GHDL Tutorial

1. GHDL Tutorial From http://mbmn.net/uer/tutorials/vhdl-with-ghdl/

2. Makefile # vhdl files FILES = src/* VHDLEX = .vhd # testbench TESTBENCHPATH = testbench/${TESTBENCH}$(VHDLEX) #GHDL CONFIG GHDL_CMD = ghdl GHDL_FLAGS = --ieee=synopsys --warn-no-vital-generic SIMDIR = simulation # Simulation break condition #GHDL_SIM_OPT = --assert-level=error GHDL_SIM_OPT = --stop-time=500ns WAVEFORM_VIEWER = gtkwave all: compile run view new : echo "Setting up project ${PROJECT}" mkdirsrctestbench simulation compile : ifeq ($(strip $(TESTBENCH)),) @echo "TESTBENCH not set. Use TESTBENCH=value to set it." @exit 2 endif mkdir -p simulation $(GHDL_CMD) -i $(GHDL_FLAGS) --workdir=simulation --work=work $(TESTBENCHPATH) $(FILES) $(GHDL_CMD) -m $(GHDL_FLAGS) --workdir=simulation --work=work $(TESTBENCH) @mv $(TESTBENCH) simulation/$(TESTBENCH) run : @$(SIMDIR)/$(TESTBENCH) $(GHDL_SIM_OPT) --vcdgz=$(SIMDIR)/$(TESTBENCH).vcdgz view : gunzip --stdout $(SIMDIR)/$(TESTBENCH).vcdgz | $(WAVEFORM_VIEWER) --vcd clean : $(GHDL_CMD) --clean --workdir=simulation

3. Source: src/and_2.vhd library ieee; use ieee.std_logic_1164.all; use ieee.std_logic_unsigned.all; entity and_2 is port ( a, b : in std_logic; c : out std_logic ); end entity; architecture behav of and_2 is begin c <= a and b; end behav;

4. Testbench: testbench/and_2_tb.vhd library ieee; use ieee.std_logic_1164.all; use ieee.std_logic_unsigned.all; entity and_2_tb is end entity; architecture TB of and_2_tb is component and_2 port( a, b: in std_logic; c : out std_logic); end component; signal sa, sb, sc: std_logic; begin a : and_2 port map(a => sa, b => sb, c => sc); sa <= '0' after 0 ns, '1' after 30 ns, '0' after 60 ns, '1' after 90 ns; sb <= '0' after 0 ns, '1' after 15 ns, '0' after 30 ns, '1' after 45 ns, '0' after 60 ns, '1' after 75 ns, '0' after 90 ns; end TB;

5. Usage • make TESTBENCH=and_2_tb