diff options
| -rw-r--r-- | twisted_coil_gen_twolayer.py | 329 |
1 files changed, 255 insertions, 74 deletions
diff --git a/twisted_coil_gen_twolayer.py b/twisted_coil_gen_twolayer.py index 574b8b8..a4bb653 100644 --- a/twisted_coil_gen_twolayer.py +++ b/twisted_coil_gen_twolayer.py @@ -7,6 +7,7 @@ from math import * from pathlib import Path from itertools import cycle from scipy.constants import mu_0 +import matplotlib as mpl from gerbonara.cad.kicad import pcb as kicad_pcb from gerbonara.cad.kicad import footprints as kicad_fp @@ -87,59 +88,161 @@ def svg_file(fn, stuff, vbw, vbh, vbx=0, vby=0): f.write('</svg>\n') + +# https://en.wikipedia.org/wiki/Farey_sequence#Next_term +def farey_sequence(n: int, descending: bool = False) -> None: + """Print the n'th Farey sequence. Allow for either ascending or descending.""" + a, b, c, d = 0, 1, 1, n + if descending: + a, c = 1, n - 1 + #print(f"{a}/{b}") + yield a, b + + while c <= n and not descending or a > 0 and descending: + k = (n + b) // d + a, b, c, d = c, d, k * c - a, k * d - b + #print(f"{a}/{b}") + yield a, b + + +def divisors(n, max_b=10): + for a, b in farey_sequence(n): + if a == n and b < max_b: + yield b + if b == n and a < max_b: + yield a + + +def print_valid_twists(ctx, param, value): + if not value or ctx.resilient_parsing: + return + + print(f'Valid twist counts for {value} turns:', file=sys.stderr) + for d in divisors(value, value): + print(f' {d}', file=sys.stderr) + + click.echo() + ctx.exit() + + @click.command() @click.argument('outfile', required=False, type=click.Path(writable=True, dir_okay=False, path_type=Path)) @click.option('--footprint-name', help="Name for the generated footprint. Default: Output file name sans extension.") -@click.option('--target-layers', default='F.Cu,B.Cu', help="Target KiCad layers for the generated footprint. Default: F.Cu,B.Cu.") +@click.option('--layer-pair', default='F.Cu,B.Cu', help="Target KiCad layer pair for the generated footprint, comma-separated. Default: F.Cu/B.Cu.") @click.option('--turns', type=int, default=5, help='Number of turns') -@click.option('--diameter', type=float, default=50, help='Outer diameter [mm]') -@click.option('--trace-width', type=float, default=0.15) +@click.option('--outer-diameter', type=float, default=50, help='Outer diameter [mm]') +@click.option('--inner-diameter', type=float, default=25, help='Inner diameter [mm]') +@click.option('--trace-width', type=float, default=None) @click.option('--via-diameter', type=float, default=0.6) @click.option('--via-drill', type=float, default=0.3) +@click.option('--via-offset', type=float, default=None, help='Radially offset vias from trace endpoints [mm]') @click.option('--keepout-zone/--no-keepout-zone', default=True, help='Add a keepout are to the footprint (default: yes)') @click.option('--keepout-margin', type=float, default=5, help='Margin between outside of coil and keepout area (mm, default: 5)') -@click.option('--num-twists', type=int, default=1, help='Number of twists per revolution (default: 1)') -@click.option('--clearance', type=float, default=0.15) +@click.option('--twists', type=int, default=1, help='Number of twists per revolution. Note that this number must be co-prime to the number of turns. Run with --show-twists to list valid values. (default: 1)') +@click.option('--show-twists', callback=print_valid_twists, expose_value=False, type=int, is_eager=True, help='Calculate and show valid --twists counts for the given number of turns. Takes the number of turns as a value.') +@click.option('--clearance', type=float, default=None) +@click.option('--arc-tolerance', type=float, default=0.02) @click.option('--clipboard/--no-clipboard', help='Use clipboard integration (requires wl-clipboard)') @click.option('--counter-clockwise/--clockwise', help='Direction of generated spiral. Default: clockwise when wound from the inside.') -def generate(outfile, turns, diameter, via_diameter, via_drill, trace_width, clearance, footprint_name, target_layers, - num_twists, clipboard, counter_clockwise, keepout_zone, keepout_margin): +@click.version_option() +def generate(outfile, turns, outer_diameter, inner_diameter, via_diameter, via_drill, via_offset, trace_width, clearance, + footprint_name, layer_pair, twists, clipboard, counter_clockwise, keepout_zone, keepout_margin, + arc_tolerance): if 'WAYLAND_DISPLAY' in os.environ: copy, paste, cliputil = ['wl-copy'], ['wl-paste'], 'xclip' else: copy, paste, cliputil = ['xclip', '-i', '-sel', 'clipboard'], ['xclip', '-o', '-sel' 'clipboard'], 'wl-clipboard' + if gcd(twists, turns) != 1: + raise click.ClickException('For the geometry to work out, the --twists parameter must be co-prime to --turns, i.e. the two must have 1 as their greatest common divisor. You can print valid values for --twists by running this command with --show-twists [turns number].') + + outer_radius = outer_diameter/2 + inner_radius = inner_diameter/2 + turns_per_layer = turns/2 + + sweeping_angle = 2*pi * turns_per_layer / twists + spiral_pitch = (outer_radius-inner_radius) / turns_per_layer + c1 = inner_radius + c2 = inner_radius + spiral_pitch + alpha1 = atan((outer_radius - inner_radius) / sweeping_angle / c1) + alpha2 = atan((outer_radius - inner_radius) / sweeping_angle / c2) + alpha = (alpha1+alpha2)/2 + projected_spiral_pitch = spiral_pitch*cos(alpha) + + if trace_width is None and clearance is None: + trace_width = 0.15 + print(f'Warning: Defaulting to {trace_width:.2f} mm trace width.', file=sys.stderr) + + if trace_width is None: + if clearance > projected_spiral_pitch: + raise click.ClickException(f'Error: Given clearance of {clearance:.2f} mm is larger than the projected spiral pitch of {projected_spiral_pitch:.2f} mm. Reduce clearance or increase the size of the coil.') + trace_width = projected_spiral_pitch - clearance + print(f'Calculated trace width for {clearance:.2f} mm clearance is {trace_width:.2f} mm.', file=sys.stderr) + + elif clearance is None: + if trace_width > projected_spiral_pitch: + raise click.ClickException(f'Error: Given trace width of {trace_width:.2f} mm is larger than the projected spiral pitch of {projected_spiral_pitch:.2f} mm. Reduce clearance or increase the size of the coil.') + clearance = projected_spiral_pitch - trace_width + print(f'Calculated clearance for {trace_width:.2f} mm trace width is {clearance:.2f} mm.', file=sys.stderr) + + else: + if trace_width > projected_spiral_pitch: + raise click.ClickException(f'Error: Given trace width of {trace_width:.2f} mm