Altera PLL and Altera PLL Dynamic reconfiguration : choose C-counter for two outputs simultaneously.

Question

Good morning,I'm working with Altera PLL/Altera PLL reconfig IP (Cyclone V).The input to Altera PLL is 160 MHz ,the outputs are 125 MHz each with difference of 225 degrees .Then I want to change both outputs to some  another value: for example 120 MHz each. I can change value of M-counters, N-counters and C-Counters accordingly , but how can I choose two C-Counters simultaneously?In addition I've received strange results in the simulation:1). At the first reconfiguration both outputs are 125 MHz.2).At the second reconfiguration first output is 20 MHz (according to M,N,C counters), but second output is 53.333 MHz -despite the fact , that only first counter was chosen.What's happen?

sreekumarr_g_intel · Answer

Did you get chance to do the simulation ? Ideally it shouldn't ..if your setting and counters values are correct..then you should get expected values for the both the output of the PLL.

Thank you ,

Regards,

Sree

agofs · Answer

Good morning,In order to check how Fractional N-PLL reconfiguration works at simulation , I've generated new project .The project consists of PLL, RECONFIG_PLL and incoming/outcoming signals. PLL receives 160 MHz at its input and has only one output .The initial output is 128 MHz, and then changes according to  incoming data.when I've used Fractional N-PLL, then simulation has stuck and stopped after 5000 iterations.when I've used Integer N=PLL, then simulation works properly.The TB is same for both N-PLL.I'm working with ModelSim 10.5 Starter edition.Why simulation of the Fractional N-PLL is sticking?

sreekumarr_g_intel · Answer

Hello, i am not sure  , Can you tell me is that struck /stopped after the Reconfiguration ? anymore hints will help  .Thank you , Regards,Sree

agofs · Answer

Hello,It sticks  at the start of the  Reconfiguration.But I've found some errors at the TB. After repairing these errors, the TB seems working...

sreekumarr_g_intel · Answer

Sure , thank you for the update , can you kindly close the case if there is no further questions ?Thank you , Regards,Sree

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Altera PLL and Altera PLL Dynamic reconfiguration : choose C-counter for two outputs simultaneously.

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