Zynq-7000 AP SoC and 7 Series FPGAs MIS v4.1
580
UG586 November 30, 2016
Chapter 4:
LPDDR2 SDRAM Memory Interface Solution
app_ref_req
When asserted, this active-High input requests that the Memory Controller send a refresh
command to the DRAM. It must be pulsed for a single cycle to make the request and then
deasserted at least until the
app_ref_ack
signal is asserted to acknowledge the request
and indicate that it has been sent.
app_ref_ack
When asserted, this active-High input acknowledges a refresh request and indicates that
the command has been sent from the Memory Controller to the PHY.
app_zq_req
When asserted, this active-High input requests that the Memory Controller send a ZQ
calibration command to the DRAM. It must be pulsed for a single cycle to make the request
and then deasserted at least until the
app_zq_ack
signal is asserted to acknowledge the
request and indicate that it has been sent.
app_zq_ack
When asserted, this active-High input acknowledges a ZQ calibration request and indicates
that the command has been sent from the Memory Controller to the PHY.
ui_clk_sync_rst
This is the reset output from the UI which is in synchronous with
ui_clk
.
ui_clk
This is the output clock from the UI. It must be half the frequency of the clock going out to
the external SDRAM.
init_calib_complete
The PHY asserts
init_calib_complete
when calibration is finished. The application has
no need to wait for
init_calib_complete
before sending commands to the Memory
Controller.