Zynq-7000 AP SoC and 7 Series FPGAs MIS v4.1
118
UG586 November 30, 2016
Chapter 1:
DDR3 and DDR2 SDRAM Memory Interface Solution
Native Interface Maintenance Command Signals
lists the native interface maintenance command signals.
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.
Table 1-54:
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.
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.