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DMA Serial Peripheral Interface (DSPI)
Freescale Semiconductor
31-29
Figure 31-15. DSPI Transfer Timing Diagram (MTFE = 0, CPHA = 0, FMSZ = 8)
The master initiates the transfer by placing its first data bit on the DSPI_SOUT pin and asserting the
appropriate peripheral chip select signals to the slave device. The slave responds by placing its first data
bit on its DSPI_SOUT pin. After the
t
CSC
delay elapses, the master outputs the first edge of DSPI_SCK.
The master and slave devices use this edge to sample the first input data bit on their serial data input
signals. At the second edge of the DSPI_SCK, the master and slave devices place their second data bit on
their serial data output signals. For the rest of the frame, the master and the slave sample their DSPI_SIN
pins on the odd-numbered clock edges and change the data on their DSPI_SOUT pins on the
even-numbered clock edges. After the last clock edge occurs, a delay of t
ASC
is inserted before the master
negates the DSPI_PCS
n
signals. A delay of t
DT
is inserted before a new frame transfer can be initiated by
the master.
If DSPI_CTAR
n
[CPHA] is cleared:
•
At the next to last serial clock edge of the frame (edge 15 of
)
— Master’s TCF and EOQF are set and RXCTR counter is updated
•
At the last serial clock edge of the frame (edge 16 of
)
— Slave’s TCF is set and RXCTR counter is updated
31.4.4.2
Classic SPI Transfer Format (CPHA = 1)
communicates with peripheral SPI slave devices that require
the first DSPI_SCK edge before the first data bit becomes available on the slave DSPI_SOUT pin. In this
format, the master and slave devices change the data on their DSPI_SOUT pins on the odd-numbered
DSPI_SCK edges and sample the data on their DSPI_SIN pins on the even-numbered DSPI_SCK edges.
DSPI_SCK
(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
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 idle time).
Master (CPHA = 0): TCF and EOQF are set and RXCTR counter
is updated at next to last DSPI_SCK edge of frame (edge 15)
Slave (CPHA = 0): TCF is set and RXCTR counter is updated at
last DSPI_SCK edge of frame (edge 16)
1
2
3
4
5
6
7
8
9
10 11 12 13 14
16
15
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 ...