Drawn against the real Freenove GPIO Extension Board, so every hole in here is the hole you actually use. The left half never changes — only the coloured bundle on the right comes out when Bodhi swaps sensors.
The board straddles the channel at positions 13–32, with its pins in columns d and g. Its silkscreen labels are drawn in place, so you can find any GPIO by eye.
d–g, so e and f are live but blocked. Everything taps from a/b/c below or h/i/j above — that constraint is what drives the routing lanes.d side; all four LEDs are on the g side. Nothing has to jump the channel.Your breadboard currently has the 74HC595, the LED bar graph, an accelerometer breakout and the coin-cell rig on it from positions 34 down. These layouts assume 33–63 is empty.
The silkscreen labels were read straight off your photo. The position numbers were derived by lining the breadboard's printed ruler up against the label rows — it agrees in four places (15↔36/VP, 20↔33, 25↔12, 30↔3.3V), but it's still read off a photograph.
Before you commit wire to board, confirm one pin: GPIO 13 should sit two positions below GPIO 12 on the left-hand labels. If that holds, the whole map holds. Full details in docs/extension-board.md.