is larger than the projected spiral pitch of {projected_spiral_pitch:.2f} mm. Reduce clearance or increase the size of the coil.') + clearance_actual = projected_spiral_pitch - trace_width + if clearance_actual < clearance: + raise click.ClickException(f'Error: Actual clearance for {trace_width:.2f} mm trace is {clearance_actual:.2f} mm, which is lower than the given clearance of {clearance:.2f} mm.') + + if via_diameter < trace_width: + print(f'Clipping via diameter from {via_diameter:.2f} mm to trace width of {trace_width:.2f} mm.', file=sys.stderr) + via_diameter = trace_width + + inner_via_ring_radius = inner_radius - via_offset + print(f'{inner_radius=} {via_offset=} {via_diameter=}', file=sys.stderr) + inner_via_angle = 2*asin((via_diameter + clearance)/2 / inner_via_ring_radius) + + outer_via_ring_radius = outer_radius + via_offset + outer_via_angle = 2*asin((via_diameter + clearance)/2 / outer_via_ring_radius) + + print(f'Inner via ring @ {inner_via_ring_radius:.2f} mm (from {inner_radius:.2f} mm)', file=sys.stderr) + print(f' {degrees(inner_via_angle):.1f} deg / via', file=sys.stderr) + print(f'Outer via ring @ {outer_via_ring_radius:.2f} mm (from {outer_radius:.2f} mm)', file=sys.stderr) + print(f' {degrees(outer_via_angle):.1f} deg / via', file=sys.stderr) + + if inner_via_angle*twists > 2*pi: + min_dia = 2*((via_diameter + clearance) / (2*sin(pi / twists)) + via_offset) + raise click.ClickException(f'Error: Overlapping vias in inner via ring. Calculated minimum inner diameter is {min_dia:.2f} mm.') pitch = clearance + trace_width - target_layers = [name.strip() for name in target_layers.split(',')] - via_diameter = max(trace_width, via_diameter) + t, _, b = layer_pair.partition(',') + layer_pair = (t.strip(), b.strip()) rainbow = '#817 #a35 #c66 #e94 #ed0 #9d5 #4d8 #2cb #0bc #09c #36b #639'.split() rainbow = rainbow[2::3] + rainbow[1::3] + rainbow[0::3] - out_paths = [SVGPath(fill='none', stroke=rainbow[i%len(rainbow)], stroke_width=trace_width, stroke_linejoin='round', stroke_linecap='round') for i in range(len(target_layers))] + n = 5 + rainbow = rainbow[n:] + rainbow[:n] + out_paths = [] svg_stuff = [*out_paths] # See https://coil32.net/pcb-coil.html for details - d_inside = diameter - 2*(pitch*turns - clearance) - d_avg = (diameter + d_inside)/2 - phi = (diameter - d_inside) / (diameter + d_inside) + d_avg = (outer_diameter + inner_diameter)/2 + phi = (outer_diameter - inner_diameter) / (outer_diameter + inner_diameter) c1, c2, c3, c4 = 1.00, 2.46, 0.00, 0.20 L = mu_0 * turns**2 * d_avg*1e3 * c1 / 2 * (log(c2/phi) + c3*phi + c4*phi**2) - print(f'Outer diameter: {diameter:g} mm', file=sys.stderr) + print(f'Outer diameter: {outer_diameter:g} mm', file=sys.stderr) print(f'Average diameter: {d_avg:g} mm', file=sys.stderr) - print(f'Inner diameter: {d_inside:g} mm', file=sys.stderr) + print(f'Inner diameter: {inner_diameter:g} mm', file=sys.stderr) print(f'Fill factor: {phi:g}', file=sys.stderr) print(f'Approximate inductance: {L:g} µH', file=sys.stderr) - make_pad = lambda num, x, y: kicad_fp.Pad( + make_pad = lambda num, layer, x, y: kicad_fp.Pad( number=str(num), type=kicad_fp.Atom.smd, shape=kicad_fp.Atom.circle, at=kicad_fp.AtPos(x=x, y=y), size=kicad_fp.XYCoord(x=trace_width, y=trace_width), - layers=[target_layer], + layers=layer, clearance=clearance, zone_connect=0) @@ -149,9 +252,9 @@ def generate(outfile, turns, diameter, via_diameter, via_drill, trace_width, cle layer=layer, stroke=kicad_fp.Stroke(width=trace_width)) - make_arc = lambda x1, y1, x2, y2, xc, yc, layer: kicad_fp.Arc( + make_arc = lambda x1, y1, x2, y2, xm, ym, layer: kicad_fp.Arc( start=kicad_fp.XYCoord(x=x1, y=y1), - mid=kicad_fp.XYCoord(x=xc, y=yc), + mid=kicad_fp.XYCoord(x=xm, y=ym), end=kicad_fp.XYCoord(x=x2, y=y2), layer=layer, stroke=kicad_fp.Stroke(width=trace_width)) @@ -170,16 +273,40 @@ def generate(outfile, turns, diameter, via_diameter, via_drill, trace_width, cle pads = [] lines = [] arcs = [] - turns_per_layer = ceil((turns-1) / len(target_layers)) - print(f'Splitting {turns} turns into {len(target_layers)} layers using {turns_per_layer} turns per layer plus one weaving turn.', file=sys.stderr) - sector_angle = 2*pi / turns_per_layer - ### DELETE THIS: - d_inside = diameter/2 # FIXME DEBUG - ### - - def do_spiral(path, r1, r2, a1, a2, layer, fn=64): + + def arc_approximate(points, layer, tolerance=0.02, level=0): + indent = ' ' * level + #print(f'{indent}arc_approximate {len(points)=}', file=sys.stderr) + if len(points) < 3: + raise ValueError() + + i_mid = len(points)//2 + + x0, y0 = points[0] + x1, y1 = points[i_mid] + x2, y2 = points[-1] + + if len(points) < 5: + #print(f'{indent} -> interp last points', file=sys.stderr) + yield make_arc(x0, y0, x2, y2, x1, y1, layer) + + # https://stackoverflow.com/questions/56224824/how-do-i-find-the-circumcenter-of-the-triangle-using-python-without-external-lib + d = 2 * (x0 * (y2 - y1) + x2 * (y1 - y0) + x1 * (y0 - y2)) + cx = ((x0 * x0 + y0 * y0) * (y2 - y1) + (x2 * x2 + y2 * y2) * (y1 - y0) + (x1 * x1 + y1 * y1) * (y0 - y2)) / d + cy = ((x0 * x0 + y0 * y0) * (x1 - x2) + (x2 * x2 + y2 * y2) * (x0 - x1) + (x1 * x1 + y1 * y1) * (x2 - x0)) / d + r = dist((cx, cy), (x1, y1)) + if any(abs(dist((px, py), (cx, cy)) - r) > tolerance for px, py in points): + #print(f'{indent} -> split', file=sys.stderr) + yield from arc_approximate(points[:i_mid+1], layer, tolerance, level+1) + yield from arc_approximate(points[i_mid:], layer, tolerance, level+1) + + else: + yield make_arc(x0, y0, x2, y2, x1, y1, layer) + #print(f'{indent} -> good fit', file=sys.stderr) + + def do_spiral(layer, r1, r2, a1, a2, start_frac, end_frac, fn=64): + fn = ceil(fn * (a2-a1)/(2*pi)) x0, y0 = cos(a1)*r1, sin(a1)*r1 - path.move(x0, y0) direction = '↓' if r2 < r1 else '↑' dr = 3 if r2 < r1 else -3 label = f'{direction} {degrees(a1):.0f}' @@ -187,64 +314,118 @@ def generate(outfile, turns, diameter, via_diameter, via_drill, trace_width, cle [label], x=str(x0 + cos(a1)*dr), y=str(y0 + sin(a1)*dr), - style=f'font: 1px bold sans-serif; fill: {path.attrs["stroke"]}')) + text_anchor='middle', + style=f'font: 1px bold sans-serif; fill: {rainbow[layer%len(rainbow)]}')) + xn, yn = x0, y0 + points = [(x0, y0)] for i in range(fn+1): + r, g, b, _a = mpl.cm.plasma(start_frac + (end_frac - start_frac)/fn * (i + 0.5)) + path = SVGPath(fill='none', stroke=f'#{round(r*255):02x}{round(g*255):02x}{round(b*255):02x}', stroke_width=trace_width, stroke_linejoin='round', stroke_linecap='round') + svg_stuff.append(path) + xp, yp = xn, yn r = r1 + i*(r2-r1)/fn a = a1 + i*(a2-a1)/fn xn, yn = cos(a)*r, sin(a)*r + path.move(xp, yp) path.line(xn, yn) + points.append((xn, yn)) + #lines.append(make_line(xp, yp, xn, yn, layer_pair[layer])) + + arcs.extend(arc_approximate(points, layer_pair[layer], arc_tolerance)) svg_stuff.append(Tag('text', [label], x=str(xn + cos(a2)*-dr), y=str(yn + sin(a2)*-dr + 1.2), - style=f'font: 1px bold sans-serif; fill: {path.attrs["stroke"]}')) - - - print(f'{turns=} {turns_per_layer=} {len(target_layers)=}', file=sys.stderr) - - start_radius = d_inside/2 - end_radius = diameter/2 - - inner_via_ring_radius = start_radius - via_diameter/2 - inner_via_angle = 2*asin(via_diameter/2 / inner_via_ring_radius) - - outer_via_ring_radius = end_radius + via_diameter/2 - outer_via_angle = 2*asin(via_diameter/2 / outer_via_ring_radius) - print(f'inner via ring @ {inner_via_ring_radius:.2f} mm (from {start_radius:.2f} mm)', file=sys.stderr) - print(f' {degrees(inner_via_angle):.1f} deg / via', file=sys.stderr) - print(f'outer via ring @ {outer_via_ring_radius:.2f} mm (from {end_radius:.2f} mm)', file=sys.stderr) - print(f' {degrees(outer_via_angle):.1f} deg / via', file=sys.stderr) - - for n in range(turns-1): - layer_n = n % len(target_layers) - layer = target_layers[layer_n] - layer_turn = floor(n / len(target_layers)) - print(f' {layer_n=} {layer_turn=}', file=sys.stderr) - - start_angle = sector_angle * (layer_turn - layer_n / len(target_layers)) - end_angle = start_angle + (turns_per_layer + 1/len(target_layers)) * sector_angle - - if layer_n % 2 == 1: - start_radius, end_radius = end_radius, start_radius - - do_spiral(out_paths[layer_n], start_radius, end_radius, start_angle, end_angle, layer_n) + text_anchor='middle', + style=f'font: 1px bold sans-serif; fill: {rainbow[layer%len(rainbow)]}')) + + return (x0, y0), (xn, yn) + + if via_offset is None: + via_offset = max(0, (via_diameter-trace_width)/2) + print(f'Autocalculated {via_offset=}', file=sys.stderr) + + sector_angle = 2*pi / twists + total_angle = twists*2*sweeping_angle + + inverse = {} + for i in range(twists): + #print(i, i*turns % twists, file=sys.stderr) + inverse[i*turns%twists] = i + + svg_vias = [] + for i in range(twists): + start_angle = i*sector_angle + fold_angle = start_angle + sweeping_angle + end_angle = fold_angle + sweeping_angle + + x = inverse[i]*floor(2*sweeping_angle / (2*pi)) * 2*pi + (x0, y0), (xn, yn) = do_spiral(0, outer_radius, inner_radius, start_angle, fold_angle, (x + start_angle)/total_angle, (x + fold_angle)/total_angle) + do_spiral(1, inner_radius, outer_radius, fold_angle, end_angle, (x + fold_angle)/total_angle, (x + end_angle)/total_angle) + + xv, yv = inner_via_ring_radius*cos(fold_angle), inner_via_ring_radius*sin(fold_angle) + pads.append(make_via(xv, yv, layer_pair)) + if via_offset > 0: + lines.append(make_line(xn, yn, xv, yv, layer_pair[0])) + lines.append(make_line(xn, yn, xv, yv, layer_pair[1])) + svg_vias.append(Tag('circle', cx=xv, cy=yv, r=via_diameter/2, stroke='none', fill='white')) + svg_vias.append(Tag('circle', cx=xv, cy=yv, r=via_drill/2, stroke='none', fill='black')) + + if i > 0: + xv, yv = outer_via_ring_radius*cos(start_angle), outer_via_ring_radius*sin(start_angle) + pads.append(make_via(xv, yv, layer_pair)) + if