If
DCLK
is selected as the clock source, software uses the
DCLK
count (
dclkcnt
) register to drive
DCLK
pulses to the FPGA. Writing to the
cnt
field of the
dclkcnt
register triggers the FPGA manager to generate
the specified number of
DCLK
pulses. When all of the
DCLK
pulses have been sent, the
dcntdone
bit of
the
DCLK
status (
dclkstat
) register is set to 1. Software polls the
dcntdone
bit to know when all of the
DCLK
pulses have been sent.
Before another write to the
dclkcnt
register, software needs to write a value of 1 to the
dcntdone
bit to clear the done state.
Note:
The FPGA user I/O pins are still tri-stated in this phase. When the initialization phase completes, the FPGA
releases the optional
INIT_DONE
pin and an external resistor pulls the pin high.
User Mode
The FPGA enters the user mode after exiting the initialization phase. The FPGA user I/O pins are no longer
tri-stated in this phase and the configured soft logic in the FPGA becomes active.
The FPGA remains in user mode until the
nCONFIG
pin is driven low. If the
nCONFIG
pin is driven low,
the FPGA reenters the reset phase. The internal oscillator is disabled in user mode, but is enabled as soon
as the
nCONFIG
pin is driven low.
Related Information
•
Configuration, Design Security, and Remote System Upgrades
For more information about configuring the FPGA through the HPS, refer to the
Configuration, Design
Security, and Remote System Upgrade
appendix in the Cyclone V Device Handbook, Volume 1.
•
For more information about configuring the FPGA through the HPS, refer to the
Booting and Configuration
appendix in the Cyclone V Device Handbook, Volume 3.
•
Booting and Configuration Introduction
on page 30-1
For more information about configuring the FPGA through the HPS, refer to the
Booting and Configuration
appendix.
Clock
The FPGA manager has two clock input signals which are asynchronous to each other. The clock manager
generates these two clocks:
•
cfg_clk
—the configuration slave interface clock input and also the
DCLK
output reference for FPGA
configuration. Enable this clock in the clock manager only when configuration is active or when the
configuration slave interface needs to respond to master requests.
•
l4_mp_clk
—the register slave interface clock.
Related Information
on page 2-1
Altera Corporation
FPGA Manager
13-7
User Mode
cv_54013
2013.12.30