LG Intel Input Switch

Windows hotkeys for switching LG monitor inputs from an Intel GPU path.

This is a small AutoHotkey + PowerShell helper for LG monitors that ignore normal Windows DDC/CI input switching. It sends LG's vendor-specific DDC/CI input command through Intel Graphics Control Library (IGCL).

English

Why this exists

Some LG monitors accept ordinary controls like brightness through standard DDC/CI, but input switching can be different:

• Standard Windows SetVCPFeature / VCP 0x60 may return success while the monitor does nothing.
• The useful LG path is source address 0x50, VCP 0xF4, plus an input value.
• NVIDIA users can often use NvAPI-based helpers such as winddc input-alt.
• Intel users need a different path. This project uses Intel IGCL's ctlI2CAccess through PowerShell-embedded C#.

The default values in this repo are known LG vendor input values:

Input	Hex	Decimal	Script command
HDMI 1	0x90	144	hdmi1
HDMI 2	0x91	145	hdmi2
DisplayPort	0xD0	208	dp
USB-C / Thunderbolt	0xD1	209	usbc
USB-C alternate	0xD2	210	usbc2

Your monitor may use different values. Verify before assuming the table is universal.

Files

• lg-intel-switch.ps1: command-line switcher using Intel IGCL.
• Switch-LGInputs.ahk: AutoHotkey v2 hotkey wrapper.
• lg-intel-switch.log: created at runtime by the AutoHotkey wrapper.

Requirements

• Windows 10/11.
• Intel graphics driver with ControlLib.dll available. It is usually installed to C:\Windows\System32\ControlLib.dll by Intel graphics drivers.
• AutoHotkey v2 if you want hotkeys.
• PowerShell. No C# compiler project or Visual Studio install is required; PowerShell compiles the embedded C# with Add-Type.
• Administrator permission may be required for Intel I2C writes. The AHK wrapper relaunches itself elevated.

Installing AutoHotkey

The hotkey wrapper requires AutoHotkey v2, not v1.

1. Download AutoHotkey v2 from the official site: https://www.autohotkey.com/v2/
2. Run the installer. The default options are fine for this script.
3. Double-click Switch-LGInputs.ahk.
4. Approve the UAC prompt. Intel I2C writes may require administrator permission.

Official install guide: https://www.autohotkey.com/docs/v2/howto/Install.htm

Usage

Run a scan:

powershell -ExecutionPolicy Bypass -File .\lg-intel-switch.ps1 scan

Switch inputs manually:

powershell -ExecutionPolicy Bypass -File .\lg-intel-switch.ps1 hdmi1
powershell -ExecutionPolicy Bypass -File .\lg-intel-switch.ps1 hdmi2
powershell -ExecutionPolicy Bypass -File .\lg-intel-switch.ps1 dp
powershell -ExecutionPolicy Bypass -File .\lg-intel-switch.ps1 usbc
powershell -ExecutionPolicy Bypass -File .\lg-intel-switch.ps1 usbc2

For hotkeys, run Switch-LGInputs.ahk and approve the UAC prompt.

Default hotkeys:

Hotkey	Action
Ctrl + Alt + H	HDMI 1
Ctrl + Alt + 2	HDMI 2
Ctrl + Alt + D	DisplayPort
Ctrl + Alt + U	USB-C
Ctrl + Alt + Shift + U	USB-C alternate

Finding Values For Your Monitor

There is no universal public table for every LG monitor. The practical workflow is:

1. Confirm normal DDC/CI works. Tools like winddc display list detailed, ClickMonitorDDC, or ControlMyMonitor should be able to read capabilities or adjust brightness.
2. Check whether standard input switching works:

winddc --display 1 set input 17
winddc --display 1 set input 18

If the command says success but the monitor does not switch, your monitor may need LG's vendor-specific path.

3. Search for values reported by other users. Useful search terms:

LG monitor input-alt
LG monitor DDC 0xF4
LG monitor source address 0x50
LG monitor ddcutil input source

4. Try the common LG vendor values listed above.
5. If your values differ, edit the $inputValues map near the top of lg-intel-switch.ps1.
6. Run the script manually first so you can see return codes:

powershell -ExecutionPolicy Bypass -File .\lg-intel-switch.ps1 usbc

Return code 0x00000000 means Intel IGCL accepted that transaction. It does not always guarantee the monitor acted on it, so visually confirm the input changed.

Notes

The script intentionally tries several Intel I2C packet variants because IGCL abstracts low-level transactions differently across HDMI, DisplayPort, USB-C, and driver versions:

• addr6e-off50
• addr6e-off50-override
• addr37-off50
• addr37-off50-override
• addr6e-fullpacket
• addr6e-fullpacket-override

If switching fails, check lg-intel-switch.log. A successful Intel call prints 0x00000000.

Security Notes

• Read the scripts before running them. Switch-LGInputs.ahk intentionally elevates itself with UAC because Intel IGCL I2C writes may require administrator permission.
• Keep Switch-LGInputs.ahk and lg-intel-switch.ps1 in a trusted folder. The AHK wrapper runs the PowerShell script next to it.
• lg-intel-switch.ps1 accepts only the fixed commands declared in ValidateSet: scan, hdmi1, hdmi2, dp, usbc, and usbc2.
• The script does not download code, access the network, modify files except the runtime log, or persist system settings.
• ExecutionPolicy Bypass is used only for this one script invocation. It does not change the machine-wide PowerShell execution policy.
• The embedded C# restricts DLL loading to System32 before calling Intel ControlLib.dll, reducing the chance of loading an unexpected local DLL.
• The runtime log may include Intel display output handles and result codes, but it should not contain credentials or personal data.

