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Guidelines for IEEE Std. 1149.1 Boundary-Scan Testing
Consider the following guidelines when you perform BST with IEEE Std. 1149.1 devices:
• If the “10...” pattern does not shift out of the instruction register through the
TDO
pin during the first
clock cycle of the
SHIFT_IR
state, the TAP controller did not reach the proper state. To solve this problem,
try one of the following procedures:
• Verify that the TAP controller has reached the
SHIFT_IR
state correctly. To advance the TAP controller
to the
SHIFT_IR
state, return to the
RESET
state and send the
01100
code to the
TMS
pin.
• Check the connections to the
VCC
,
GND
,
JTAG
, and dedicated configuration pins on the device.
• Perform a
SAMPLE/PRELOAD
test cycle before the first
EXTEST
test cycle to ensure that known data is
present at the device pins when you enter
EXTEST
mode. If the
OEJ
update register contains 0, the data
in the
OUTJ
update register is driven out. The state must be known and correct to avoid contention with
other devices in the system.
• Do not perform
EXTEST
testing during in-circuit reconfiguration because
EXTEST
is not supported during
in-circuit reconfiguration. To perform testing, wait for the configuration to complete or issue the
CONFIG_IO
instruction to interrupt configuration.
• After configuration, you cannot test any pins in a differential pin pair. To perform BST after configuration,
edit and redefine the BSC group that correspond to these differential pin pairs as an internal cell.
Related Information
Provides more information about BSC group definitions.
IEEE Std. 1149.1 Boundary-Scan Register
The boundary-scan register is a large serial shift register that uses the
TDI
pin as an input and the
TDO
pin
as an output. The boundary-scan register consists of 3-bit peripheral elements that are associated with
Cyclone V I/O pins. You can use the boundary-scan register to test external pin connections or to capture
internal data.
Altera Corporation
JTAG Boundary-Scan Testing in Cyclone V Devices
9-9
Guidelines for IEEE Std. 1149.1 Boundary-Scan Testing
CV-52009
2014.01.10