Zynq-7000 AP SoC and 7 Series FPGAs MIS v4.1
562
UG586 November 30, 2016
Chapter 4:
LPDDR2 SDRAM Memory Interface Solution
5:
DGEN_WALKING1
. Walking 1s are on the DQ pins. The starting position of
1
depends
on the address value.
6:
DGEN_WALKING0
. Walking 0s are on the DQ pins. The starting position of
0
depends
on the address value.
7:
DGEN_PRBS
. A 32-stage LFSR generates random data and is seeded by the starting
address. This data mode only works with PRBS address mode or Sequential address
mode.
Modifying Port Address Space
The address space for a port can be modified by changing the BEGIN_ADDRESS and
END_ADDRESS parameters found in the top-level test bench file. These two values must be
set to align to the port data width. The two additional parameters, PRBS_SADDR_MASK_POS
and PRBS_EADDR_MASK_POS, are used in the default PRBS address mode to ensure that
out-of-range addresses are not sent to the port. PRBS_SADDR_MASK_POS creates an OR
mask that shifts PRBS-generated addresses with values below BEGIN_ADDRESS up into the
valid address space of the port.
PRBS_SADDR_MASK_POS should be set to a 32-bit value equal to the BEGIN_ADDRESS
parameter. PRBS_EADDR_MASK_POS creates an AND mask that shifts PRBS-generated
addresses with values above END_ADDRESS down into the valid address space of the port.
PRBS_EADDR_MASK_POS should be set to a 32-bit value, where all bits above the
most-significant address bit of END_ADDRESS are set to 1 and all remaining bits are set to
0.
shows some examples of setting the two mask parameters.
Table 4-12:
Example Settings for Address Space and PRBS Masks
SADDR
EADDR PRBS_SADDR_MASK_POS
PRBS_EADDR_MASK_POS
0x1000
0xFFFF
0x00001000
0xFFFF0000
0x2000
0xFFFF
0x00002000
0xFFFF0000
0x3000
0xFFFF
0x00003000
0xFFFF0000
0x4000
0xFFFF
0x00004000
0xFFFF0000
0x5000
0xFFFF
0x00005000
0xFFFF0000
0x2000
0x1FFF
0x00002000 0xFFFFE000
0x2000
0x2FFF
0x00002000 0xFFFFD000
0x2000
0x3FFF
0x00002000 0xFFFFC000
0x2000
0x4FFF
0x00002000 0xFFFF8000
0x2000
0x5FFF
0x00002000 0xFFFF8000
0x2000
0x6FFF
0x00002000 0xFFFF8000
0x2000
0x7FFF
0x00002000 0xFFFF8000
0x2000
0x8FFF
0x00002000 0xFFFF0000
0x2000
0x9FFF
0x00002000 0xFFFF0000