5.43 Read Unique ID Number (RUID)

The Read Unique ID Number (RUID) instruction (4BH) provides access to a factory-programmed, read-only 128-bit identifier that is unique to each MC25VF256 device.

In SPI mode, the operation is initiated by issuing the 8-bit command 4BH, followed by either a three-byte or four-byte address with a value of 00000000H, and then eight dummy clock cycles. After the dummy cycles, the device outputs the 128-bit Unique ID Number.

In QPI mode, the operation is initiated by issuing the 8-bit command 4BH, followed by either a three-byte or four-byte address with a value of 00000000H. This is followed by dummy clock cycles configured through the Set Read Parameters (C0H) instruction, as defined in Table 5-12. The required number of dummy clock cycles varies according to the operating frequency. After the dummy cycles in QPI mode, the device outputs the 128-bit Unique ID Number.