PXD20RM Datasheet, PDF (1239/1628 Pages) Freescale Semiconductor, Inc – PXD20 Microcontroller

Valid address range accessible in the QSPI_ARDBn range depends on the number of valid buffer entries
available in the RX Buffer.
• Example 1, RX Buffer filled completely with 32 words: In this case the address range for valid read
access extends from QSPI_ARDB0 to QSPI_ARDB31.
• Example 2, RX Buffer filled with 5 valid words, RX Buffer fill level QSPI_RBSR[RDBFL] is 5.
In this case an access to QSPI_ARDB4 provides the last valid entry.
35.5 Functional Description
35.5.1 Serial Flash Access Schemes
The Quad Serial Peripheral Interface (QuadSPI) block acts as an interface to one single or two external
serial flash devices, each with up to 4 bidirectional data lines. Depending from the serial flash devices
attached to the QuadSPI module the following access schemes are possible:
Table 35-27. Access Schemes for Serial Flash Data Access
Access Scheme
One Flash Device
on Port A
One Flash Device
on Port B
Two identical
Flash Devices
connected on
Port A and Port B
Individual Flash Mode: Access to Flash A
Yes
N/a
Yes
Individual Flash Mode: Access to Flash B
N/a
Yes
Yes
Parallel Flash Mode: Read from Flash A and Flash B
N/a
N/a
Yes
NOTE
If two flash devices are accessed in Parallel Flash Mode they are accessed
with identical control signals. Special alignment on per-flash basis is not
possible. It is within the responsibility of the application to ensure that the
identical signals are applicable to both flash devices.
In parallel Flash Mode both external serial flash devices appear logically as
one single memory doubled in size w.r.t. one individual flash device.
If two different flash devices are attached they can be operated only in
Individual Flash Mode.
In the Parallel Flash Mode only data read commands are supported. Any
other IP Command will result in an error condition signalled by the assertion
of the QSPI_SFMFR[IUEF] flag and any other AHB Command will result
in the assertion of the QSPI_SFMFR[ABCEF] flag.
In the Individual Flash Mode all supported commands are available.
Unless explicitly noted all the following descriptions relate to the Individual Flash Mode.
Freescale Semiconductor
PXD20 Microcontroller Reference Manual, Rev. 1
Preliminary—Subject to Change Without Notice
35-29