Emmc | Cid Decoder

# OID oid = cid_bytes[2] print(f"OEM ID (OID): 0xoid:02X")

This report explains the structure and decoding process for the eMMC Card Identification (CID) register, provides decoding algorithms, example decodes, and a small reference implementation in Python to parse a 128-bit CID value into human-readable fields.

The 128 bits are divided into 16 bytes (BE). The JESD84-B51 standard defines the following fields: emmc cid decoder

Most CID decoders are either small software utilities or web-based scripts. They work by taking a 32-character hexadecimal string and using bitwise shifts and masks to isolate the specific bits assigned to each field. For example, to find the , a decoder looks at bits [15:8] of the register, where 4 bits represent the month and 4 bits represent the year (offset from 2010 or 1997 depending on the specification version). Conclusion

: Look up 0x15 in the JEDEC manufacturer registry. This value maps directly to Samsung . Other common IDs include 0x45 (SanDisk), 0x13 (Micron), 0x90 (SK Hynix), and 0x70 (Kingston). Step 2: Parsing the Product Name (PNM) Raw Bytes : 0x41 0x4a 0x34 0x35 0x61 0x32 # OID oid = cid_bytes[2] print(f"OEM ID (OID):

One of the most practical uses of CID decoding is detecting counterfeit or low-quality eMMC devices:

An 8-bit token assigned by JEDEC to identify the chip manufacturer (e.g., Samsung, SK Hynix, Micron, SanDisk). They work by taking a 32-character hexadecimal string

cid = "150100303136473332e03f5d9600b46d"