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DMA Serial Peripheral Interface (DSPI)
31-30
Freescale Semiconductor
Figure 31-16. DSPI Transfer Timing Diagram (MTFE = 0, CPHA = 1, FMSZ = 8)
The master initiates the transfer by asserting the DSPI_PCS
n
signal to the slave. After the t
CSC
delay has
elapsed, the master generates the first DSPI_SCK edge and places valid data on the master DSPI_SOUT
pin. The slave responds to the first DSPI_SCK edge by placing its first data bit on its slave DSPI_SOUT
pin.
At the second edge of the DSPI_SCK, the master and slave sample their DSPI_SIN pins. For the rest of
the frame, the master and the slave change the data on their DSPI_SOUT pins on the odd-numbered clock
edges and sample their DSPI_SIN pins on the even-numbered clock edges. After the last clock edge
occurs,1 a delay of t
ASC
is inserted before the master negates the DSPI_PCS
n
signal. A delay of t
DT
is
inserted before a new frame transfer can be initiated by the master.
If DSPI_CTAR
n
[CPHA] is set:
•
At the last serial clock edge (edge 16 of
— Master’s EOQF and TCF are set
— Slave’s TCF is set
— Master’s and slave’s RXCTR counters are updated
31.4.4.3
Modified SPI Transfer Format (MTFE = 1, CPHA = 0)
In this modified transfer format, the master and the slave sample later in the DSPI_SCK period than in
classic SPI mode to allow for delays in device pads and board traces. These delays become a more
significant fraction of the DSPI_SCK period as the DSPI_SCK period decreases with increasing baud
rates.
Slave (CPHA = 1): TCF is set and RXCTR counter is updated at
last DSPI_SCK edge of frame (edge 16)
DSPI_SCK
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15
(CPOL = 0)
DSPI_PCS
n
/SS
t
ASC
DSPI_SCK
(CPOL = 1)
Master and Slave
Sample
Master DSPI_SOUT/
Slave DSPI_SIN
Master DSPI_SIN/
Slave DSPI_SOUT
Bit 6
Bit 1
Bit 5
Bit 2
Bit 4
Bit 3
Bit 3
Bit 4
Bit 2
Bit 5
Bit 1
Bit 6
LSB
MSB
MSB
LSB
t
DT
t
CSC
MSB First (LSBFE = 0):
LSB First (LSBFE = 1):
t
CSC
= PCS to SCK delay.
t
ASC
= After SCK delay.
t
DT
= Delay after transfer (minimum CS negation time).
Master (CPHA = 1): TCF and EOQF are set and RXCTR counter
is updated at last DSPI_SCK edge of frame (edge 16)
16
Summary of Contents for MCF54455
Page 33: ...xxviii Freescale Semiconductor ...
Page 67: ...Freescale Semiconductor 1 ...
Page 125: ...Freescale Semiconductor 1 ...
Page 145: ...Enhanced Multiply Accumulate Unit EMAC 5 21 Freescale Semiconductor ...
Page 173: ...Cache 6 28 Freescale Semiconductor ...
Page 179: ...Static RAM SRAM 7 6 Freescale Semiconductor ...
Page 207: ...Power Management 9 16 Freescale Semiconductor ...
Page 323: ...Reset Controller Module 13 8 Freescale Semiconductor ...
Page 389: ...Pin Multiplexing and Control 16 44 Freescale Semiconductor ...
Page 575: ...PCI Bus Controller 22 58 Freescale Semiconductor ...
Page 600: ...Advanced Technology Attachment ATA Freescale Semiconductor 23 25 ...
Page 601: ...Freescale Semiconductor 1 ...
Page 842: ...I2 C Interface Freescale Semiconductor 33 16 ...
Page 843: ...Freescale Semiconductor 1 ...
Page 921: ...Revision History A 6 Freescale Semiconductor ...