via_offset > 0: + lines.append(make_line(x0, y0, xv, yv, layer_pair[0])) + lines.append(make_line(x0, y0, xv, yv, layer_pair[1])) + svg_vias.append(Tag('circle', cx=xv, cy=yv, r=via_diameter/2, stroke='none', fill='white')) + svg_vias.append(Tag('circle', cx=xv, cy=yv, r=via_drill/2, stroke='none', fill='black')) + + pads.append(make_pad(1, [layer_pair[0]], outer_radius, 0)) + pads.append(make_pad(2, [layer_pair[1]], outer_radius, 0)) + + svg_stuff += svg_vias + + svg_stuff.append(Tag('path', d=f'M {inner_radius} 0 L {outer_radius} 0', stroke=rainbow[n+1], fill='none', + stroke_width='0.05mm', stroke_linecap='round')) + ntraces = int(turns_per_layer)+1 + alpha = [0] * ntraces + for i in range(ntraces): + c = inner_radius + (outer_radius-inner_radius) / turns_per_layer * i + #dalpha = dy / c + #dx / dalpha = (outer_radius - inner_radius) / sweeping_angle + #c * (dx / dy) = (outer_radius - inner_radius) / sweeping_angle + #dx / dy = (outer_radius - inner_radius) / sweeping_angle / c + dx = (outer_radius - inner_radius) / sweeping_angle / c + alpha[i] = atan(dx) + dy = 0.3 + dx *= dy + r = trace_width/2 / cos(alpha[i]) + svg_stuff.append(Tag('path', d=f'M {c-r+dx} {-dy} L {c-r-dx} {dy}', stroke=rainbow[n+1], fill='none', + stroke_width='0.05mm', stroke_linecap='round')) + svg_stuff.append(Tag('path', d=f'M {c+r+dx} {-dy} L {c+r-dx} {dy}', stroke=rainbow[n+1], fill='none', + stroke_width='0.05mm', stroke_linecap='round')) + + #print(f'spiral angle {degrees(alpha[i]):.2f}', file=sys.stderr) + + for i, (a1, a2) in enumerate(zip(alpha[::-1], alpha[1::])): + amean = (a2+a1)/2 + pitch = (outer_radius - inner_radius) / turns_per_layer + clearance = pitch - trace_width + clearance *= cos(amean) + + x, y = inner_radius + (i + 1/2)*pitch, -0.5 + svg_stuff.append(Tag('text', + [f'{clearance:.5f}mm'], + x=x, + y=y, + text_anchor='start', + transform=f'rotate(-45 {x} {y})', + style=f'font: 1px bold sans-serif; fill: {rainbow[n+1]}')) svg_file('/tmp/test.svg', svg_stuff, 100, 100, -50, -50) - if counter_clockwise: - for p in pads: - p.at.y = -p.at.y - - for l in lines: - l.start.y = -l.start.y - l.end.y = -l.end.y - - for a in arcs: - a.start.y = -a.start.y - a.end.y = -a.end.y - if footprint_name: name = footprint_name elif outfile: @@ -253,7 +434,7 @@ def generate(outfile, turns, diameter, via_diameter, via_drill, trace_width, cle name = 'generated_coil' if keepout_zone: - r = diameter/2 + keepout_margin + r = outer_diameter/2 + keepout_margin tol = 0.05 # mm n = ceil(pi / acos(1 - tol/r)) pts = [(r*cos(a*2*pi/n), r*sin(a*2*pi/n)) for a in range(n)] @@ -269,7 +450,7 @@ def generate(outfile, turns, diameter, via_diameter, via_drill, trace_width, cle name=name, generator=kicad_fp.Atom('GerbonaraTwistedCoilGenV1'), layer='F.Cu', - descr=f"{turns} turn {diameter:.2f} mm diameter twisted coil footprint, inductance approximately {L:.6f} µH. Generated by gerbonara'c Twisted Coil generator, version {__version__}.", + descr=f"{turns} turn {outer_diameter:.2f} mm diameter twisted coil footprint, inductance approximately {L:.6f} µH. Generated by gerbonara'c Twisted Coil generator, version {__version__}.", clearance=clearance, zone_connect=0, lines=lines, |