"ValueError: Cannot parse '470' to resistance" (populate)

[dhaillant]

Hello,
I'm trying to use the res_band feature with populate.
I get this error:

Traceback (most recent call last):
File "/home/david/.local/bin/pcbdraw", line 8, in
sys.exit(run())
File "/home/david/.local/lib/python3.8/site-packages/click/core.py", line 1128, in call
return self.main(*args, **kwargs)
File "/home/david/.local/lib/python3.8/site-packages/click/core.py", line 1053, in main
rv = self.invoke(ctx)
File "/home/david/.local/lib/python3.8/site-packages/click/core.py", line 1659, in invoke
return _process_result(sub_ctx.command.invoke(sub_ctx))
File "/home/david/.local/lib/python3.8/site-packages/click/core.py", line 1395, in invoke
return ctx.invoke(self.callback, **ctx.params)
File "/home/david/.local/lib/python3.8/site-packages/click/core.py", line 754, in invoke
return __callback(*args, **kwargs)
File "/home/david/.local/lib/python3.8/site-packages/pcbdraw/populate.py", line 300, in populate
parsed_content = generate_images(parsed_content, board, prepare_params(header["params"]),
File "/home/david/.local/lib/python3.8/site-packages/pcbdraw/populate.py", line 193, in generate_images
generate_image(boardfilename, x["side"], x["components"],
File "/home/david/.local/lib/python3.8/site-packages/pcbdraw/populate.py", line 212, in generate_image
plot.main(args=plot_args)
File "/home/david/.local/lib/python3.8/site-packages/click/core.py", line 1053, in main
rv = self.invoke(ctx)
File "/home/david/.local/lib/python3.8/site-packages/click/core.py", line 1395, in invoke
return ctx.invoke(self.callback, **ctx.params)
File "/home/david/.local/lib/python3.8/site-packages/click/core.py", line 754, in invoke
return __callback(*args, **kwargs)
File "/home/david/.local/lib/python3.8/site-packages/pcbdraw/ui.py", line 174, in plot
image = plotter.plot()
File "/home/david/.local/lib/python3.8/site-packages/pcbdraw/plot.py", line 1053, in plot
plotter.render(self)
File "/home/david/.local/lib/python3.8/site-packages/pcbdraw/plot.py", line 812, in render
plotter.walk_components(invert_side=False, callback=self._append_component)
File "/home/david/.local/lib/python3.8/site-packages/pcbdraw/plot.py", line 1084, in walk_components
callback(lib, name, ref, value, pos)
File "/home/david/.local/lib/python3.8/site-packages/pcbdraw/plot.py", line 840, in _append_component
ret = self._create_component(lib, name, ref, value)
File "/home/david/.local/lib/python3.8/site-packages/pcbdraw/plot.py", line 890, in _create_component
self._apply_resistor_code(component_element, id_prefix, ref, value)
File "/home/david/.local/lib/python3.8/site-packages/pcbdraw/plot.py", line 912, in _apply_resistor_code
res, tolerance = self._get_resistance_from_value(value)
File "/home/david/.local/lib/python3.8/site-packages/pcbdraw/plot.py", line 947, in _get_resistance_from_value
res = read_resistance(value_l[0])
File "/home/david/.local/lib/python3.8/site-packages/pcbdraw/unit.py", line 39, in read_resistance
raise ValueError(f"Cannot parse '{value}' to resistance")
ValueError: Cannot parse '470' to resistance

If I understand correctly, the value '470' is retrieved from the .kicad_pcb file.
The script parses correctly an other value (100k) and generates correctly the corresponding picture.

Also, in this case I use the default resistor footprint. Not my custom one (see other issue #116 )

Thank you.

[Electro707]

Can confirm this is a bug, and I can pin-point what is the cause of the crash.

[yaqwsx]

That Pcbdraw doesn't accept values without any marking is on purpose - all the schematics that I have ever worked with never used raw numbers to mark the resistance. Therefore, a raw number was considered an error that should be reported to the user, and they should review if there is an error or not.

@dhaillant Do you commonly use "ohm" values without any marking? Is it a common practice? If so, I will be happy to change the behavior.

[Electro707]

@yaqwsx Even with the marking, for example 10Ohm, the function will still raise a ValueError the way it's currently implemented.

[yaqwsx]

10Ohm should be parsed, and that we should fix. At the moment, I am more interested in if 10 should be parsed or not.

[Electro707]

I am of the personal opinion that it should, as most schematic do not bother to add the unit if the symbol is clearly a resistor.

[dhaillant]

Personally, for resistors, I use 470 without unit in my schematics, when there's no confusion possible (when the symbol is clearly a resistor).

I did some quick research and found many different ways among magazines, service manuals, open source schematics etc.
Some use an R, others just numbers. And even, in some schematics, I found both styles (R seems to be added when the values are under 100 Ω)...

Now, I was wondering how the script handles values such as 4k7, 4.7k, 4.7R, 4R7, 0.47, 0R47, 4700k etc?

Thanks!

