1 files changed, 127 insertions, 0 deletions
diff --git a/diagrams/backplane-connector-diagram.typ b/diagrams/backplane-connector-diagram.typ
new file mode 100644
index 0000000..0b2d254
--- /dev/null
+++ b/diagrams/backplane-connector-diagram.typ
@@ -0,0 +1,127 @@
+#import "../lib/unify.typ": qty
+#import "@preview/cetz:0.5.2"
+
+#figure(
+  cetz.canvas({
+    import cetz.draw: *
+
+    let dx = 1.0
+    let top-y = 0.55
+    let bot-y = -0.55
+
+    // Outer mounting flange / metal ears
+    rect(
+      (-2.0, -1.4),
+      (14.0, 1.4),
+      rx: 0.2,
+      fill: luma(245),
+      stroke: 1pt + luma(100),
+    )
+
+    // Left and right chassis mounting screw holes
+    circle((-1.3, 0), radius: 0.35, fill: luma(220), stroke: 1pt + luma(120))
+    circle((-1.3, 0), radius: 0.20, fill: white, stroke: 0.8pt + luma(100))
+    circle((13.3, 0), radius: 0.35, fill: luma(220), stroke: 1pt + luma(120))
+    circle((13.3, 0), radius: 0.20, fill: white, stroke: 0.8pt + luma(100))
+
+    // D-Sub trapezoidal shroud outline
+    line(
+      (-0.7, 1.15),
+      (12.7, 1.15),
+      (12.2, -1.15),
+      (-0.2, -1.15),
+      close: true,
+      fill: luma(230),
+      stroke: 1.5pt + black,
+    )
+
+    // Shell Earth ground connection reference
+    line((-0.45, -1.15), (-0.45, -2.0), stroke: (
+      paint: luma(120),
+      thickness: 0.7pt,
+      dash: "dashed",
+    ))
+    content(
+      (-0.45, -2.05),
+      text(size: 7.5pt, weight: "bold")[Shell: Chassis Earth],
+      angle: -50deg,
+      anchor: "north-west",
+    )
+
+    // Top row pins (Pins 1 to 13)
+    let top-pins = (
+      ("1", [$plus qty(15.00, "V")$]),
+      ("2", [$plus qty(15.00, "V")$]),
+      ("3", [$qty(-15.00, "V")$]),
+      ("4", [$qty(-15.00, "V")$]),
+      ("5", [AGND]),
+      ("6", [AGND]),
+      ("7", [AGND]),
+      ("8", [$plus qty(10.0000, "V")$ Force]),
+      ("9", [$plus qty(10.0000, "V")$ Sense]),
+      ("10", [$qty(-10.0000, "V")$ Force]),
+      ("11", [$qty(-10.0000, "V")$ Sense]),
+      ("12", [AGND]),
+      ("13", [AGND]),
+    )
+
+    // Bottom row pins (Pins 14 to 25)
+    let bot-pins = (
+      ("14", [AGND]),
+      ("15", [AGND]),
+      ("16", [AGND]),
+      ("17", [DGND]),
+      ("18", [DGND]),
+      ("19", [$plus qty(5.0, "VD")$]),
+      ("20", [$qty(-5.0, "VD")$]),
+      ("21", [Stagger]),
+      ("22", [_Reserved_]),
+      ("23", [_Reserved_]),
+      ("24", [_Reserved_]),
+      ("25", [Chassis Earth]),
+    )
+
+    // Draw Top Pins (1-13)
+    for (i, p) in top-pins.enumerate() {
+      let x = i * dx
+      let p-num = p.at(0)
+      let p-sig = p.at(1)
+
+      circle((x, top-y), radius: 0.26, fill: white, stroke: 1pt + black)
+      content((x, top-y), text(size: 7pt, weight: "bold")[#p-num])
+
+      line((x, top-y + 0.26), (x, 1.8), stroke: (
+        paint: luma(120),
+        thickness: 0.6pt,
+      ))
+      content(
+        (x, 1.85),
+        text(size: 7.5pt)[#p-sig],
+        angle: 50deg,
+        anchor: "south-west",
+      )
+    }
+
+    // Draw Bottom Pins (14-25)
+    for (j, p) in bot-pins.enumerate() {
+      let x = (j + 0.5) * dx
+      let p-num = p.at(0)
+      let p-sig = p.at(1)
+
+      circle((x, bot-y), radius: 0.26, fill: white, stroke: 1pt + black)
+      content((x, bot-y), text(size: 7pt, weight: "bold")[#p-num])
+
+      line((x, bot-y - 0.26), (x, -1.8), stroke: (
+        paint: luma(120),
+        thickness: 0.6pt,
+      ))
+      content(
+        (x, -1.85),
+        text(size: 7.5pt)[#p-sig],
+        angle: -50deg,
+        anchor: "north-west",
+      )
+    }
+  }),
+  caption: [DB-25 backplane connector physical pinout and signal allocation diagram.],
+) <figure-backplane-connector-diagram>