Note:
If the chip is removed from a mobile phone, there are two problems that need attention:
1. The file system in the chip is still ext3/4, which Windows cannot recognize. It needs to be opened with DiskGenius or an Ubuntu system, or reformatted to the exFAT/FAT32 file system. DiskGenius software is required to open and format the partition; otherwise, using the computer's built-in system to open it will constantly trigger popup windows indicating that it cannot be formatted.
2. The constant popup asking to format a certain partition is normal because there really are a lot of partitions (over 40). To use it as a regular TF card, it needs to be repartitioned. Instructions for PCB prototyping: The PCB thickness should be 0.8, and the edges of the contact points should be beveled without soldering. If it fails, it is recommended to consult the corresponding eMMC manual to see if it supports 4-line mode. For eMMC 5.1 chips, please use a USB 3.0 card reader. Some card readers that do not support the MMC protocol cannot recognize it.