OSC Controller

A wireless sensor interface built on an ESP8266 (NodeMCU v2) that reads analog inputs through a 16-channel multiplexer and transmits them as OSC messages over UDP, letting physical knobs and sensors control software like Max MSP or TouchDesigner without a cable in sight.

Overview

The controller reads up to 16 analog sensors through a single ADC pin via a CD74HC4067 multiplexer. Each sensor reading is normalized and dispatched as an OSC message over Wi-Fi, typed by its intended use:

• Sensor: Raw normalized value for generic mappings
• MIDI: Normalized to 0–127 for direct MIDI parameter control
• Cutoff: Scaled for filter cutoff frequency ranges

An I2C LCD displays live sensor values, and Wi-Fi credentials are stored in a JSON config file on the device LittleFS filesystem, configurable via serial monitor without reflashing.

Hardware

• NodeMCU v2 (ESP8266): Wi-Fi microcontroller
• CD74HC4067 16-channel analog multiplexer: Expands the single ADC to 16 inputs
• 16×2 I2C LCD: Live readout of active sensor values
• Analog sensors wired to multiplexer channels (potentiometers, FSRs, and photoresistors)

Schematic

Architecture

Three custom libraries handle the separation of concerns:

OSCInstance manages Wi-Fi setup and OSC transmission. It connects to the network, opens a UDP socket, and sends typed OSC messages to a configurable target IP and port.

Multiplexer wraps the CD74HC4067: it sets the S0–S3 select pins to route each channel through the shared analog pin, and debounces readings so only genuine changes trigger a message.

Settings loads Wi-Fi credentials from a config.json file on LittleFS. If no config is found, it scans available networks and prompts for credentials over serial, then persists them for future boots.

Configuration

Flash a config.json to the device data partition:

{
  "network": {
    "ssid": "your_ssid",
    "password": "your_password"
  },
  "osc": {
    "host": ""
  }
}

Use PlatformIO’s Build Filesystem Image → Upload Filesystem Image tasks to write it. Alternatively, connect over serial and select a network interactively; credentials are saved to flash automatically.

What It Became

This project was the seed for WirelessMIDI, a plug-in module designed to retrofit any MIDI instrument with wireless capability. The OSC Controller proved the ESP8266 + UDP stack was reliable enough for real-time performance use, and the multiplexer approach carried forward into the new design.

Github