Rainbow Electronics AT25DF081A - Manual (Page 31)

31
8715C–SFLSH–11/2012
AT25DF081A
11. Status Register Commands
11.1 Read Status Register
The two-byte Status Register can be read to determine the device’s ready/busy status, as well as the status of
many other functions such as Hardware Locking and Software Protection. The Status Register can be read at any
time, including during an internally self-timed program or erase operation.
To read the Status Register, the CS pin must first be asserted and the opcode of 05h must be clocked into the
device. After the opcode has been clocked in, the device will begin outputting Status Register data on the SO pin
during every subsequent clock cycle. After the second byte of the Status Register has been clocked out, the
sequence will repeat itself starting again with the first byte of the Status Register as long as the CS pin remains
asserted and the clock pin is being pulsed. The data in the Status Register is constantly being updated, so each
repeating sequence will output new data. The RDY/BSY status is available for both bytes of the Status Register
and is updated for each byte.
At clock frequencies above f
CLK
, the first two bytes of data output from the Status Register will not be valid. There-
fore, if operating at clock frequencies above f
CLK
, at least four bytes of data must be clocked out from the device in
order to read the correct values of both bytes of the Status Register.
Deasserting the CS pin will terminate the Read Status Register operation and put the SO pin into a high-imped-
ance state. The CS pin can be deasserted at any time and does not require that a full byte of data be read.
Notes: 1. Only bit 7 of Status Register Byte 1 will be modified when using the Write Status Register Byte 1 command.
2. R/W = Readable and writeable
R = Readable only
Table 11-1. Status Register Format – Byte 1
Bit (1) Name Type (2) Description
7 SPRL Sector Protection Registers Locked R/W
0 Sector Protection Registers are unlocked (default)
1 Sector Protection Registers are locked
6 RES Reserved for future use R 0 Reserved for future use
5 EPE Erase/Program Error R
0 Erase or program operation was successful
1 Erase or program error detected
4 WPP Write Protect (WP) Pin Status R
0 WP is asserted
1 WP is deasserted
3:2 SWP Software Protection Status R
00
All sectors are software unprotected (all Sector
Protection Registers are 0)
01
Some sectors are software protected. Read
individual Sector Protection Registers to determine
which sectors are protected
10 Reserved for future use
11
All sectors are software protected (all Sector
Protection Registers are 1 – default)
1 WEL Write Enable Latch Status R
0 Device is not write enabled (default)
1 Device is write enabled
0 RDY/BSY Ready/Busy Status R
0 Device is ready
1 Device is busy with an internal operation