Before any data can be transferred to or from the external flash memory, the
peripheral needs to be configured.
-
Select the mandatory input/output pins in the following registers:
For which pins to use, see
Pin assignments.
Only the dedicated QSPI pins shall be
used. -
To ensure stable operation, set the GPIO drive strength to high drive. See the
GPIO — General purpose input/output chapter for details on how to configure GPIO drive
strength.
-
Activate the dedicated peripheral setting of the GPIO pin. See
the GPIO — General purpose input/output chapter for details on how to assign pins between
cores, peripherals, or subsystems.
-
Configure the interface towards the external flash memory using IFCONFIG0, IFCONFIG1, and ADDRCONF.
-
Enable the QSPI peripheral and acquire I/O pins using ENABLE.
-
Activate the external flash memory interface using the ACTIVATE task. The READY
event will be generated when the interface has been activated and the external
flash memory is ready for access.
Note:
If the IFCONFIG0 register is configured to
use the quad mode, the external flash device also needs to be set in the quad
mode before any data transfers can take place.
This can be done by sending custom instructions to the external flash device, as
described in Sending custom instructions.