The tcl command examples below show that the, Commands, Is asserted. the – Altera Virtual JTAG IP Core User Manual
Page 20
four bits long, the minimum length for the VIR value field for all SLD nodes in the design is at least four bits
in length. The Quartus II Tcl API automatically sizes the shift transaction to the correct length. The length
of the VIR register is provided in the Virtual JTAG settings compilation report. If you are driving the JTAG
interface with a custom controller, you must pay attention to size of the
USER1
DR chain.
Figure 10: Equivalent Bit Pattern Shifted into Device by VIR/VDR Shift Commands
Virtual IR Scan
Virtual DR Scan
IR Scan Shift
IR Scan Shift
DR Scan Shift
DR Scan Shift
USER1
USER0
VIR Value
VDR Value
Addr
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
0
0
1
1
1
1
0
Virtual IR/DR Shift Transaction that Captures Current VIR/VDR Values
The Tcl command examples below show that the
no_captured_value
option is not set in the Virtual IR/DR
shift commands and the underlying JTAG shift commands associated with each. In the VIR shift command,
the command returns two
device_dr_shift
commands.
Virtual IR Shift
device_virtual_ir_shift -instance_index 0 -ir_value 1 \
-no_captured_ir_value -show_equivalent_device_ir_dr_shift
Returns:
Info: Equivalent device ir and dr shift commands
Info: device_ir_shift -ir_value 14
Info: device_dr_shift –length 5 –dr_value 0B –value_in_hex
Info: device_dr_shift -length 5 -dr_value 11 -value_in_hex
Virtual DR Shift
device_virtual_dr_shift -instance_index 0 -length 8 -dr_value \
04 -value_in_hex -show_equivalent_device_ir_dr_shift
Returns:
Info: Equivalent device ir and dr shift commands
Info: device_ir_shift -ir_value 12
Info: device_dr_shift -length 8 -dr_value 04 -value_in_hex
The figure below shows an example of VIR/VDR Shift Commands with captured IR values. DR Scan Shift
1 is the
VIR_CAPTURE
command, as shown in the figure below. It targets the VIR of the
sld_hub
. This
command is an address cycle to select the active VIR chain to shift after
jtag_state_cir
is asserted. The
Virtual JTAG Megafunction (sld_virtual_jtag)
Altera Corporation
UG-SLDVRTL
Virtual IR/DR Shift Transaction that Captures Current VIR/VDR Values
20
2014.03.19