Rainbow Electronics AT25F2048 - Manual (Page 10)

10
AT25F2048
2455D–SEEPR–7/04
A single PROGRAM instruction programs 1 to 256 consecutive bytes within a page if it
is not write protected. The starting byte could be anywhere within the page. When the
end of the page is reached, the address will wrap around to the beginning of the same
page. If the data to be programmed are less than a full page, the data of all other bytes
on the same page will remain unchanged. If more than 256 bytes of data are provided,
the address counter will roll over on the same page and the previous data provided will
be replaced. The same byte cannot be reprogrammed without erasing the whole sector
first. The AT25F2048 will automatically return to the write disable state at the completion
of the PROGRAM cycle.
Note: If the device is not write enabled (WREN), the device will ignore the Write instruction and
will return to the standby state, when CS is brought high. A new CS falling edge is
required to re-initiate the serial communication.
SECTOR ERASE (SECTOR ERASE): Before a byte can be reprogrammed, the sector
which contains the byte must be erased. In order to erase the AT25F2048, two separate
instructions must be executed. First, the device must be write enabled via the WREN
instruction. Then the SECTOR ERASE instruction can be executed.
The SECTOR ERASE instruction erases every byte in the selected sector if the sector is
not locked out. Sector address is automatically determined if any address within the sec-
tor is selected. The SECTOR ERASE instruction is internally controlled; it will
autom atically be tim ed to com pletion. During this time, all comm ands will be
ignored, except RDSR instruction. The AT25F2048 will automatically return to the write
disable state at the completion of the SECTOR ERASE cycle.
CHIP ERASE (CHIP ERASE): As an alternative to the SECTOR ERASE, the CHIP
ERASE instruction will erase every byte in all sectors that are not locked out. First, the
device must be write enabled via the WREN instruction. Then the CHIP ERASE instruc-
tion can be executed. The CHIP ERASE instruction is internally controlled; it will
automatically be timed to completion. The CHIP ERASE cycle time typically is 4 sec-
onds. During the internal erase cycle, all instructions will be ignored except RDSR. The
AT25F2048 will automatically return to the write disable state at the completion of the
CHIP ERASE cycle.
Table 6. Address Key
Address AT25F2048
A
N
A
17
- A
0
Dont’ Care Bits A
23
- A
18
Table 7. Sector Addresses
Sector Address AT25F2048 Sector
000000 to 00FFFF Sector 1
010000 to 01FFFF Sector 2
020000 to 02FFFF Sector 3
030000 to 03FFFF Sector 4