Specifications
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
• JTAG Secure Mode on page 7-34
Provides more information about PULSE_NCONFIG, CONFIG_IO, LOCK, and UNLOCK JTAG
instructions.
• Configuration, Design Security, and Remote System Upgrades in Cyclone V Devices
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
• 0011001001
• 1100010011
• 1100010111
Caution:
• 0111100000
• 1110110011
• 0011100101
• 0011100110
• 0000101010
• 0000101011
I/O Voltage for JTAG Operation
The Cyclone V device operating in IEEE Std. 1149.1 BST mode uses four dedicated JTAG pins—TDI, TDO,
TMS, and TCK. Cyclone V devices do not support the optional TRST pin.
The TCK pin has an internal weak pull-down resistor, while the TDI and TMS pins have internal weak pull-
up resistors. The 3.3-, 3.0-, or 2.5-V V
CCPD
supply of I/O bank 3A powers the TDO, TDI, TMS, and TCK
pins. All user I/O pins are tri-stated during JTAG configuration.
The JTAG chain supports several different devices. Use the supported TDO and TDI voltage combinations
listed in the following table if the JTAG chain contains devices that have different V
CCIO
levels. The output
voltage level of the TDO pin must meet the specification of the TDI pin it drives.
JTAG Boundary-Scan Testing in Cyclone V Devices
Altera Corporation
Send Feedback
CV-52009
JTAG Secure Mode
9-6
2013.05.06