Xilinx ChipScope Pro User Manual

ChipScope Pro Software and Cores User Guide www.xilinx.com 155
UG029 (v14.3) October 16, 2012
CseJtag Tcl Commands
::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 IDCODEs 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: The JTAG target must be locked by using the ::chipscope::csejtag_target lock
subcommand before calling this subcommand.
Syntax
::chipscope::csejtag_tap autodetect_chain handle algorithm
Arguments
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.
%::chipscope::csejtag_tap autodetect_chain $handle
$CSEJTAG_SCAN_DEFAULT
Back to list of all CseJtag Tcl Commands
Table 5-27: Arguments for Subcommand ::chipscope::csejtag_tap
autodetect_chain
Argument Type Description
handle
Required
Handle to the session that is returned by
::chipscope::csejtag_session create.
algorithm Algorithm used to determine the composition of the JTAG
chain. Can be set to one of {$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.

Xilinx ChipScope Pro Specifications

General

Brand	Xilinx
Model	ChipScope Pro
Category	Computer Hardware
Language	English