Zynq-7000 AP SoC and 7 Series FPGAs MIS v4.1
584
UG586 November 30, 2016
Chapter 4:
LPDDR2 SDRAM Memory Interface Solution
rd_data
This bus is the data that was read from the external memory. It can be connected to the data
input of a buffer in the user design.
rd_data_addr
This bus is an echo of
data_buf_addr
when the current read request is submitted. This
bus can be combined with the
rd_data_offset
signal and applied to the address input of
a buffer in the user design.
rd_data_en
This signal indicates when valid read data is available on
rd_data
for a read request. It can
be tied to the chip select and write enable of a buffer in the user design.
rd_data_offset
This bus is used to step through the data buffer when the burst length requires more than
a single cycle to complete. This bus can be combined with
rd_data_addr
and applied to
the address input of a buffer in the user design.
Native Interface Maintenance Command Signals
lists the native interface maintenance command signals.
Table 4-19:
Native Interface Read Command Signals
Signal
Direction
Description
rd_data[2
×
nCK_PER_CLK
×
PAYLOAD_WIDTH – 1:0] Output
This is the output data from read
commands.
rd_data_addr[DATA_BUF_ADDR_WIDTH – 1:0]
Output
This output provides the base address of the
destination buffer for read commands.
rd_data_en
Output
This output indicates that valid read data is
available on the rd_data bus.
rd_data_offset[1:0]
Output
This output provides the offset for the
destination buffer for read commands.
Table 4-20:
Native Interface Maintenance Command Signals
Signal
Direction
Description
app_sr_req
Input
This input is reserved and should be tied to 0.
app_sr_active
Output
This output is reserved.
app_ref_req
Input
This active-High input requests that a refresh command be issued to the
DRAM.
app_ref_ack
Output
This active-High output indicates that the Memory Controller has sent the
requested refresh command to the PHY interface.