W25M02GV
8.2.23 Fast Read Dual I/O (BBh)
The Fast Read Dual I/O (BBh) instruction allows for improved random access while maintaining two IO
pins, IO0 and IO1. It is similar to the Fast Read Dual Output (3Bh) instruction but with the capability to input
the Column Address or the dummy clocks two bits per clock. This reduced instruction overhead may allow
for code execution (XIP) directly from the Dual SPI in some applications.
The Fast Read Quad Output instruction sequence is shown in Figure 26a & 26b. When BUF=1, the device
is in the Buffer Read Mode. The data output sequence will start from the Data Buffer location specified by
the 16-bit Column Address and continue to the end of the Data Buffer. Once the last byte of data is output,
the output pin will become Hi-Z state. When BUF=0, the device is in the Continuous Read Mode, the data
output sequence will start from the first byte of the Data Buffer and increment to the next higher address.
When the end of the Data Buffer is reached, the data of the first byte of next memory page will be
following and continues through the entire memory array. This allows using a single Read instruction to
read out the entire memory array and is also compatible to Winbond’s SpiFlash NOR flash memory
command sequence.
Figure 26a. Fast Read Dual I/O Instruction (Buffer Read Mode, BUF=1)
Figure 26b. Fast Read Dual I/O Instruction (Continuous Read Mode, BUF=0)
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