Queued Serial Multi-Channel Module
MPC561/MPC563 Reference Manual, Rev. 1.2
Freescale Semiconductor
15-35
When the proper number of bits have been transferred, the QSPI stores the working queue pointer value
in CPTQP, increments the working queue pointer, and loads the next data for transfer from transmit RAM.
The command pointed to by the incremented working queue pointer is executed next, unless a new value
has been written to NEWQP. If a new queue pointer value is written while a transfer is in progress, that
transfer is completed normally.
When the CONT bit in a command RAM byte is set, PCS pins are continuously driven to specified states
during and between transfers. If the chip-select pattern changes during or between transfers, the original
pattern is driven until execution of the following transfer begins. When CONT is cleared, the data in
register PORTQS is driven between transfers. The data in PORTQS must match the inactive states of SCK
and any peripheral chip-selects used.
When the QSPI reaches the end of the queue, it sets the SPIF flag. If the SPIFIE bit in SPCR2 is set, an
interrupt request is generated when SPIF is asserted. At this point, the QSPI clears SPE and stops unless
wraparound mode is enabled.
15.6.5.1
Clock Phase and Polarity
In master mode, data transfer is synchronized with the internally-generated serial clock SCK. Control bits,
CPHA and CPOL, in SPCR0, control clock phase and polarity. Combinations of CPHA and CPOL
determine upon which SCK edge to drive outgoing data from the MOSI pin and to latch incoming data
from the MISO pin.
15.6.5.2
Baud Rate Selection
Baud rate is selected by writing a value from two to 255 into the SPBR field in SPCR0. The QSPI uses a
modulus counter to derive the SCK baud rate from the MCU IMB3 clock.
The following expressions apply to the SCK baud rate:
Eqn. 15-1
or
Eqn. 15-2
Giving SPBR a value of zero or one disables the baud rate generator. SCK is disabled and assumes its
inactive state. At reset, the SCK baud rate is initialized to one eighth of the IMB3 clock frequency.
provides some example SCK baud rates with a 40-MHz IMB3 clock.
Table 15-21. Example SCK Frequencies with a 40-MHz IMB3 Clock
Division Ratio
SPBR Value
SCK
Frequency
4
2
10.00 MHz
6
3
6.67 MHz
8
4
5.00 MHz
SCK Baud Rate
f
SYS
2xSPBR
-----------------------
=
SPBR
f
SYS
2xSCK Baud Rate Desired
-----------------------------------------------------------------------
=
Summary of Contents for MPC561
Page 84: ...MPC561 MPC563 Reference Manual Rev 1 2 lxxxiv Freescale Semiconductor...
Page 144: ...Signal Descriptions MPC561 MPC563 Reference Manual Rev 1 2 2 46 Freescale Semiconductor...
Page 206: ...Central Processing Unit MPC561 MPC563 Reference Manual Rev 1 2 3 62 Freescale Semiconductor...
Page 302: ...Reset MPC561 MPC563 Reference Manual Rev 1 2 7 14 Freescale Semiconductor...
Page 854: ...Time Processor Unit 3 MPC561 MPC563 Reference Manual Rev 1 2 19 24 Freescale Semiconductor...
Page 968: ...Development Support MPC561 MPC563 Reference Manual Rev 1 2 23 54 Freescale Semiconductor...
Page 1144: ...Internal Memory Map MPC561 MPC563 Reference Manual Rev 1 2 B 34 Freescale Semiconductor...
Page 1212: ...TPU3 ROM Functions MPC561 MPC563 Reference Manual Rev 1 2 D 60 Freescale Semiconductor...
Page 1216: ...Memory Access Timing MPC561 MPC563 Reference Manual Rev 1 2 E 4 Freescale Semiconductor...