8–58 Chapter 8: Configuration and Remote System Upgrades in Cyclone IV Devices
Configuration
Cyclone IV Device Handbook, May 2013 Altera Corporation
Volume 1
Use the
ACTIVE_DISENGAGE
instruction with the
CONFIG_IO
instruction to interrupt
configuration. Table 8–16 lists the sequence of instructions to use for various
CONFIG_IO
usage scenarios.
The
CONFIG_IO
instruction does not hold
nSTATUS
low until reconfiguration. You must
disengage the AS or AP configuration controller by issuing the
ACTIVE_DISENGAGE
and
ACTIVE_ENGAGE
instructions when active configuration is interrupted. You must issue
the
ACTIVE_DISENGAGE
instruction alone or prior to the
CONFIG_IO
instruction if the
JTAG_PROGRAM
instruction is to be issued later (Table 8–17). This puts the active
configuration controllers into the idle state. The active configuration controller is re-
engaged after user mode is reached through JTAG programming (Table 8–17).
1 While executing the
CONFIG_IO
instruction, all user I/Os are tri-stated.
If reconfiguration after interruption is performed using configuration modes (rather
than using
JTAG_PROGRAM
), it is not necessary to issue the
ACTIVE_DISENGAGE
instruction prior to
CONFIG_IO
. You can start reconfiguration by either pulling
nCONFIG
low for at least 500 ns or issuing the
PULSE_NCONFIG
instruction. If the
ACTIVE_DISENGAGE
instruction was issued and the
JTAG_PROGRAM
instruction fails to
enter user mode, you must issue the
ACTIVE_ENGAGE
instruction to reactivate the active
configuration controller. Issuing the
ACTIVE_ENGAGE
instruction also triggers
reconfiguration in configuration modes; therefore, it is not necessary to pull
nCONFIG
low or issue the
PULSE_NCONFIG
instruction.
Table 8–16. JTAG CONFIG_IO (without JTAG_PROGRAM) Instruction Flows
(1)
JTAG Instruction
Configuration Scheme and Current State of the Cyclone IV Device
Prior to User Mode
(Interrupting Configuration)
User Mode Power Up
PS FPP AS AP PS FPP AS AP PS FPP AS AP
ACTIVE_DISENGAGE
O O O 0 O O O 0 ————
CONFIG_IO
R R R R R R R R NA NA NA NA
JTAG Boundary Scan
Instructions (no
JTAG_PROGRAM
)
O O O 0 O O O 0 ————
ACTIVE_ENGAGE
AA
R
(2)
R
(2)
AA
R
(2)
R
(2)
————
PULSE_NCONFIG
A
(3)
A
(3)
O 0 ————
Pulse
nCONFIG
pin A
(3)
A
(3)
O 0 ————
JTAG TAP Reset R R R R R R R R — — — —
Notes to Table 8–16:
(1) You must execute “R” indicates that the instruction before the next instruction, “O” indicates the optional instruction, “A” indicates
that the instruction must be executed, and “NA” indicates that the instruction is not allowed in this mode.
(2) Required if you use
ACTIVE_DISENGAGE
.
(3) Neither of the instruction is required if you use
ACTIVE_ENGAGE
.
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