10

AT45DB321D [DATASHEET]

3597T–DFLASH–11/2013

5.8

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

are first clocked into buffer 1 or buffer 2 from the input pin (SI), and then programmed into a specified page in the main memory.

To perform a main memory page program through buffer for the standard DataFlash page size (528 bytes), a one-byte opcode,

82H for buffer 1 or 85H for buffer 2, must first be clocked into the device, followed by three address bytes. The address bytes

are comprised of 1 don’t care bit, 13 page address bits, (PA12 - PA0) that select the page in the main memory where data is to

be written, and 10 buffer address bits (BFA9 - 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 (512 bytes), the 82H opcode for buffer 1 or 85H opcode for buffer

2 must be clocked into the device, followed by three address bytes consisting of 2 don’t care bits, 13 page address bits (A21 -

A9) that specify the page in the main memory to be written, and 9 buffer address bits (BFA8 - BFA0) that select 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 them 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 ones, and then

program the data stored in the buffer into that memory page. Both the erase and the programming of the page are internally

indicate that the part is busy.

6.

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 controlled method employs the use of the write protect (WP) pin. The selection of which

sectors 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 determined by checking the status register.

6.1

Software Sector Protection

6.1.1

Enable Sector Protection Command

Sectors specified for protection in the sector protection register can be protected from program and erase operations by issuing

the enable sector protection command. To enable sector protection using the software controlled method, the CS pin must first

be asserted, as it would be with any other command. Once the CS pin has been asserted, the appropriate four-byte command

sequence must be clocked in via the input pin (SI). After the last bit of the command sequence has been clocked in, the CS pin

must be deasserted, after which the sector protection will be enabled.

Table 6-1.

Enable Sector Protection Command

Command

Byte 1

Byte 2

Byte 3

Byte 4

Figure 6-1. Enable Sector Protection

Enable Sector Protection

3DH

2AH

7FH

A9H

Opcode

Byte 1

Opcode

Byte 2

Opcode

Byte 3

Opcode

Byte 4

CS

Each transition

represents 8 bits

SI