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

AGofs
Novice
323 Views

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?

 

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6 Replies
SreekumarR_G_Intel
114 Views

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
Novice
114 Views

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
114 Views

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
Novice
114 Views

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
114 Views

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

 

Thank you ,

 

Regards,

Sree

AGofs
Novice
114 Views
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