Thread: [myhdl-list] co-simuation

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Hello All,
I am testing VHD2VL and trying to test the outputted file ifchain.v with MyHDL & Iverilog
co-simulation on a Raspberry Pi 2 B.

I created the files and folder vcd 
https://github.com/develone/raspberrypi2_yocto/tree/master/vhd2vl/examples/tb

ifchain  myhdl.vpi  tb_ifchain.v  test_ifchain.py  vcd

The above files were based on Chris Felton alt.hdl
that I had forked and tested on Raspberry Pi 2 B 
https://github.com/develone/alt.hdl/tree/master/examples/ex2_mathadds/test_verilogs
    git clone https://github.com/develone/alt.hdl.git
    cd alt.hdl/examples/ex2_mathadds/test_verilogs/
    cp ~/raspberrypi2_yocto/vhd2vl/examples/tb/myhdl.vpi .
    mkdir vcd
    python test_mathadds.py
This producee the expected output.
The output in next few lines below between the *** are  to verify GTKWAVE, MyHDL & Iverilog 
work with a Co-Simulation on Raspberry Pi 2 B.
*******************************************************************
python test_mathadds.py 
compiling ...
  *iverilog -o mathadds ../myhdl/mm_maths1.v ../bsv/mb_maths1.v ../bsv/mkMaths1.v ../chisel/generated/mc_maths1.v ./tb_mathadds.v 
cosimulation setup ...
VCD info: dumpfile vcd/maths1.vcd opened for output.
start (co)simulation ...
      33:  [       0,        0] mb     0,  mc     0,  mm     0 [20]
      34:  [       1,        1] mb    20,  mc    20,  mm    20 [20]
      35:  [       1,        1] mb    20,  mc    20,  mm    20 [20]
      36:  [       1,        1] mb    20,  mc    20,  mm    20 [20]
      37:  [       1,        1] mb    20,  mc    20,  mm    20 [5300]
      38:  [     543,      -13] mb  5300,  mc  5300,  mm  5300 [5300]
      39:  [     543,      -13] mb  5300,  mc  5300,  mm  5300 [5300]
      40:  [     543,      -13] mb  5300,  mc  5300,  mm  5300 [5300]
      41:  [     543,      -13] mb  5300,  mc  5300,  mm  5300 [-50]
      42:  [      -7,        2] mb   -50,  mc   -50,  mm   -50 [-50]
      43:  [      -7,        2] mb   -50,  mc   -50,  mm   -50 [-50]
      44:  [      -7,        2] mb   -50,  mc   -50,  mm   -50 [-50]
      45:  [      -7,        2] mb   -50,  mc   -50,  mm   -50 [630010]
      46:  [   31000,    32001] mb -25350,  mc -25350,  mm -25350 [630010]
      47:  [   31000,    32001] mb -25350,  mc -25350,  mm -25350 [630010]
      48:  [   31000,    32001] mb -25350,  mc -25350,  mm -25350 [630010]
In addition the gtkwave vcd/maths1.vcd shows the expected signal changes
*******************************************************************

If in stimlus section of test_ifchain.py.
I comment the lines 25 & 26 I get the results below.

    python test_ifchain.py
    Running test...
     0
      *{'a': Signal(intbv(0L)), 'status': Signal(False), 'b': Signal(intbv(0L)),
    compiling ...
      iverilog -o ifchain ../ifchain.v ./tb_ifchain.v
    cosimulation setup ...
      vvp -m ./myhdl.vpi ifchain
    VCD info: dumpfile vcd/ifchain1.vcd opened for output.
      <myhdl._Cosimulation.Cosimulation object at 0x769f6870>
    back from prep cosim
    start (co)simulation ...

This appears to work okay but when I gtkwave vcd/ifchain1.vcd
The signals a,b and clk red and status is yellow.

When the I uncomment lines 25 & 26 try send values to the co-simulation.
The program does not run to completion but crashes with the following error.
  File "/usr/lib/python2.7/site-packages/myhdl-1.0dev-py2.7.egg/myhdl/_Waiter.py", line 142, in next
    clause = next(self.generator)
  File "test_ifchain.py", line 25, in stimlus
    a.next = 10

Not be an experienced co-simulation user I asked if anyone can provide me insight into this
problem.  Thanks in advance. Edward Vidal Jr. e-mail dev...@sb... 915-595-1613