AT26F004-SSU ATMEL [ATMEL Corporation], AT26F004-SSU Datasheet - Page 21

• Manufacturer Part Number: AT26F004-SSU
• Description: 4-megabit 2.7-volt Only Serial Firmware DataFlash Memory
• Manufacturer: ATMEL [ATMEL Corporation]

10.1.6
3588A–DFLSH–10/05
RDY/BSY Bit
If the WEL bit is in the logical “1” state, it will not be reset to a logical “0” if an operation aborts
due to an incomplete or unrecognized opcode being clocked into the device before the CS pin is
deasserted. In order for the WEL bit to be reset when an operation aborts prematurely, the entire
opcode for a program, erase, Protect Sector, Unprotect Sector, or Write Status Register com-
mand must have been clocked into the device.
The RDY/BSY bit is used to determine whether or not an internal operation, such as a program
or erase, is in progress. To poll the RDY/BSY bit to detect the completion of a program or erase
cycle, new Status Register data must be continually clocked out of the device until the state of
the RDY/BSY bit changes from a logical “1” to a logical “0”.
Figure 10-1. Read Status Register
• Block Erase operation completes successfully or aborts
• Chip Erase operation completes successfully or aborts
SCK
SO
CS
SI
HIGH-IMPEDANCE
MSB
0
0
0
1
0
2
OPCODE
0
3
0
4
1
5
0
6
1
7
MSB
D
STATUS REGISTER DATA
8
D
9
D
10 11
D
D
12
D
13 14
D
D
15 16
MSB
D
STATUS REGISTER DATA
D
17
D
18
D
19
D
20
D
21 22
D
AT26F004
D
23 24
MSB
D
D
21