
9- 18
MC68341 USER’S MANUAL
MOTOROLA
In general, rewriting the same value into a control register does not affect the QSPI
operation with the exception of NEWQP (bits 3–0) in SPCR2. Rewriting the same value to
these bits causes the RAM queue pointer to restart execution at the designated location.
If control bits are to be changed, the CPU should halt the QSPI first. With the exception of
SPCR2, writing a different value into a control register while the QSPI is enabled may
disrupt operation. SPCR2 is buffered, preventing any disruption of the current serial
transfer. After completion of the current serial transfer, the new SPCR2 values become
effective.
9.5.4.1 QSPI CONTROL REGISTER 0 (SPCR0). SPCR0 contains parameters for
configuring the QSPI before it is enabled. Although the CPU can read and write this
register, the QSPM has read-only access.
SPCR0
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13
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9876543210
MSTR WOM
Q
BITS
CPOL
CPHA
SPBR
RESET:
0000000100000100
MSTR—Master/Slave Mode Select
1 = QSPI is system master and can initiate transmission to external SPI devices.
0 = QSPI is a slave device, and only responds to externally generated serial
transfers.
MSTR configures the QSPI for either master or slave mode operation. This bit is cleared
on reset and may only be written by the CPU, not the QSPM.
WOMQ—Wired-OR Mode for QSPI Pins
1 = All QSPI port pins designated as output by QDDR function as open-drain outputs
and can be wire-ORed to other external lines.
0 = Output pins have normal outputs instead of open-drain outputs.
WOMQ allows the QSPI pins to be wire-ORed, regardless of whether they are used as
general-purpose outputs or as QSPI outputs. WOMQ affects the QSPI pins whether the
QSPI is enabled or disabled.
BITS—Bits Per Transfer
In master mode, BITS determines the number of data bits transferred for each serial
transfer in the queue that has the command control bit, BITSE of the QSPI RAM, equal
to one. If BITSE equals zero for a command, 8 bits are transferred for that command
regardless of the value in BITS. Data transfers from 8 to 16 bits are supported. Illegal
(reserved) values all default to 8 bits. BITSE is not used in slave mode. All transfers are
of the length specified by BITS. Table 9-8 shows the number of bits per transfer.
Table 9-8. Bits per Transfer if
Command Control Bit BITSE = 1
Bit 13
Bit 12
Bit 11
Bit 10
Bits per Transfer
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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