한국어

이 프로젝트가 필요한 이유

일부 LG 모니터는 밝기 조절 같은 일반 DDC/CI 명령은 잘 받지만, 입력 전환은 표준 방식으로 동작하지 않을 수 있습니다.

• Windows 표준 VCP 0x60 입력 전환 명령은 성공처럼 보여도 실제 화면 입력이 바뀌지 않을 수 있습니다.
• LG 입력 전환에는 source address 0x50, VCP 0xF4, 입력값 조합이 필요한 경우가 있습니다.
• NVIDIA 경로에서는 winddc input-alt 같은 도구가 동작할 수 있습니다.
• Intel 경로에서는 별도 방식이 필요해서, 이 프로젝트는 Intel IGCL의 ctlI2CAccess를 PowerShell 안의 C# 코드로 호출합니다.

기본 입력값:

입력	Hex	Decimal	스크립트 명령
HDMI 1	0x90	144	hdmi1
HDMI 2	0x91	145	hdmi2
DisplayPort	0xD0	208	dp
USB-C / Thunderbolt	0xD1	209	usbc
USB-C 대체값	0xD2	210	usbc2

모든 LG 모니터에서 같은 값이 보장되는 것은 아니니, 본인 환경에서 확인해 주세요.

설치

단축키를 쓰려면 AutoHotkey v2가 필요합니다.

1. 공식 사이트에서 AutoHotkey v2를 설치합니다: https://www.autohotkey.com/v2/
2. Switch-LGInputs.ahk를 더블클릭합니다.
3. UAC 관리자 권한 요청이 뜨면 승인합니다. Intel I2C 쓰기에는 관리자 권한이 필요할 수 있습니다.

PowerShell만 직접 실행할 수도 있습니다:

powershell -ExecutionPolicy Bypass -File .\lg-intel-switch.ps1 scan
powershell -ExecutionPolicy Bypass -File .\lg-intel-switch.ps1 hdmi1
powershell -ExecutionPolicy Bypass -File .\lg-intel-switch.ps1 usbc

기본 단축키

단축키	동작
Ctrl + Alt + H	HDMI 1
Ctrl + Alt + 2	HDMI 2
Ctrl + Alt + D	DisplayPort
Ctrl + Alt + U	USB-C
Ctrl + Alt + Shift + U	USB-C 대체값

내 모니터 입력값 찾는 법

1. 먼저 DDC/CI 자체가 되는지 확인합니다. winddc display list detailed, ClickMonitorDDC, ControlMyMonitor 같은 도구로 밝기나 capability가 읽히면 출발점은 좋습니다.
2. 표준 입력 전환이 되는지 확인합니다.

winddc --display 1 set input 17
winddc --display 1 set input 18

명령은 성공하는데 실제 입력이 바뀌지 않으면 LG 전용 입력 전환 경로가 필요할 수 있습니다.

3. 아래 검색어로 같은 계열 사용자의 값을 찾아봅니다.

LG monitor input-alt
LG monitor DDC 0xF4
LG monitor source address 0x50
LG monitor ddcutil input source

4. 값이 다르면 lg-intel-switch.ps1 상단의 $inputValues를 수정합니다.
5. 단축키보다 PowerShell 명령으로 먼저 테스트하면 로그와 반환 코드를 보기 쉽습니다.

성공처럼 보이는 0x00000000이 떠도 실제 모니터가 바뀌었는지는 눈으로 확인해야 합니다.

보안 메모

• 실행 전에 스크립트를 읽어보는 것을 권장합니다.
• AHK 파일은 Intel I2C 쓰기 권한 때문에 UAC 관리자 권한으로 다시 실행됩니다.
• PowerShell 스크립트는 scan, hdmi1, hdmi2, dp, usbc, usbc2 명령만 받습니다.
• 외부 다운로드, 네트워크 접근, 시스템 설정 영구 변경은 하지 않습니다.
• ExecutionPolicy Bypass는 해당 실행 한 번에만 적용되며 시스템 정책을 바꾸지 않습니다.
• Intel ControlLib.dll은 System32에서만 로드하도록 제한했습니다.

References

• Intel Graphics Control Library: https://github.com/intel/drivers.gpu.control-library
• Windows winddc: https://github.com/choplin/winddc
• NVIDIA-oriented LG input switcher that helped document the raw LG command shape: https://github.com/meer-cha/lg-input-switch
• ddcutil, useful for investigating VCP capabilities and input values on Linux: https://github.com/rockowitz/ddcutil

Disclaimer

This sends vendor-specific DDC/CI commands to the monitor. It worked for my LG setup through Intel graphics, but monitor firmware, GPU routing, docks, and USB-C adapters can change behavior. Use at your own risk.

이 스크립트는 모니터에 vendor-specific DDC/CI 명령을 보냅니다. 모니터 펌웨어, GPU 연결 경로, 도크, USB-C 어댑터에 따라 동작이 달라질 수 있습니다. 사용은 본인 책임입니다.