The author attempted to recover data from a physically broken 32 GB SD card that had been split in half. Initial attempts in 2017 to repair the damaged traces failed, resulting in the card being recognized with zero capacity. Nine years later, the author resumed the project by extracting data directly from the Samsung K9PFG08U5M memory chip.
To read the data, the author connected the chip to an STM32H723 microcontroller using a custom GPIO-based interface. The process involved identifying the pinout by comparing it with similar Samsung NAND flash datasheets and reading the chip ID: 0xEC, 0xDE, 0xD5, 0x72, 0x58, 0x42. A C# program was developed to manage page reading and data storage.
The memory structure was determined to consist of four chips, each containing two dies, totaling eight internal structures. The author read 34.2 GB of data by cycling through pages and saving the output to files. Analysis revealed a block structure where each block contains 128 pages, with specific bytes used for block marking and wear leveling management.
The recovery process required handling 8,192 bytes of data per page plus a 448-byte redundant area. The author identified that the 20th bit of the page address acts as an internal multiplexer. The final stage of the project involved analyzing the redundant area data to map the blocks and distinguish between used and empty memory segments.
