Name: O2Micro Integrated MMC SD controller Driver
Author: O2Micro

Question 1

Install fails or rolls back?

Accepted Answer

The O2Micro MMC/SD INF may be unsigned or blocked by Windows. Run the installer as administrator, extract the package, and update the controller manually in Device Manager (*Update driver > Browse > Let me pick > Have Disk*). If Windows blocks it, disable driver signature enforcement only for the install, then re-enable.

Question 2

SD card/device not detected?

Accepted Answer

Confirm the SD controller is enabled in BIOS/UEFI and not disabled by a physical switch. In Device Manager, uninstall the O2Micro controller with “Delete driver software,” restart, and rescan. Reseat the card and test another SD card to rule out media failure.

Question 3

Version conflicts after Windows Update?

Accepted Answer

Windows may replace the OEM driver with a generic Microsoft SD host controller. Use *Roll Back Driver* or reinstall the O2Micro package, then set Device Installation Settings to prevent automatic driver replacement if stable operation is required.