >>working, but clkfx is only a amount of spikes instead of a 50:50 clock but >>at the right frequency. clkin is a 60%:40% clock with 33 MHz. >> >>anyone out there with the same problem? >> >>thx >> >>wolfgang >> >> > > >
