Rainbow Electronics AT45DB011D - Manual (Page 7)

7
3639J–DFLASH–11/2012
AT45DB011D
operation. Following the don’t care bytes, additional pulses on SCK result in data being output
on the SO (serial output) pin. The CS pin must remain low during the loading of the opcode, the
address bytes, the don’t care bytes, and the reading of data. When the end of a page in main
memory is reached, the device will continue reading back at the beginning of the same page. A
low-to-high transition on the CS pin will terminate the read operation and tri-state the output pin
(SO). The maximum SCK frequency allowable for the Main Memory Page Read is defined by the
f
SCK
specification. The Main Memory Page Read bypasses the data buffer and leaves the con-
tents of the buffer unchanged.
6.5 Buffer Read
The SRAM data buffer can be accessed independently from the main memory array, and utiliz-
ing the Buffer Read Command allows data to be sequentially read directly from the buffer. Two
opcodes, D4H or D1H, can be used for the Buffer Read Command. The use of each opcode
depends on the maximum SCK frequency that will be used to read data from the buffer. The
D4H opcode can be used at any SCK frequency up to the maximum specified by f
CAR1
. The D1H
opcode can be used for lower frequency read operations up to the maximum specified by f
CAR2
.
To perform a buffer read from the DataFlash standard buffer (264-bytes), the opcode must be
clocked into the device followed by three address bytes comprised of 15 don’t care bits and
nine buffer address bits (BFA8 - BFA0). To perform a buffer read from the binary buffer (256-
bytes), the opcode must be clocked into the device followed by three address bytes comprised
of 16 don’t care bits and eight buffer address bits (BFA7 - BFA0). Following the address bytes,
one don’t care byte must be clocked in to initialize the read operation. The CS pin must remain
low during the loading of the opcode, the address bytes, the don’t care bytes, and the reading of
data. When the end of a buffer is reached, the device will continue reading back at the beginning
of the buffer. A low-to-high transition on the CS pin will terminate the read operation and tri-state
the output pin (SO).
7. Program and Erase Commands
7.1 Buffer Write
Data can be clocked in from the input pin (SI) into the buffer. To load data into the DataFlash
standard buffer (264-bytes), a 1-byte opcode, 84H, must be clocked into the device followed by
three address bytes comprised of 15 don’t care bits and 9 buffer address bits (BFA8 - BFA0).
The nine buffer address bits specify the first byte in the buffer to be written. To load data into the
binary buffers (256-bytes each), a 1-byte opcode, 84H, must be clocked into the device followed
by three address bytes comprised of 16 don’t care bits and eight buffer address bits (BFA7 -
BFA0). The eight buffer address bits specify the first byte in the buffer to be written. After the last
address byte has been clocked into the device, data can then be clocked in on subsequent clock
cycles. 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.
7.2 Buffer to Main Memory Page Program with Built-in Erase
Data written into the buffer can be programmed into the main memory. A 1-byte opcode, 83H,
must be clocked into the device. For the DataFlash standard page size (264-bytes), the opcode
must be followed by three address bytes consist of five don’t care bits, nine page address bits
(PA8 - PA0) that specify the page in the main memory to be written and nine don’t care bits. To
perform a buffer to main memory page program with built-in erase for the binary page size (256-