Unlocking the Medusa ETU: How to Program the Poseidon CSI Theseus AEG with the Medusa App

The Poseidon CSI Theseus comes pre-installed with the Medusa ETU. In this guide we’ll walk you step-by-step through connecting the Medusa App, understanding each control, and customizing the ETU to match your play style.

Quick overview: what is the Medusa ETU?

The Medusa ETU is a fully Bluetooth-enabled electronic trigger unit (ETU) that lets you control firing modes, sensitivity, burst settings, tracer control, binary trigger and battery type directly from your smartphone using the Medusa App. It’s factory-installed in the Poseidon CSI Theseus AEG and gives you precise, on-the-fly configuration without tools.

Before you begin — safety & prep

• Always keep the muzzle pointed in a safe direction.
• Remove magazine and confirm the gun is clear before doing any adjustments or test firing.
• Make sure your phone’s Bluetooth is on and the gun battery is charged to avoid interrupted connections.

Step-by-step: connect the Medusa App

1. Turn your phone’s Bluetooth ON.
2. Insert a charged battery into the Poseidon CSI Theseus (do not pull the trigger).
3. Open the Medusa App on your phone — you’ll be prompted to connect. Tap Connect.
4. When connected you’ll land on the main dashboard showing mode, round count, and battery voltage.

Understanding the main dashboard

The top status window displays your current selector state and highlights the selected mode:

• Safe
• Semi
• Auto

When you move the physical selector, the app highlights the corresponding word so the app and gun stay in sync.

Key app features explained

Round count & voltage

Track how many rounds you’ve fired during a session and monitor battery voltage so you don’t get stranded in the middle of a game.

Selector switch visual

A graphical selector mirrors the physical switch movement for visual confirmation of your selected mode.

Binary mode (dual-bullet icon)

Activates binary trigger functionality. To enable:

1. Place the selector on Semi.
2. Tap the dual-bullet/binary icon in the app (or press the slider control) to activate binary mode.

Tracer unit control (light icon)

Toggle the built-in tracer unit on or off via the app. Use the light icon to switch between tracer enabled/disabled.

Fire button (app test fire)

The fire button in the app lets you perform a test fire electronically without pulling the physical trigger. Use this for quick checks — always follow safety steps first.

Burst mode

To set burst length:

1. Place selector on Auto.
2. Choose your desired burst setting at the bottom of the control panel (e.g., 2-round, 3-round bursts).

Sensitivity settings

The sensitivity panel gives you five settings (1–5): 1 = most sensitive, 5 = least sensitive. Access this while the selector is on Semi and choose the setting that best matches your trigger feel.

Battery type selection

Set the correct battery chemistry and voltage so the ETU reads and displays accurate voltage and current. Options typically include:

• Li-Po 7.4V / 11.1V
• Li-Fe 7.4V
• Auto-detec