
Quad-SPI interface (QUADSPI)
RM0351
474/1830
DocID024597 Rev 5
17.4.3
QUADSPI Command sequence
The QUADSPI communicates with the Flash memory using commands. Each command
can include 5 phases: instruction, address, alternate byte, dummy, data. Any of these
phases can be configured to be skipped, but at least one of the instruction, address,
alternate byte, or data phase must be present.
nCS falls before the start of each command and rises again after each command finishes.
Figure 60. An example of a read command in quad mode
Instruction phase
During this phase, an 8-bit instruction, configured in INSTRUCTION field of
QUADSPI_CCR[7:0] register, is sent to the Flash memory, specifying the type of operation
to be performed.
Though most Flash memories can receive instructions only one bit at a time from the
IO0/SO signal (single SPI mode), the instruction phase can optionally send 2 bits at a time
(over IO0/IO1 in dual SPI mode) or 4 bits at a time (over IO0/IO1/IO2/IO3 in quad SPI
mode). This can be configured using the IMODE[1:0] field of QUADSPI_CCR[9:8] register.
BK1_IO2
Digital input/output
Bidirectional IO in quad mode, for FLASH 1
BK1_IO3
Digital input/output
Bidirectional IO in quad mode, for FLASH 1
BK2_IO0/SO
Digital input/output
Bidirectional IO in dual/quad modes or serial output
in single mode, for FLASH 2
BK2_IO1/SI
Digital input/output
Bidirectional IO in dual/quad modes or serial input
in single mode, for FLASH 2
BK2_IO2
Digital input/output
Bidirectional IO in quad mode, for FLASH 2
BK2_IO3
Digital input/output
Bidirectional IO in quad mode, for FLASH 2
BK1_nCS
Digital output
Chip select (active low) for FLASH 1. Can also be
used for FLASH 2 if QUADSPI is always used in
dual-flash mode.
BK2_nCS
Digital output
Chip select (active low) for FLASH 2. Can also be
used for FLASH 1 if QUADSPI is always used in
dual-flash mode.
Table 99. QUADSPI pins
Signal name
Signal type
Description
069
Q&6
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,2
,2
,2
,2
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0
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