Master firmware with WiFi AP, REST API and existing web UI
IMU Master and IMU Slave support with robust MPU6050 access
shared telemetry protocol for multiple device types
UI support for both IMU nodes and future CoG scale nodes
battery monitoring with optional hide/disable behavior on unsupported Master hardware

Prepared but not fully implemented yet:

dedicated HX711-based CoG scale firmware
model profiles with support spacing, leading-edge offset and target CoG
scale calibration workflow in the web UI

Architecture

IMU Slave(s) ------\
                    \
CoG Scale Node(s) ----> Master ESP32 ----> WiFi AP ----> Browser UI
                    /
Master local IMU --/

Device roles

Master
- hosts SkyLogic-AeroAlign
- receives ESP-NOW telemetry
- serves the web UI and REST API
- can also have its own MPU6050
IMU Slave
- remote angle node
- sends pitch, roll and yaw fields as angle telemetry
CoG Scale
- future load-cell node
- will send front weight, rear weight and computed CoG in the same shared packet

Telemetry Protocol

The shared packet format is defined in telemetry_protocol.h.

Device types currently defined:

DEVICE_TYPE_IMU
DEVICE_TYPE_COG_SCALE
DEVICE_TYPE_HYBRID

For IMU nodes:

pitch, roll, yaw are angles

For CoG scale nodes:

pitch => front support weight in grams
roll => rear support weight in grams
yaw => CoG position in millimeters

Hardware Overview

IMU nodes

Use:

ESP32-C3 or ESP32-S3
MPU6050
LiPo, charger and 3.3V supply
optional battery divider depending on node

See sensor_node_wiring.md.

CoG scale

Planned hardware stack:

ESP32-C3 or ESP32-S3
two HX711 boards
two load cells
rigid support spacing and repeatable fixtures

See cog_scale_wiring.md.

BOM

The BOM is now maintained as a current component overview instead of placeholder shop links:

bom.csv

Firmware Layout

Existing

Planned

firmware/cog_slave
- HX711 reading
- tare and scale calibration
- CoG computation
- ESP-NOW transmission as DEVICE_TYPE_COG_SCALE

Build

Master:

cd firmware/master
pio run

Slave:

cd firmware/slave
pio run -e esp32-s3
pio run -e slave2-s3

Current Configuration Notes

Slave Master MAC

The Slave now reads the Master MAC from config.cpp, not config.h.

Master battery monitoring

On ESP32-S3 Master boards the battery ADC path is optional. If the divider is not fitted, the firmware and UI hide the battery value instead of showing dummy data.

CoG Math

With front and rear supports spaced by L:

x_cog_from_front_support = rear_weight / (front_weight + rear_weight) * L

If the front support is offset from the wing leading edge:

x_cog_from_leading_edge = support_offset_from_leading_edge + x_cog_from_front_support

The current design note is in AEROALIGN_COG_INTEGRATION.md.

Workflow Plan

The planned operating workflow and the recommended hardware roles are documented in:

3D Printed Parts

The CAD readme now covers both IMU parts and planned CoG fixtures:

hardware/cad/README.md

Recommended Next Work

Add firmware/cog_slave with HX711 support.
Add tare and calibration endpoints in the Master API.
Add a dedicated CoG tab in the web UI.
Add aircraft profiles in NVS.
Finalize mechanical design for the two support fixtures.