Altera Virtual JTAG IP Core - Manual (Page 39)

Figure 19: Read Side Logic for DCFIFO Design Example
IR Decode/State
Decode Logic
IR_register
State
Information
TDO
TDO
Write_req
Data[7:0]
Write_clock
Read_req
Read_clock
Q[7:0]
Rd_empty
Data_out
VJI Instance
Virtual DR
(Push_out)
SignalTap II
Embedded Logic
Analyzer
Runtime Communication
The Tcl script,
dc_fifo_vji.tcl
, contains three procedures, each corresponding to one of the virtual JTAG
instructions. The table below describes each of the procedures.
Table 17: Run-Time Communication Tcl Procedures
Description Procedure
IR shift the PUSH instruction, followed by a DR shift of the value
argument. Value must be an integer less than 256. push [value]
IR shift the POP instruction, followed by a DR shift of 8 bits. pop
IR shift the FLUSH instruction. flushfifo
The figure below shows runtime execution of eight values pushed into the DCFIFO and a
flushfifo
command, and a SignalTap II Logic Analyzer capture triggering on a flush operation.
Altera Corporation Virtual JTAG Megafunction (sld_virtual_jtag)
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39 Runtime Communication
UG-SLDVRTL
2014.03.19