PXD20RM Datasheet, PDF (1240/1628 Pages) Freescale Semiconductor, Inc – PXD20 Microcontroller

35.5.2 Modes of Operation
Refer to Section 35.1.3, QuadSPI modes of operation for an overview over the possible operational modes
of the QuadSPI block.
• Normal Mode can be used for write or read accesses to an external serial flash device.
— Serial Flash Write: Data can be programmed into the flash of the serial flash device. Refer to
Section 35.5.3.2, Flash Programming, for further details.
— Serial Flash Read: Read the contents of the serial flash device. Two separate read channels are
available via RX Buffer and AHB Buffer, see Section 35.5.3.3, Flash Read.
• Stop Mode: The mode is used for power management. When a request is made to enter Stop Mode,
the QuadSPI block acknowledges the request and completes the SFM Command in progress, then
the system clocks to the QuadSPI block may be shut off, see Section 35.5.4.1, Stop Mode.
• Module Disable Mode: The mode is used for power management. The clock to the non-memory
mapped logic in the QuadSPI can be stopped while in Module Disable Mode.The module enters
the mode by setting QSPI_MCR[MDIS] or when a request is asserted by an external controller. See
Section 35.5.4.2, Module Disable Mode, for more details.
35.5.3 Normal Mode
This mode is used to allow communication with an external serial flash device. Compared to the standard
SPI protocol, this communication method uses up to 4 bidirectional data lines operating at high data rates.
The communication to the external serial flash device consists of an instruction code and optional address,
mode, dummy and data transfers. All operations to the external serial flash device may use only instruction
codes listed in Section 35.8, Serial Flash Devices.
35.5.3.1 Issuing SFM Commands
Each access to the external device follows the same sequence:
1. The user must provide the required components of a SFM command to the QuadSPI module.
2. From these components the complete transaction is built. The transaction starts and the status bit
QSPI_SFMSR[BUSY] is set.
3. Communication with the external serial flash device is started and the transaction is executed.
4. When the transaction is finished (all transmit- and receive operations with the external serial flash
device are finished) the status bit QSPI_SFMSR[BUSY] is reset. In case of an IP Command the
QSPI_SFMFR[TFF] flag is asserted.
Further details are given in below in Section 35.5.3.2, Flash Programming, and Section 35.5.3.3, Flash
Read.
Note that there are 2 different ways to trigger the processing of SFM Commands in the QuadSPI module.
35.5.3.1.1 IP Commands
For IP Commands the required components need to be written into the following registers:
35-30
PXD20 Microcontroller Reference Manual, Rev. 1
Preliminary—Subject to Change Without Notice
Freescale Semiconductor