Xilinx Zynq-7000 - User Interface

Zynq-7000 AP SoC and 7 Series FPGAs MIS v4.1 577
UG586 November 30, 2016
www.xilinx.com
Chapter 4: LPDDR2 SDRAM Memory Interface Solution
User Interface
The UI is shown in Table 4-14 and connects to an FPGA user design to allow access to an
external memory device.
Table 4-14: User Interface
Signal Direction Description
app_addr[ADDR_WIDTH – 1:0] Input This input indicates the address for the current request.
app_cmd[2:0] Input This input selects the command for the current request.
app_en Input
This is the active-High strobe for the app_addr[], app_cmd[2:0],
and app_hi_pri inputs.
app_rdy Output
This output indicates that the UI is ready to accept commands.
If the signal is deasserted when app_en is enabled, the current
app_cmd and app_addr must be retried until app_rdy is
asserted.
app_hi_pri Input
This active-High input elevates the priority of the current
request.
app_rd_data
[APP_DATA_WIDTH – 1:0]
Output This provides the output data from read commands.
app_rd_data_end Output
This active-High output indicates that the current clock cycle is
the last cycle of output data on app_rd_data[].
app_rd_data_valid Output This active-High output indicates that app_rd_data[] is valid.
app_wdf_data
[APP_DATA_WIDTH – 1:0]
Input This provides the data for write commands.
app_wdf_end Input
This active-High input indicates that the current clock cycle is
the last cycle of input data on app_wdf_data[].
app_wdf_mask
[APP_MASK_WIDTH – 1:0]
Input This provides the mask for app_wdf_data[].
app_wdf_rdy Output
This output indicates that the write data FIFO is ready to receive
data. Write data is accepted when app_wdf_rdy = 1’b1 and
app_wdf_wren = 1’b1.
app_wdf_wren Input This is the active-High strobe for app_wdf_data[].
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.
app_zq_req Input
This active-High input requests that a ZQ calibration command
be issued to the DRAM.
app_zq_ack Output
This active-High output indicates that the Memory Controller
has sent the requested ZQ calibration command to the PHY
interface.
ui_clk Output This UI clock must be a half or quarter of the DRAM clock.
init_calib_complete Output PHY asserts init_calib_complete when calibration is finished.
ui_clk_sync_rst Output This is the active-High UI reset.
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