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AT25SL321

DS-25SL321–112H–2020-10

8.8

Read Data (03h)

The Read Data instruction is used to read data out from the memory. The instruction is initiated by driving the CS

pin low and then sending the instruction code 03h, followed by a 24-bit address (A23- A0), onto the SI pin. After

the address is received, the data byte of the addressed memory location is shifted out on the SO pin at the falling

edge of SCK with the most significant bit (MSB) first. The address is automatically incremented to the next higher

address after byte of data is shifted out allowing for a continuous stream of data. This means that the entire

memory can be accessed with a single instruction as long as the clock continues.

The instruction is completed by driving CS high. The Read Data instruction sequence is shown in Figure 8-10. If a

Read Data instruction is issued while an Erase, Program or Write Status Register cycle is in process (BUSY = 1)

the instruction is ignored and does not have any effect on the current cycle. The Read Data instruction allows clock

rates from D.C. to a maximum of fR (see AC Electrical Characteristics).

Figure 8-10. Read Data Instruction

8.9

Fast Read (0Bh)

The Fast Read instruction can operate at the highest possible frequency of FR. The OBh instruction is driven onto

the SI pin, followed by the 24-bit address, and is latched on the rising edge of SCK. The address is then followed

by 8 dummy clocks as shown in Figure 8-11. The dummy clocks allows the internal circuits time to set up the initial

address. During the dummy clocks, the data value on the SO pin is a “don’t care”. Data of each bit shifts out on the

falling edge of SCK.

Figure 8-11. Fast Read Instruction (SPI Mode)

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