DDR PHY
The DDR PHY connects the memory controller and external memory devices in the speed critical command
path.
The DDR PHY implements the following functions:
• Calibration—the DDR PHY supports the JEDEC-specified steps to synchronize the memory timing
between the controller and the SDRAM chips. The calibration algorithm is implemented in software.
• Memory device initialization—the DDR PHY performs the mode register write operations to initialize
the devices. The DDR PHY handles re-initialization after a deep power down.
• Single-data-rate to double-data-rate conversion.
Clocks
All clocks are assumed to be asynchronous with respect to the
ddr_dqs_clk
memory clock. All transactions
are synchronized to memory clock domain.
Table 8-7: SDRAM Controller Subsystem Clock Domains
Description
Clock Name
Clock for PHY
ddr_dq_clk
Clock for MPFE, single-port controller, CSR access, and PHY
ddr_dqs_clk
Clock for PHY
ddr_2x_dqs_clk
Clock for CSR interface
l4_sp_clk
Clock for MPU interface
mpu_l2_ram_clk
Clock for L3 interface
l3_main_clk
Six separate clocks used for the FPGA-to-HPS SDRAM ports to the FPGA
fabric
f2h_sdram_
clk[5:0]
In terms of clock relationships, the FPGA fabric connects the appropriate clocks to write data, read data,
and command ports for the constructed ports.
Related Information
on page 2-1
SDRAM Controller Subsystem
Altera Corporation
cv_54008
DDR PHY
8-16
2013.12.30