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Schemascii ± 1

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By dragoncoder047
Tags: electronics programming python

I spent the last two days fooling around with my half-idea of a diagramming program, Schemascii. What it’s supposed to do is be able to make a diagram of a circuit (like the ones you might make in Eagle or KiCad before you plan a circuit board) out of a messy ASCII-art representation.

So far, I have implemented the routines that scan the file first for the components, and second for the connecting wires. The wires are also able to be rendered, but it’s a little buggy.

For testing I have been using this diagram of a 555-timer charge-pump polarity inverter:

*--BAT1+--*-------*---*
|         |       |   |
|         R1    .~~~. |
|         |     :   :-*
|         o-----:   :---+C2--*--D2+--*----------J1
|         |     :U1 :        |       |
|        R2     :555:        |       |
|         |   *-:   :-*      |       |
|         C1  | :   : |      +       C3
|         |   *-:   : C4     D1      +
|         *---* .~~~. |      |       |
|         |       |   |      |       |
*---------*-------*---*------*-------*----------J2

BAT1:5
R1:10k
R2:100k
C1:10000p
C2:10u
C3:100u
C4:10p
D1:1N4001
D2:1N4001
U1:NE555,VCC,DIS,_TR,TH,GND,CTL,OUT,_RST
J1:-5V
J2:GND

So far, my program is able to run around and grab all of the components off the diagram, and also grab the “BOM data” that I placed at the bottom. It ends up in this big dictionary:

{   Cbox(p1=(3+0j), p2=(7+0j), type='BAT', id=1): [   Terminal(pt=(7+0j), flag='+', side=<Side.RIGHT: 1>),
                                                      Terminal(pt=(2+0j), flag=None, side=<Side.LEFT: 3>)],
    Cbox(p1=(16+2j), p2=(21+10j), type='U', id=1): [   Terminal(pt=(21+3j), flag=None, side=<Side.RIGHT: 1>),
                                                       Terminal(pt=(21+4j), flag=None, side=<Side.RIGHT: 1>),
                                                       Terminal(pt=(21+7j), flag=None, side=<Side.RIGHT: 1>),
                                                       Terminal(pt=(18+11j), flag=None, side=<Side.BOTTOM: 2>),
                                                       Terminal(pt=(15+4j), flag=None, side=<Side.LEFT: 3>),
                                                       Terminal(pt=(15+7j), flag=None, side=<Side.LEFT: 3>),
                                                       Terminal(pt=(15+9j), flag=None, side=<Side.LEFT: 3>)],
    Cbox(p1=(10+2j), p2=(12+2j), type='R', id=1): [   Terminal(pt=(10+1j), flag=None, side=<Side.TOP: 0>),
                                                      Terminal(pt=(10+3j), flag=None, side=<Side.BOTTOM: 2>)],
    Cbox(p1=(25+4j), p2=(27+4j), type='C', id=2): [   Terminal(pt=(27+4j), flag=None, side=<Side.RIGHT: 1>),
                                                      Terminal(pt=(24+4j), flag='+', side=<Side.LEFT: 3>)],
    Cbox(p1=(32+4j), p2=(34+4j), type='D', id=2): [   Terminal(pt=(34+4j), flag='+', side=<Side.RIGHT: 1>),
                                                      Terminal(pt=(31+4j), flag=None, side=<Side.LEFT: 3>)],
    Cbox(p1=(48+4j), p2=(50+4j), type='J', id=1): [   Terminal(pt=(47+4j), flag=None, side=<Side.LEFT: 3>)],
    Cbox(p1=(9+6j), p2=(11+6j), type='R', id=2): [   Terminal(pt=(10+5j), flag=None, side=<Side.TOP: 0>),
                                                     Terminal(pt=(10+7j), flag=None, side=<Side.BOTTOM: 2>)],
    Cbox(p1=(10+8j), p2=(12+8j), type='C', id=1): [   Terminal(pt=(10+7j), flag=None, side=<Side.TOP: 0>),
                                                      Terminal(pt=(10+9j), flag=None, side=<Side.BOTTOM: 2>)],
    Cbox(p1=(37+8j), p2=(39+8j), type='C', id=3): [   Terminal(pt=(37+7j), flag=None, side=<Side.TOP: 0>),
                                                      Terminal(pt=(37+9j), flag='+', side=<Side.BOTTOM: 2>)],
    Cbox(p1=(22+9j), p2=(24+9j), type='C', id=4): [   Terminal(pt=(22+8j), flag=None, side=<Side.TOP: 0>),
                                                      Terminal(pt=(22+10j), flag=None, side=<Side.BOTTOM: 2>)],
    Cbox(p1=(29+9j), p2=(31+9j), type='D', id=1): [   Terminal(pt=(29+8j), flag='+', side=<Side.TOP: 0>),
                                                      Terminal(pt=(29+10j), flag=None, side=<Side.BOTTOM: 2>)],
    Cbox(p1=(48+12j), p2=(50+12j), type='J', id=2): [   Terminal(pt=(47+12j), flag=None, side=<Side.LEFT: 3>)]}

