mcf5272 Freescale Semiconductor, Inc, mcf5272 Datasheet - Page 347

• Manufacturer Part Number: mcf5272
• Description: Mcf5272 Coldfire Integrated Microprocessor User
• Manufacturer: Freescale Semiconductor, Inc

MOTOROLA
RAM. Each time the end of the queue is reached, QIR[SPIFE] is set. QIR[SPIF] is not
automatically reset. If interrupt driven QSPI service is used, the service routine must clear
QIR[SPIF] to abort the current request. Additional interrupt requests during servicing can
be prevented by clearing QIR[SPIFE].
There are two recommended methods of exiting wraparound mode: clearing
QWR[WREN] or setting QWR[HALT]. Exiting wraparound mode by clearing
QDLYR[SPE] is not recommended because this may abort a serial transfer in progress. The
QSPI sets SPIF, clears QDLYR[SPE], and stops the first time it reaches the end of the queue
after QWR[WREN] is cleared. After QWR[HALT] is set, the QSPI finishes the current
transfer, then stops executing commands. After the QSPI stops, QDLYR[SPE] can be
cleared.
14.5 Programming Model
The programming model for the QSPI consists of six registers. They are the QSPI mode
register (QMR), QSPI delay register (QDLYR), QSPI wrap register (QWR), QSPI interrupt
register (QIR), QSPI address register (QAR), and the QSPI data register (QDR).
There are a total of 80 bytes of memory used for transmit, receive, and control data. This
memory is accessed indirectly using QAR and QDR.
Registers and RAM are written and read by the CPU.
14.5.1 QSPI Mode Register (QMR)
The QMR register, shown in Figure 14-3, determines the basic operating modes of the
QSPI module. Parameters such as clock polarity and phase, baud rate, master mode
operation, and transfer size are determined by this register. The data output high impedance
enable, DOHIE, controls the operation of QSPI_Dout between data transfers. When
DOHIE is cleared, QSPI_Dout is actively driven between transfers. When DOHIE is set,
QSPI_Dout assumes a high impedance state.
Address
Reset
Field
R/W
MSTR DOHIE
15
Because the QSPI does not operate in slave mode, the master
mode enable bit, QMR[MSTR], must be set for the QSPI
module to operate correctly.
Chapter 14. Queued Serial Peripheral Interface (QSPI) Module
14
Figure 14-3. QSPI Mode Register (QMR)
13
BITS
10
0000_0001_0000_0100
NOTE:
CPOL CPHA
MBAR + 0x00A0
9
R/W
8
7
BAUD
Programming Model
14-9
0