MCP — Mode Control Panel
Full build log for the 737 MAX Mode Control Panel: panel design, encoder wiring, backlighting, and CockpitConnect configuration.
Overview
The Mode Control Panel (MCP) is the autopilot brain of the 737 MAX flight deck. It controls speed, heading, altitude, vertical speed, and the various autopilot modes via a row of encoders, buttons, and seven-segment displays.
This page documents the complete build process — from initial measurements and CAD work through to final wiring and CockpitConnect configuration.
Panel Design
The MCP panel was drawn from scratch in Fusion 360 using reference photos and dimension data from the PMDG documentation. All cutouts are parametric, so adjusting the encoder hole diameter cascades across the full panel.
The panel is cut from 3mm black acrylic with a white engrave for the legends, giving a clean backlit look.
Components Used
| Part | Spec | Qty |
|---|---|---|
| Rotary encoders | 24-pulse with push | 6 |
| Seven-segment displays | 0.56" common cathode | 12 |
| Backlight LEDs | 3mm warm white | 42 |
| Toggle switches | Taiway 2-pos | 8 |
| Pushbuttons | Momentary, flush | 14 |
| Controller | ESP32-S3-DevKitC-1 | 1 |
Wiring
Each encoder connects to two GPIOs on the ESP32-S3. The pushbuttons and switches sit on MCP23017 I²C expanders, and the seven-segment displays are driven by a MAX7219 chain to keep the pin count manageable. See Electronics for the pin table.
CockpitConnect Configuration
All inputs and outputs are bound in Flows in CockpitConnect. Each encoder step sends an X-Plane 12 autopilot command (for example sim/autopilot/heading_up), and each display follows its autopilot dataref, so the MCP always shows what the simulator has selected.
Photos
Photos coming soon — panel is complete and functional.