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Registered: ‎06-11-2017

Zynq Ultrascale+ device PLL not lock

hello, I'am debugging a board of our own manufacture,which use xczu9eg-ffvb1156-2-i.

But we meet very strange problem. Two Important PLLs never lock.

Refer to ug1085, I see the device has several plls


The pll for APU and RPU not locked(as shoiwn below),


xsct% rrd crf_apb pll_status
pll_status: 3a
   vpll_stable (Bits [5]): 1  dpll_stable (Bits [4]): 1
   apll_stable (Bits [3]): 1    vpll_lock (Bits [2]): 0
     dpll_lock (Bits [1]): 1    apll_lock (Bits [0]): 0



and I think this makes all the CPUs held in reset.


xsct% tar
  1  PS TAP
     2  PMU
     3  PL
  4* PSU
     5  RPU (Reset)
        6  Cortex-R5 #0 (RPU Reset)
        7  Cortex-R5 #1 (RPU Reset)
     8  APU (L2 Cache Reset)
        9  Cortex-A53 #0 (APU Reset)
       10  Cortex-A53 #1 (APU Reset)
       11  Cortex-A53 #2 (APU Reset)
       12  Cortex-A53 #3 (APU Reset)

It is strange that the dpll is locked, but apll and vpll does not.



We checked our all power, all are OK.

We checked PS_REF_CLK, it is in right freqency and has good quality.

We checked  PS_POR_B , PS_SRST_B, and find no wrong.


Why the two PLLs not lock ?


How to make the two PLL lock ?

Could anyone do us a favour ?




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1 Reply
Xilinx Employee
Xilinx Employee
Registered: ‎09-01-2014

Re: Zynq Ultrascale+ device PLL not lock

I think you checked in JTAG boot mode. APLL is bypassed or in the reset state.
Please check APLL_CTRL register.
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