IEEE Std. 1149.1 BST Operation Control
Figure 14–12. BYPASS Shift Data Register Waveforms
TCK
TMS
Bit 1
Bit 2
Bit 1
Bit 3
Bit 2
TDI
Bit 4
TDO
SHIFT_IR
SHIFT_DR
TAP_STATE
SELECT_DR_SCAN
UPDATE_IR
EXIT1_DR
UPDATE_DR
EXIT1_IR
Data shifted into TDI on
the rising edge of TCK is
shifted out of TDO on the
falling edge of the same
TCK pulse.
CAPTURE_DR
Instruction Code
IDCODE Instruction Mode
The IDCODEinstruction mode is used to identify the devices in an
IEEE Std. 1149.1 chain. When IDCODEis selected, the device
identification register is loaded with the 32-bit vendor-defined
identification code. The device ID register is connected between the TDI
and TDOports, and the device IDCODEis shifted out. The IDCODEfor
Cyclone II devices are listed in the Configuration & Testing chapter in
Volume 1 of the Cyclone II Device Handbook.
USERCODE Instruction Mode
The USERCODEinstruction mode is used to examine the user electronic
signature (UES) within the devices along an IEEE Std. 1149.1 chain. When
this instruction is selected, the device identification register is connected
between the TDIand TDOports. The user-defined UES is shifted into the
device ID register in parallel from the 32-bit USERCODEregister. The UES
is then shifted out through the device ID register. The UES value is not
user defined until after the device has been configured. Before
configuration, the UES value is set to the default value.
CLAMP Instruction Mode
The CLAMPinstruction mode is used to allow the boundary-scan register
to determine the state of the signals driven from the pins. In CLAMP
instruction mode, the bypass register is selected as the serial path
between the TDIand TDOports.
14–14
Altera Corporation
Cyclone II Device Handbook, Volume 1
February 2007
ALTERA [ ALTERA CORPORATION ]
