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README_testbench.txt
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Advanced Debug Module (adv_dbg_if)
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Nathan Yawn, nathan.yawn@opencores.org
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Three testbenches are supplied with the advanced debug interface. The first
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uses behavioral simulation of a wishbone bus with a memory attached, and
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another behavioral simulation of an OR1200 CPU. This testbench performs
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and tests bus / memory operations, and performs a few CPU operations, The
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top-level module is in adv_dbg_tb.v. Other than the behavioral models, it
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instantiates an adv_dbg_if (found in ../rtl/verilog/), and a JTAG TAP
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("jtag" module, not included with this module). Note that the TAP
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written by Igor Mohor will not work correctly; use the version distributed
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with the Advanced Debug System (written by Nathan Yawn).
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The second testbench includes an actual wishbone/OR1200 system. Its
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top-level entity is xsv_fpga_top. It instantiates a wb_conbus, an OR1200,
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an onchipram, a jtag TAP, and a UART16550, along with an adv_dbg_if. The
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testbench is also instantiated here, and is used to drive the inputs to
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the JTAG TAP. This testbench is less polished, but includes a functional
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test of the single-step capability of the CPU.
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The third testbench is used to test the JTAG serial port function. Its
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top-level entity is adv_dbg_jsp_tb. This testbench instantiates only
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a JTAG TAP and and adv_dbg_if. The CPU module of the adv_dbg_if should
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not be enabled for this testbench. The WB initiator output of the WB
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module is connected point-to-point to the WB target interface of the JTAG
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Serial Port (JSP) module. The WB interface is used to drive the WB side
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of the JSP.
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All testbenches were written for use in ModelSim (version 6.4). A
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wave.do file is also included for each testbench, which will display a
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useful collection of signals in the ModelSim wave view.
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