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Clocks
The HPS-to-FPGA clock interface supplies physical clocks and resets to the FPGA. These clocks and resets
are generated in the HPS.
Alternative Clock Inputs to HPS PLLs
This section lists alternative clock inputs to HPS PLLs.
•
f2h_periph_ref_clock
—FPGA-to-HPS peripheral PLL reference clock. You can connect this
clock input to a clock in your design that is driven by the clock network on the FPGA side.
•
f2h_sdram_ref_clock
—FPGA-to-HPS SDRAM PLL reference clock. You can connect this clock
to a clock in your design that is driven by the clock network on the FPGA side.
User Clocks
A user clock is a PLL output that is connected to the FPGA fabric rather than the HPS. You can connect a
user clock to logic that you instantiate in the FPGA fabric.
•
h2f_user0_clock
—HPS-to-FPGA user clock, driven from main PLL
•
h 2f_user1_clock
—HPS-to-FPGA user clock, driven from peripheral PLL
•
h2f_user2_clock
—HPS-to-FPGA user clock, driven from SDRAM PLL
AXI Bridge FPGA Interface Clocks
The AXI interface has an asynchronous clock crossing in the FPGA-to-HPS bridge. The FPGA-to-HPS and
HPS-to-FPGA interfaces are synchronized to clocksgenerated in the FPGA fabric. These interfaces can be
asynchronous to one another. The SDRAM controller’s multiport front end (MPFE) transfers the data
between the FPGA and HPS clock domains.
•
f2h_axi_clock
—AXI slave clock for FPGA-to-HPS bridge, generated in FPGA fabric
•
h2f_axi_clock
—AXI master clock for HPS-to-FPGA bridge, generated in FPGA fabric
•
h2f_lw_axi_clock
—AXI master clock for lightweight HPS-to-FPGA bridge, generated in FPGA
fabric
SDRAM Clocks
You can configure the HPS component with up to six FPGA-to-HPS SDRAM clocks.
Each command channel to the SDRAM controller has an individual clock source from the FPGA fabric. The
interface clock is always supplied by the FPGA fabric, with clock crossing occurring on the HPS side of the
boundary.
The FPGA-to-HPS SDRAM clocks are driven by soft logic in the FPGA fabric.
•
f2h_sdram0_clock
—SDRAM clock for port 0
•
f2h_sdram1_clock
—SDRAM clock for port 1
•
f2h_sdram2_clock
—SDRAM clock for port 2
•
f2h_sdram3_clock
—SDRAM clock for port 3
•
f2h_sdram4_clock
—SDRAM clock for port 4
•
f2h_sdram5_clock
—SDRAM clock for port 5
Altera Corporation
HPS Component Interfaces
28-5
Clocks
cv_54028
2013.12.30