Note on the complex numbers

I am (ab)using Python’s complex number as a point or vector, but this kind of makes sense – think the complex plane. The rationale for this is a lot of the mathematical operations I need to do with points are already built-in on complex objects, such as finding the midpoint ((p1 + p2) / 2), finding the length (abs(pt)), finding the angle (cmath.phase(pt)), etc. svgpathtools takes the same approach.

The code for the wire finding is also able to render the wires to SVG, and produces this output on the same circuit:

<g class="wire"><line x1="2.0" y1="0.0" x2="0.0" y2="1.2246467991473532e-16"></line><line x1="0.0" y1="12.0" x2="6.123233995736766e-17" y2="0.0"></line><line x1="10.0" y1="12.0" x2="0.0" y2="12.0"></line><line x1="18.0" y1="12.0" x2="10.0" y2="12.0"></line><line x1="10.0" y1="10.0" x2="10.0" y2="12.0"></line><line x1="22.0" y1="12.0" x2="18.0" y2="12.0"></line><line x1="18.0" y1="11.0" x2="19.0" y2="11.0"></line><line x1="14.0" y1="10.0" x2="10.0" y2="10.0"></line><line x1="10.0" y1="9.0" x2="11.0" y2="9.0"></line><line x1="29.0" y1="12.0" x2="22.0" y2="12.0"></line><line x1="22.0" y1="10.0" x2="22.0" y2="12.0"></line><line x1="14.0" y1="9.0" x2="14.0" y2="11.0"></line><line x1="37.0" y1="12.0" x2="29.0" y2="12.0"></line><line x1="29.0" y1="10.0" x2="29.0" y2="12.0"></line><line x1="15.0" y1="9.0" x2="16.0" y2="9.0"></line><line x1="14.0" y1="7.0" x2="14.0" y2="9.0"></line><line x1="47.0" y1="12.0" x2="37.0" y2="12.0"></line><line x1="37.0" y1="10.0" x2="37.0" y2="12.0"></line><line x1="15.0" y1="7.0" x2="16.0" y2="7.0"></line></g><g class="wire"><line x1="10.0" y1="0.0" x2="10.0" y2="2.0"></line><line x1="18.0" y1="0.0" x2="10.0" y2="1.2246467991473532e-16"></line><line x1="8.0" y1="0.0" x2="10.0" y2="0.0"></line><line x1="22.0" y1="0.0" x2="18.0" y2="1.2246467991473532e-16"></line><line x1="18.0" y1="1.0" x2="19.0" y2="1.0"></line><line x1="22.0" y1="3.0" x2="22.0" y2="0.0"></line><line x1="21.0" y1="3.0" x2="22.0" y2="3.0"></line></g><g class="wire"><line x1="15.0" y1="4.0" x2="10.0" y2="4.0"></line></g><g class="wire"><line x1="23.0" y1="4.0" x2="20.0" y2="4.0"></line></g><g class="wire"><line x1="29.0" y1="4.0" x2="26.0" y2="4.0"></line><line x1="31.0" y1="4.0" x2="29.0" y2="4.0"></line><line x1="29.0" y1="7.0" x2="29.0" y2="4.0"></line></g><g class="wire"><line x1="37.0" y1="4.0" x2="34.0" y2="4.0"></line><line x1="47.0" y1="4.0" x2="37.0" y2="4.0"></line><line x1="37.0" y1="7.0" x2="37.0" y2="4.0"></line></g><g class="wire"><line x1="22.0" y1="7.0" x2="22.0" y2="9.0"></line><line x1="21.0" y1="7.0" x2="22.0" y2="7.0"></line></g>

When put into a <svg> and styled, it reveals a crapload of bugs:

You can mouse over the wires here to see what is connected to what…

…and this reveals the length-2 parts of the wires are getting yanked weirdly to the side, and the length-1 wires aren’t getting rendered at all. This is a cause of great frustration for me, because it doesn’t make sense that it doesn’t render length-1 wires at all. They need to be rendered!

I’m guessing half of the bugs here in my code are caused by stupid off-by-one errors in the search loops, and the rest are just bad algorithms on my part. I really hope I can get these fixed!

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