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Zynq-7000 AP SoC Technical Reference Manual www.xilinx.com 1589
UG585 (v1.11) September 27, 2016
Appendix B: Register Details
Register DDR_PLL_CTRL Details
Relative Address 0x00000104
Absolute Address 0xF8000104
Width 32 bits
Access Type rw
Reset Value 0x0001A008
Description DDR PLL Control
Field Name Bits Type Reset Value Description
reserved 31:19 rw 0x0 Reserved. Writes are ignored, read data is zero.
PLL_FDIV 18:12 rw 0x1A Provide the feedback divisor for the PLL. Note:
Before changing this value, the PLL must first be
bypassed and then put into reset mode. Refer to
the Zynq-7000 TRM, UG585, Clocks chapter for
CP/RES/CNT values for the PLL.
reserved 11:5 rw 0x0 Reserved. Writes are ignored, read data is zero.
PLL_BYPASS_FORCE 4 rw 0x0 DDR PLL Bypass override control:
PLL_BYPASS_QUAL = 0
0: enabled, not bypassed.
1: bypassed.
PLL_BYPASS_QUAL = 1 (QUAL bit default
value)
0: PLL mode is set based on pin strap setting.
1: PLL bypass is enabled regardless of the pin
strapping.
PLL_BYPASS_QUAL 3 rw 0x1 Select the source for the DDR PLL Bypass:
0: controlled by the PLL_BYPASS_FORCE bit.
1: controlled by the value of the sampled
BOOT_MODE pin strapping resistor
PLL_BYPASS. This can be read using the
slcr.BOOT_MODE[4] bit.
reserved 2 rw 0x0 Reserved. Writes are ignored, read data is zero.
PLL_PWRDWN 1 rw 0x0 PLL Power-down control:
0: PLL powered up
1: PLL powered down
PLL_RESET 0 rw 0x0 PLL reset control:
0: de-assert (PLL operating)
1: assert (PLL held in reset)