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Datasheet

2021-08-19

DS-AT25FF321A-181

Revision J

AT25FF321A

32-Mbit, 1.65 V - 3.6 V SPI Serial Flash Memory

with Multi-I/O Support

Status Registers

The device contains five Status registers (SR) described in the following subsections. The Status registers can be read to deter-

mine the device's ready/busy status, as well as the status of many other functions such as hardware locking and software

protection.

5.1 REGISTER STRUCTURE AND UPDATES

In the AT25FF321A device there are two sets of Status registers. One set is implemented in hardware and is accessed as Status

registers 1 - 5. These are known as volatile registers as they lose their data during a device reset. Also, the device keeps a copy

of the Status registers in memory. These are known as non-volatile registers because they are stored in the Flash and are not

affected by a device reset. On power up, the non-volatile contents of the memory are copied to the Status registers. See Section

5.2.2 for more information on volatile and non-volatile register types.

The AT25FF321A provides two methods for updating the Status Registers. When the Write to Status Register command is

preceded by the Volatile Status Register Write Enable (50h) command, only the flip-flops holding the Status register bits are

updated; the non-volatile memory dedicated to the Status registers is not updated. When the Write to Status Register command

is preceded with a Write Enable (06h) command, then both the flip-flops holding the Status register bits and the non-volatile

memory dedicated to the Status registers are updated. This concept is shown in Figure 24.

The main difference between these two commands is the time required to execute them. Accesses to memory are much slower

by default. So for the 50h command, the write is to the volatile Status registers only which is very fast. For the 06h command, the

write is not only to the Status registers, but also to non-volatile memory which is much slower.

Figure 24: AT25FF321A Register Structure

Status

Registers

Memory

50h

06h

Power Up

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