
DocID024597 Rev 5
477/1830
RM0351
Quad-SPI interface (QUADSPI)
500
In each phase which is configured in dual mode:
•
IO0/IO1 are at high-impedance (input) during the data phase for read operations, and
outputs in all other cases
•
IO2 is in output mode and forced to ‘0’
•
IO3 is in output mode and forced to ‘1’
In the dummy phase when DMODE = 01, IO0/IO1 are always high-impedance.
Quad SPI mode
In quad SPI mode, four bits are sent/received simultaneously over the IO0/IO1/IO2/IO3
signals.
The different phases can each be configured separately to use quad SPI mode by setting
the IMODE/ADMODE/ABMODE/DMODE fields of QUADSPI_CCR register to 11.
In each phase which is configured in quad mode, IO0/IO1/IO2/IO3 are all are at high-
impedance (input) during the data phase for read operations, and outputs in all other cases.
In the dummy phase when DMODE = 11, IO0/IO1/IO2/IO3 are all high-impedance.
IO2 and IO3 are used only in Quad SPI mode. If none of the phases are configured to use
Quad SPI mode, then the pins corresponding to IO2 and IO3 can be used for other functions
even while QUADSPI is active.
SDR mode
By default, the DDRM bit (QUADSPI_CCR[31]) is 0 and the QUADSPI operates in single
data rate (SDR) mode.
In SDR mode, when the QUADSPI is driving the IO0/SO, IO1, IO2, IO3 signals, these
signals transition only with the falling edge of CLK.
When receiving data in SDR mode, the QUADSPI assumes that the Flash memories also
send the data using CLK’s falling edge. By default (when SSHIFT = 0), the signals are
sampled using the following (rising) edge of CLK.
DDR mode
When the DDRM bit (QUADSPI_CCR[31]) is set to 1, the QUADSPI operates in double data
rate (DDR) mode.
In DDR mode, when the QUADSPI is driving the IO0/SO, IO1, IO2, IO3 signals in the
address/alternate-byte/data phases, a bit is sent on each of the falling and rising edges of
CLK.
The instruction phase is not affected by DDRM. The instruction is always sent using CLK’s
falling edge.
When receiving data in DDR mode, the QUADSPI assumes that the Flash memories also
send the data using both rising and falling CLK edges. When DDRM = 1, firmware must
clear SSHIFT bit (QUADSPI_CR[4]). Thus, the signals are sampled one half of a CLK cycle
later (on the following, opposite edge).