AT26DF041-MU ATMEL [ATMEL Corporation], AT26DF041-MU Datasheet - Page 5

• Manufacturer Part Number: AT26DF041-MU
• Description: 4-MEGABIT 3.0-VOLT ONLY OR 2.7-VOLT ONLY SERIAL FIRMWARE DATAFLASH-R
• Manufacturer: ATMEL [ATMEL Corporation]

5.2
5.2.1
5.2.2
3495B–DFLSH–8/05
Program and Erase Commands
Byte Program
Page Program
and SCK is being toggled) starting again with bit 7. The data in the status register is constantly
updated, so each repeating sequence will output new data.
Table 5-1.
Ready/Busy status is indicated using bit 0 of the status register. If bit 0 is a 0, then the device
is not busy and is ready to accept the next command. If bit 0 is a 1, then the device is in a busy
state. The user can continuously poll bit 0 of the status register by stopping SCK at a low level
once bit 0 has been output. The status of bit 0 will continue to be output on the SO pin, and
once the device is no longer busy, the state of SO will change from 1 to 0. There are five oper-
ations which can cause the device to be in a busy state: Page Erase, Block Erase, Byte
Program, Page Program, and Page Program with Auto-Erase.
The device density is indicated using bits 5, 4, 3 and 2 of the status register. For the
AT26DF041, the four bits are 0, 1, 1 and 1. The decimal value of these four binary bits does
not equate to the device density; the four bits represent a combinational code relating to differ-
ing densities of Serial DataFlash devices, allowing a total of 16 different density
configurations.
Bits 7, 6, and 1 of the status register will contain undefined data.
The Byte Program command can be used to program a single byte of data into a previously
erased memory location. An erased memory location is one that has all eight bits set to the
logical “1” state (a byte value of FFH).
The perform a Byte Program operation, an opcode of 02H must be clocked into the device fol-
lowed by the 24-bit address sequence denoting which byte location to program. Since the
upper address limit of the device is 07FFFFh, address bits A23 - A19 are ignored. After all
address bits have been shifted in, the device will take the one byte of data from the SI pin and
store it in the internal buffer. If more than one byte of data is clocked in, then only the last byte
of data sent will be stored in the buffer.
When the CS pin is deasserted (low-to-high transition), the device will take the one byte stored
in the internal buffer and program it into the main memory array at the location specified by
A18 - A0. The programming of the byte is internally self-timed and should take place in a max-
imum time of t
An entire previously erased page in the main memory can be programmed by using the Page
Program command. Data is first shifted into the internal buffer and then programmed into the
specified page in main memory. To start the operation, an opcode of 11H must be clocked into
the device followed by the 24-bit address sequence. Address bits A23 - A19 are ignored since
the upper address limit of the device is 07FFFFh. After all address bits have been shifted in,
the device will take data from the SI pin and store it in the buffer starting at the first byte loca-
tion specified by A7 - A0. If the end of the buffer is reached, the device will wrap around back
to the beginning of the buffer. When there is a low-to-high transition on the CS pin, the device
will program the data stored in the buffer into the specified page in the main memory. It is nec-
Bit 7
X
BP
Status Register Format
. During this time, the status register will indicate that the device is busy.
Bit 6
X
Bit 5
0
Bit 4
1
Bit 3
1
Bit 2
1
AT26DF041
Bit 1
X
RDY/BUSY
Bit 0
5