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Participant
Participant
10,362 Views
Registered: ‎05-12-2014

Driving AXI Peripherials with External Clock

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Hi,

I have been attempting to drive some AXI peripherals using an external clock, although the design has been tested working with an internal clock (Zynq PLL generated) of the same frequency, it fails to operate when the external clock is used.

 

The ext. clock is fed via a clock enable pin, routed to a MMCM which resets by the Zynq reset output, the locked output from MMCM is connected to corresponding input of the Processor Sys Reset peripheral ensuring the clock is stabilised before peripherals/interconnects are permitted to operate. The AXI clocking interface of the Zynq processor is also driven by the same clock.

 

What have I missed?  :)

 

Thanks,

Ben

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Participant
Participant
19,559 Views
Registered: ‎05-12-2014

Just implemented the design without using the Reset input (MMCM) and confirmed the solution works.

 

Thanks,

Ben

View solution in original post

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Moderator
Moderator
10,322 Views
Registered: ‎07-31-2012

Hi,

 

It looks like  "a MMCM which resets by the Zynq reset output" may not work as the polarity of both are different. Clock conterter IP reset is active low and Zynq PS reset is active high. The connections between them will throw error on IPI block validation.

 

Try to use as shown in screenshot.

 

Regards

P.V

 

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zynq_clock_converter.jpg
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Participant
Participant
10,259 Views
Registered: ‎05-12-2014

Hi P.V.

 

With my configuration, the Reset input of MMCM is actually configured as active low, matches with the output of the reset signal from the PS.  The rest of the arrangement is identical to yours. Perhaps the reset input is not necessary, given the implementation of the dcm locked interface with the Processor Reset Peripheral.  

 

Could you confirm if the illustrated design is functional or is it just aimed for illustration purpose?

 

Thanks,

Ben

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Participant
Participant
19,560 Views
Registered: ‎05-12-2014

Just implemented the design without using the Reset input (MMCM) and confirmed the solution works.

 

Thanks,

Ben

View solution in original post

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