Partially or Completely Faulty eMMC (Guide)

Partially or Completely Faulty eMMC: Symptoms, Diagnostics, and Recovery Insights

Because of their efficiency and small size, eMMC (embedded MultiMediaCard) chips are frequently used for storage in a variety of devices. Nevertheless, eMMC chips are susceptible to errors, which can vary from inadequate socket contact to total failure, just like any other hardware part. This article examines possible recovery options, diagnostic findings, and symptoms of malfunctioning eMMC chips.

Symptoms of Faulty eMMC Chips

The most common symptoms of a faulty eMMC or poor contact in the socket include the following error messages:

1. CMD Timeout Error

   • Error Message: Can not init device. Reason: CMD Timeout Error

2. OCR Ready Timeout Error

   • Error Message: Can not init device. Reason: OCR Ready Timeout Error [Check VCC or eMMC DEAD]

3. Password Locked Device

• Error Message:
• Can not init device. Reason: CARD is Password Locked
• EMMC Password Locked: Yes

Behavior of Half-Dead Chips

In some cases, the eMMC chip may not be entirely dead but enter a “boot mode,” where only limited functionality is available. This can often be identified by examining the chip’s CID (Card Identification Data).

Examples of CID Data from Half-Dead Chips:

1. SanDisk

   • EMMC NAME: SDM 032, S/N: FFFFFFFF, rev. 90
   • Capacity: 30 MB (000001E9C000)

2. Hynix

   • EMMC NAME: M MOR, S/N: 00000000, rev. 00
   • Capacity: 128 MB (000008000000)

3. FORESEE

   • EMMC NAME: (Blank), S/N: FFFFFFFF, rev. FF
   • EMMC NAME (HEX): 000000000000

4. Samsung

• EMMC NAME: 000000, S/N: 20110726, rev. 56
• EMMC NAME (HEX): 303030303030

Key Insights into Samsung eMMC Chips

A specific indicator of Samsung eMMC chips entering boot mode is the following pattern in their CID data:

• EMMC NAME: 000000
• Revision: 0x56

In many cases, Samsung eMMC chips up to MMC revision 5.0 (and some early rev 5.0 models) allow for firmware restoration to exit boot mode. However, this recovery is not a guaranteed fix and depends heavily on the root cause of the issue. Often, even after recovery, the chip’s functionality may be limited or its lifespan significantly reduced.

Recovery Limitations for Non-Samsung eMMC Chips

For other brands such as SanDisk, Hynix, and FORESEE, eMMC firmware recovery is generally not possible once the chip enters boot mode. These chips are often in boot mode due to severe memory cell wear, indicating that they are at the end of their operational life. Attempting to recover such chips may temporarily revive them, but long-term reliability cannot be assured.

Considerations and Future Updates

This article serves as an initial exploration into the symptoms and recovery possibilities for partially or completely faulty eMMC chips. It is essential to note:

• Not all listed behaviors guarantee specific recovery outcomes.
• Recovery attempts may sometimes exacerbate the issue.
• As technology evolves, new recovery techniques may emerge.

Over time, inaccuracies in this article will be corrected, and additional insights will be added to reflect advancements in diagnostic and recovery methods.