RMBD (Magisk Modules)

This repository contains two Magisk modules designed to reduce idle battery drain caused by Wi-Fi multicast traffic on Android devices (especially Pixels), while preserving usability for discovery-based features like Chromecast and smart-home setup.

Both modules work by controlling the Wi-Fi interface multicast flag, which directly affects:

• Radio wakeups (e.g. dhdpcie_host_wake)
• Screen-off idle drain
• Doze being interrupted

Root (Magisk) is required.

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Background (Why this exists)

Many apps (Google Play services, Instagram, WeChat, media apps, etc.) hold multicast locks unnecessarily.
This causes:

• High screen-off battery drain
• CPU + Wi-Fi radio being pulled out of suspend
• WifiMulticastOn staying active for hours
• Frequent Wi-Fi driver interrupts

Android does not aggressively police multicast usage by default.

These modules fix that.

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Modules Overview

1️⃣ RMBD (Hard OFF)

Best for: Maximum battery life, minimal discovery usage

What it does

• Disables Wi-Fi multicast globally
• Multicast stays OFF as long as the module is enabled
• Requires reboot to apply
• Discovery features (Chromecast, smart-home pairing) will not work while enabled

Behavior

State	Multicast
Boot	OFF
Screen ON	OFF
Screen OFF	OFF

Pros

• Maximum reduction of idle drain
• Simple, stable, zero background logic

Cons

• No Chromecast / mDNS / UPnP discovery while enabled

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2️⃣ RMBD_screen_aware (Recommended for most users)

Best for: Users who frequently use Chromecast or smart-home discovery

What it does

• Automatically disables multicast when the screen is OFF
• Automatically re-enables multicast when the screen is ON
• No manual toggling
• Discovery works normally while you are actively using the phone

Behavior

Screen state	Multicast	Discovery
ON	ON	Works
OFF	OFF	Disabled

Pros

• Large reduction in idle battery drain
• Chromecast / smart-home still works
• Fully automatic

Cons

• Small background loop (5s polling, negligible power cost)

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Which module should I use?

Use case	Recommended module
Maximum battery life	RMBD
Chromecast / smart-home user	RMBD_screen_aware
Mostly idle phone	Either
Forgetful about toggles	RMBD_screen_aware

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Installation

Requirements

• Rooted Android device
• Magisk installed
• Reboot capability

Steps

1. Download the desired ZIP:

   • RMBD.zip for max battery saving

     or

   • RMBD_screen_aware.zip take slight hit in battery but keep smarthome discovery and chromecast working

2. Open Magisk
3. Go to Modules → Install from storage
4. Select the ZIP
5. Reboot

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Verification (optional)

After reboot:

Screen ON

adb shell su -c "ip link show wlan1 | grep MULTICAST"