
Quad-SPI interface (QUADSPI)
RM0351
476/1830
DocID024597 Rev 5
In order to assure enough “turn-around” time for changing the data signals from output
mode to input mode, there must be at least one dummy cycle when using dual or quad
mode to receive data from the Flash memory.
Data phase
During the data phase, any number of bytes can be sent to, or received from the Flash
memory.
In indirect and automatic-polling modes, the number of bytes to be sent/received is specified
in the QUADSPI_DLR register.
In indirect write mode the data to be sent to the Flash memory must be written to the
QUADSPI_DR register, while in indirect read mode the data received from the Flash
memory is obtained by reading from the QUADSPI_DR register.
In memory-mapped mode, the data which is read is sent back directly over the AHB to the
Cortex or to a DMA.
The data phase can send/receive 1 bit at a time (over SO/SI in single SPI mode), 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 ABMODE[1:0] field of QUADSPI_CCR[15:14]
register.
When DMODE = 00, the data phase is skipped, and the command sequence finishes
immediately by raising nCS. This configuration must only be used in only indirect write
mode.
17.4.4 QUADSPI
signal
interface protocol modes
Single SPI mode
Legacy SPI mode allows just a single bit to be sent/received serially. In this mode, data is
sent to the Flash memory over the SO signal (whose I/O shared with IO0). Data received
from the Flash memory arrives via SI (whose I/O shared with IO1).
The different phases can each be configured separately to use this single bit mode by
setting the IMODE/ADMODE/ABMODE/DMODE fields (in QUADSPI_CCR) to 01.
In each phase which is configured in single mode:
•
IO0 (SO) is in output mode
•
IO1 (SI) is in input mode (high impedance)
•
IO2 is in output mode and forced to ‘0’ (to deactivate the “write protect” function)
•
IO3 is in output mode and forced to ‘1’ (to deactivate the “hold” function)
This is the case even for the dummy phase if DMODE = 01.
Dual SPI mode
In dual SPI mode, two bits are sent/received simultaneously over the IO0/IO1 signals.
The different phases can each be configured separately to use dual SPI mode by setting the
IMODE/ADMODE/ABMODE/DMODE fields of QUADSPI_CCR register to 10.