CEC Adapter — PC Waking from Sleep

Modified on Mon, 27 Apr at 9:37 PM

The USB-CEC Adapter can cause a Windows PC to wake immediately after being put to sleep. This happens because Windows may treat the CEC adapter as a USB device that is allowed to wake the computer — a setting that is enabled by default for many USB devices. This article explains how to diagnose the cause and fix it.

Confirm the CEC Adapter Is the Cause

Before making any changes, confirm the adapter is actually responsible. Open a Command Prompt as Administrator and run:

powercfg /lastwake

If the CEC adapter is the cause, the output will show something like this:

Wake History Count - 1 Wake History [0]  Wake Source Count - 1  Wake Source [0]    Type :          Device    Instance Path : USB\VID_2548&PID_1002\...    Description :   USB Composite Device    Manufacturer :  (Standard USB Host Controller)

The VID 2548 and PID 1002 identify the Pulse-Eight USB-CEC Adapter. If you see this, proceed with the fix below.

Fix: Disable Wake Permission in Device Manager

Open Device Manager. You can right-click the Start button and select it from the menu.

Expand the Universal Serial Bus controllers section.

Find USB Composite Device. If there are multiple entries, right-click each one and check the Properties to identify the CEC adapter (look for VID_2548 in the Details tab under Hardware IDs).

Right-click the relevant device and select Properties.

Go to the Power Management tab.

Uncheck "Allow this device to wake the computer" and click OK.

The Power Management tab may not appear if the USB Root Hub or host controller is selected instead of the Composite Device itself. Make sure you are looking at the USB Composite Device entry, not the hub or controller above it in the tree.

Once this is unchecked, put the PC to sleep again to confirm it stays asleep. You can also verify using powercfg /lastwake after the next wake event — the CEC adapter should no longer appear as the wake source.

Why Does This Happen?

Windows assigns USB devices wake permission automatically when they are first connected. The CEC adapter receives CEC traffic from the TV or AV system even when your PC is asleep — for example, when another device on the CEC bus powers on or sends a command. Windows interprets this USB activity as a wake signal.

Disabling the wake permission does not affect the adapter's normal operation. The adapter will continue to function as expected when the PC is awake — it simply loses the ability to wake the PC from sleep.

If the Problem Persists

If the PC continues to wake after completing the steps above, check the following:

Multiple USB Composite Device entries: There may be more than one — check all of them and disable wake permission on each.
USB Root Hub entries: Expand each USB Root Hub in Device Manager, check its Power Management tab, and uncheck wake permission there too if present.
CEC Tray settings: Open the CEC Tray program and review the Power Control settings. Ensure no wake-on-CEC options are enabled within the software itself.
BIOS/UEFI settings: Some systems have a setting to allow USB devices to wake from S3/S4 sleep states at the firmware level. Check your BIOS for a setting such as "USB Wake Support" or "Wake on USB" and disable it if present.

Still waking from sleep after trying all of the above?
Contact Pulse-Eight support with the output of powercfg /lastwake and your libcec version.

UK: 01202 413 610 | US: (858) 748-8250 | support@pulse-eight.com