[Electro707]

As currently implemented and with my fix (PR #118), here how the script handles the numbers you have:

4k7      ->      4007.0
4.7k     ->      4700.0
Failed for 4.7R
Failed for 4R7
0.47     ->      0.47
Failed for 0R47
4700k  ->      4700000.0

[Electro707]

With my recent commit 04c0e01, I was able to get the resistance parsing function to properly parse all the examples you gave:

4k7      ->      4700.0
4.7k     ->      4700.0
4.7R     ->      4.7
4R7      ->      4.7
0.47     ->      0.47
0R47     ->      0.47
4700k    ->      4700000.0

[dhaillant]

Nice!
What about:
470m (0.47)
470M (470000k)
and 4M7

[Electro707]

470m     ->      0.47000000000000003
470M     ->      470000000.0
4M7      ->      4700000.0

[dhaillant]

@Electro707 How could I test your version? Thanks :)

[Electro707]

@dhaillant You can clone my fork of this project and checkout the fix_117 branch:
https://github.com/Electro707/PcbDraw/tree/fix_117

Then you can run pcbdraw directly from the cloned folder by running python -m pcbdraw.ui with the current path being inside the repository.

[dhaillant]

Thank you very much @Electro707 !
However, I get this error when I try either plot or populate commands:

david@b101p02:~/tmp/test/PcbDraw$ python -m pcbdraw.ui populate ~/elec/simple\ vca/1.0/populate.txt ~/elec/simple\ vca/1.0/img/
wx._core.wxAssertionError: C++ assertion "false" failed at /build/kicad-YdG4kW/kicad-6.0.8-0/kicad/common/layer_id.cpp(180) in LayerName(): Unknown layer ID -1

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
File "/usr/lib/python3.8/runpy.py", line 194, in _run_module_as_main
return _run_code(code, main_globals, None,
File "/usr/lib/python3.8/runpy.py", line 87, in _run_code
exec(code, run_globals)
File "/home/david/tmp/test/PcbDraw/pcbdraw/ui.py", line 312, in
run()
File "/home/david/.local/lib/python3.8/site-packages/click/core.py", line 1128, in call
return self.main(*args, **kwargs)
File "/home/david/.local/lib/python3.8/site-packages/click/core.py", line 1053, in main
rv = self.invoke(ctx)
File "/home/david/.local/lib/python3.8/site-packages/click/core.py", line 1659, in invoke
return _process_result(sub_ctx.command.invoke(sub_ctx))
File "/home/david/.local/lib/python3.8/site-packages/click/core.py", line 1395, in invoke
return ctx.invoke(self.callback, **ctx.params)
File "/home/david/.local/lib/python3.8/site-packages/click/core.py", line 754, in invoke
return __callback(*args, **kwargs)
File "/home/david/tmp/test/PcbDraw/pcbdraw/populate.py", line 300, in populate
parsed_content = generate_images(parsed_content, board, prepare_params(header["params"]),
File "/home/david/tmp/test/PcbDraw/pcbdraw/populate.py", line 193, in generate_images
generate_image(boardfilename, x["side"], x["components"],
File "/home/david/tmp/test/PcbDraw/pcbdraw/populate.py", line 212, in generate_image
plot.main(args=plot_args)
File "/home/david/.local/lib/python3.8/site-packages/click/core.py", line 1053, in main
rv = self.invoke(ctx)
File "/home/david/.local/lib/python3.8/site-packages/click/core.py", line 1395, in invoke
return ctx.invoke(self.callback, **ctx.params)
File "/home/david/.local/lib/python3.8/site-packages/click/core.py", line 754, in invoke
return __callback(*args, **kwargs)
File "/home/david/tmp/test/PcbDraw/pcbdraw/ui.py", line 174, in plot
image = plotter.plot()
File "/home/david/tmp/test/PcbDraw/pcbdraw/plot.py", line 1053, in plot
plotter.render(self)
File "/home/david/tmp/test/PcbDraw/pcbdraw/plot.py", line 674, in render
self._plotter.execute_plot_plan(to_plot)
File "/home/david/tmp/test/PcbDraw/pcbdraw/plot.py", line 1207, in execute_plot_plan
pctl.OpenPlotfile(action.name, pcbnew.PLOT_FORMAT_SVG, action.name)
File "/usr/lib/python3/dist-packages/pcbnew.py", line 7586, in OpenPlotfile
return _pcbnew.PLOT_CONTROLLER_OpenPlotfile(self, aSuffix, aFormat, aSheetDesc)
SystemError: returned a result with an error set

I'm not familiar with python, so I have no idea if I'm using it the right way...
(python -m pcbdraw.ui doesn't generate this error)

[yaqwsx]

The reason for that is incompatibility introduced in KiCAD 6.0.8. The current PcbDraw upstream already addresses this, @Electro707's fork, did not.

[Electro707]

@dhaillant Which branch are you on? If you are on master, that would make sense as I haven't updated it in a while.

[dhaillant]

@Electro707 I'm on fix_117
As @yaqwsx said, it was an incompatibility issue introduced in KiCad 6.0.8.