Description
Instruction Code
JTAG Instruction
Put the device in JTAG secure mode.
In this mode, only BYPASS, SAMPLE/
PRELOAD
, EXTEST, IDCODE,
SHIFT_EDERROR_REG
, and UNLOCK
instructions are supported. This
instruction can only be accessed
through JTAG core access in user
mode. It cannot be accessed through
external JTAG pins in test or user
mode.
01 1111 0000
LOCK
Release the device from the JTAG
secure mode to enable access to all
other JTAG instructions. This instruc-
tion can only be accessed through
JTAG core access in user mode. It
cannot be accessed through external
JTAG pins in test or user mode.
11 0011 0001
UNLOCK
Clears the volatile key.
00 0010 1001
KEY_CLR_VREG
Verifies the non-volatile key has been
cleared.
00 0001 0011
KEY_VERIFY
If the device is in a reset state and the nCONFIG or nSTATUS signal is low, the device IDCODE might
not be read correctly. To read the device IDCODE correctly, you must issue the IDCODE JTAG
instruction only when the nCONFIG and nSTATUS signals are high.
Note:
Related Information
Provides more information about PULSE_NCONFIG, CONFIG_IO, LOCK, and UNLOCK JTAG instructions.
Provides more information about PULSE_NCONFIG, CONFIG_IO, LOCK, and UNLOCK JTAG instructions.
JTAG Secure Mode
If you enable the tamper-protection bit, the Cyclone V device is in JTAG secure mode after power up. In
the JTAG secure mode, the JTAG pins support only the BYPASS, SAMPLE/PRELOAD, EXTEST, IDCODE,
SHIFT_EDERROR_REG
, and UNLOCK instructions. Issue the UNLOCK JTAG instruction to enable support for
other JTAG instructions.
JTAG Private Instruction
Never invoke the following instruction codes. These instructions can damage and render the
device unusable:
1100010000
Caution:
0011001001
1100010011
JTAG Boundary-Scan Testing in Cyclone V Devices
Altera Corporation
CV-52009
JTAG Secure Mode
9-6
2014.01.10