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Samo's avatar
Samo
Icon for New Contributor rankNew Contributor
4 months ago

Agilex 5 reconfigurable PLL - emif

Trying to reconfig a PLL with the EMIF Calibration IP

debug via system console

Clocking and PLL User Guide: Agilex™ 5 FPGAs and SoCs

enabled dynamic config within IOPLL and included EMIT Calib.

writing to divide setting addresses -> changes are immediate

multiple pure phase shifts did not work (work randomly)

is there a bit to start the shift

with one design setting N - M - C worked but no multiple shifts

with an other design problems writing to 0x80 to reset pll after setting NMC, no replay

for new nmc setting 6.4.1 enable | 6.4.2 clear calib | 6.4.3 reconfig | 6.4.4 recal

for just phase shifting 6.4.1 read modify write 6.4.3 without 0x80

2.2.12 perform positive or negative phase shift - is there a bit for that? 

Where did I go wrong?

Fpga Devkit

2 Replies

  • Farabi's avatar
    Farabi
    Icon for Regular Contributor rankRegular Contributor
    3 months ago

    Hello,

    Section 2.2.12 explains the PLL phase shift feature.

    Phase shift behavior may depend on:

    1- PLL locked status

    2- Recalibration is triggered or not

    3- EMIF IP is actively using the PLL or not

    Regarding 0x80 reset is not responding- 0x80 is used to reset the PLL, but you need to make sure the PLL is not in used by EMIF or other IPs, and need to make sure PLL is not in locked status.

    Try to follow below sequence :

    1- Enable Reconfig

    2- Clear calibration

    3- Write new settings

    4- Trigger Recalibration

    regards,

    Farabi

    • Samo's avatar
      Samo
      Icon for New Contributor rankNew Contributor
      3 months ago

      Thanks a lot for your reply,

      with your sequence i can shift from 0 to 7 times t_shift (= T_vco/8 ).

      So i can shift 0 or 1 or 2 or .. 7 times t_shift

      My problem is I like to shift for example 20 times t_shift

      Repeating your sequence with 4 times 5 t_shifts does only shift once

      For example only one time 5 t_shift

      If i dont do "4-Trigger Recalib" but insert after each shift a 0-shift

      then it shifts more than the 0..7 range but not continuously (sometimes even changing direction)

      1- enab reconfig

      2- clear calib

      loop

      3a- write phase shift nr>0 (1..7)

      3b- write phase shift nr=0 (0)

      Is this the sequence for multiple shifts?

      And how to perform positive or negativ shift 2.2.12 is there a bit for the direction?