Chipscope::csejtag_Tap Autodetect_Chain - Xilinx ChipScope Pro User Manual

::chipscope::csejtag_tap autodetect_chain

This subcommand attempts to automatically detect the composition of the JTAG chain.
The subcommand first obtains the number of devices and IDCODE values for devices in the
JTAG chain. The IR lengths are then determined for the devices in the JTAG chain that have
an IDCODE . The IR lengths for devices that do not have corresponding IDCODE s must be
assigned manually. Upon success, all pertinent device information is determined and set in
the session. Some IEEE 1149.1 non-compliant devices might not be compatible with this
subcommand and might cause the entire chain to be detected incorrectly or not at all.
Note:
subcommand before calling this subcommand.
Syntax
Arguments
Table 5-27: Arguments for Subcommand ::chipscope::csejtag_tap
autodetect_chain
Returns
An exception is thrown if the subcommand fails to detect the chain completely. In the case
of such an error, the devices in the JTAG chain must be detected and assigned manually.
Example
Attempt to automatically detect the chain using the default algorithm.
Back to list of all CseJtag Tcl Commands
ChipScope Pro Software and Cores User Guide
UG029 (v14.3) October 16, 2012
The JTAG target must be locked by using the
::chipscope::csejtag_tap autodetect_chain handle algorithm
Argument Type
handle
algorithm
Required
%::chipscope::csejtag_tap autodetect_chain $handle
$CSEJTAG_SCAN_DEFAULT
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::chipscope::csejtag_target lock
Description
Handle to the session that is returned by
::chipscope::csejtag_session create.
Algorithm used to determine the composition of the JTAG
chain. Can be set to one of {$CSEJTAG_SCAN_DEFAULT |
$CSEJTAG_SCAN_TLRSHIFT |
$CSEJTAG_SCAN_WALKING_ONES}
The CSEJTAG_SCAN_WALKING_ONES algorithm is:
• Set each device into BYPASS by shifting long stream of 1's
into IR.
• Shift DR pattern into TDI and wait for pattern on TDO. The
number of shifts determines the number of devices in the
JTAG chain.
• Perform the CSEJTAG_SCAN_TLRSHIFT algorithm to get
IDCODEs for each device.
The CSEJTAG_SCAN_TLRSHIFT algorithm is:
• Navigate to TLR
Shift out bits until all IDCODEs (or BYPASS bits) are read.
CseJtag Tcl Commands
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