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AT45DB081A Datasheet(PDF) 5 Page - ATMEL Corporation |
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AT45DB081A Datasheet(HTML) 5 Page - ATMEL Corporation |
5 / 28 page AT45DB081A 5 Ready/Busy status is indicated using bit 7 of the status reg- ister. If bit 7 is a 1, then the device is not busy and is ready to accept the next command. If bit 7 is a 0, then the device is in a busy state. The user can continuously poll bit 7 of the status register by stopping SCK once bit 7 has been output. The status of bit 7 will continue to be output on the SO pin, and once the device is no longer busy, the state of SO will change from 0 to 1. There are eight operations which can cause the device to be in a busy state: Main Memory Page to Buffer Transfer, Main Memory Page to Buffer Compare, Buffer to Main Memory Page Program with Built-in Erase, Buffer to Main Memory Page Program without Built-in Erase, Page Erase, Block Erase, Main Memory Page Pro- gram, and Auto Page Rewrite. The result of the most recent Main Memory Page to Buffer Compare operation is indicated using bit 6 of the status register. If bit 6 is a 0, then the data in the main memory page matches the data in the buffer. If bit 6 is a 1, then at least one bit of the data in the main memory page does not match the data in the buffer. The device density is indicated using bits 5, 4, and 3 of the status register. For the AT45DB081A, the three bits are 1, 0 and 0. The decimal value of these three binary bits does not equate to the device density; the three bits represent a combinational code relating to differing densities of Serial DataFlash devices, allowing a total of eight different density configurations. Program and Erase Commands BUFFER WRITE: Data can be shifted in from the SI pin into either buffer 1 or buffer 2. To load data into either buffer, an 8-bit opcode, 84H for buffer 1 or 87H for buffer 2, must be followed by 15 don't care bits and nine address bits (BFA8-BFA0). The nine address bits specify the first byte in the buffer to be written. The data is entered follow- ing the address bits. If the end of the data buffer is reached, the device will wrap around back to the beginning of the buffer. Data will continue to be loaded into the buffer until a low-to-high transition is detected on the CS pin. BUFFER TO MAIN MEMORY PAGE PROGRAM WITH BUILT-IN ERASE: Data written into either buffer 1 or buffer 2 can be programmed into the main memory. To start the operation, an 8-bit opcode, 83H for buffer 1 or 86H for buffer 2, must be followed by the three reserved bits, 12 address bits (PA11-PA0) that specify the page in the main memory to be written, and nine additional don't care bits. When a low-to-high transition occurs 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 the specified page in the main memory. Both the erase and the programming of the page are internally self-timed and should take place in a maximum time of t EP. During this time, the status register will indicate that the part is busy. BUFFER TO MAIN MEMORY PAGE PROGRAM WITH- OUT BUILT-IN ERASE: A previously erased page within main memory can be programmed with the contents of either buffer 1 or buffer 2. To start the operation, an 8-bit opcode, 88H for buffer 1 or 89H for buffer 2, must be followed by the three reserved bits, 12 address bits (PA11- PA0) that specify the page in the main memory to be writ- ten, and nine additional don’t care bits. When a low-to-high transition occurs on the CS pin, the part will program the data stored in the buffer into the specified page in the main memory. It is necessary that the page in main memory that is being programmed has been previously erased. The pro- gramming of the page is internally self-timed and should take place in a maximum time of tP. During this time, the status register will indicate that the part is busy. PAGE ERASE: The optional Page Erase command can be used to individually erase any page in the main memory array allowing the Buffer to Main Memory Page Program without Built-in Erase command to be utilized at a later time. To perform a Page Erase, an opcode of 81H must be loaded into the device, followed by three reserved bits, 12 address bits (PA11-PA0), and nine don’t care bits. The nine address bits are used to specify which page of the memory array is to be erased. When a low-to-high transi- tion occurs on the CS pin, the part will erase the selected page to 1s. The erase operation is internally self-timed and should take place in a maximum time of tPE. During this time, the status register will indicate that the part is busy. BLOCK ERASE: A block of eight pages can be erased at one time allowing the Buffer to Main Memory Page Pro- gram without Built-in Erase command to be utilized to reduce programming times when writing large amounts of data to the device. To perform a Block Erase, an opcode of 50H must be loaded into the device, followed by three reserved bits, nine address bits (PA11-PA3), and 12 don’t care bits. The nine address bits are used to specify which block of eight pages is to be erased. When a low-to-high transition occurs on the CS pin, the part will erase the selected block of eight pages to 1s. The erase operation is internally self-timed and should take place in a maximum time of tBE. During this time, the status register will indicate that the part is busy. Status Register Format Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 RDY/BUSY COMP 100 X X X |
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