AT45DB021D_08 datasheet(11/52 Pages) ATMEL

11 / 52 page

3638F–DFLASH–4/08

AT45DB021D

7.8

Main Memory Page Program Through Buffer

This operation is a combination of the Buffer Write and Buffer to Main Memory Page Program

with Built-in Erase operations. Data is first clocked into the buffer from the input pin (SI) and then

programmed into a specified page in the main memory. To perform a main memory page pro-

gram through buffer for the DataFlash standard page size (264 bytes), a 1-byte opcode, 82H,

must first be clocked into the device, followed by three address bytes. The address bytes are

comprised of 5 don’t care bits, 10 page address bits, (PA9 - PA0) that select the page in the

main memory where data is to be written, and 9 buffer address bits (BFA8 - BFA0) that select

the first byte in the buffer to be written. To perform a main memory page program through buffer

for the binary page size (256 bytes), the opcode 82H must be clocked into the device followed

by three address bytes consisting of 6 don’t care bits, 10 page address bits (A17 - A8) that spec-

ify the page in the main memory to be written, and 8 buffer address bits (BFA7 - BFA0) that

selects the first byte in the buffer to be written. After all address bytes are clocked in, the part will

take data from the input pins and store it in the specified data buffer. 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 part will first erase the selected page in main memory to all 1s

and then program the data stored in the buffer into that memory page. Both the erase and the

programming of the page are internally self-timed and should take place in a maximum time of

EP. During this time, the status register will indicate that the part is busy.

Sector Protection

Two protection methods, hardware and software controlled, are provided for protection against

inadvertent or erroneous program and erase cycles. The software controlled method relies on

the use of software commands to enable and disable sector protection while the hardware con-

trolled method employs the use of the Write Protect (WP) pin. The selection of which sectors

that are to be protected or unprotected against program and erase operations is specified in the

nonvolatile Sector Protection Register. The status of whether or not sector protection has been

enabled or disabled by either the software or the hardware controlled methods can be deter-

mined by checking the Status Register.

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