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DMA Serial Peripheral Interface (DSPI)
Freescale Semiconductor
31-33
Figure 31-19. Example of Non-Continuous Format (CPHA=1, CONT=0)
When CONT is set and the DSPI_PCS
n
signal for the next transfer the same as for the current transfer,
DSPI_PCS
n
signal remains asserted for the duration of the two transfers. The delay between transfers (t
DT
)
is not inserted between the transfers.
shows the timing diagram for two four-bit transfers with
CPHA and CONT set.
Figure 31-20. Example of Continuous Transfer (CPHA = 1, CONT = 1)
, the period length at the start of the next transfer is the sum of t
ASC
and t
CSC
. It does not
include a half-clock period. The default settings for these provide a total of four system clocks. In many
situations, t
ASC
and t
CSC
must be increased if a full half-clock period is required.
Switching DSPI_CTAR
n
registers between frames while using continuous selection can cause errors in
the transfer. The DSPI_PCS
n
signal must be negated before DSPI_CTAR is switched.
When CONT is set and the DSPI_PCS
n
signals for the next transfer are different from the present transfer,
the DSPI_PCS
n
signals behave as if the CONT bit was cleared.
DSPI_SCK
(CPOL = 0)
DSPI_PCS
n
t
ASC
DSPI_SCK
(CPOL = 1)
Master DSPI_SOUT
t
DT
t
CSC
t
CSC
= PCS to SCK delay.
t
ASC
= After SCK delay.
t
DT
= Delay after transfer (minimum CS negation time).
Master DSPI_SIN
t
CSC
DSPI_SCK
(CPOL = 0)
DSPI_PCS
n
t
ASC
DSPI_SCK
(CPOL = 1)
Master DSPI_SOUT
t
CSC
t
CSC
t
CSC
= PCS to SCK delay.
t
ASC
= After SCK delay.
Master DSPI_SIN
Содержание MCF54455
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Страница 145: ...Enhanced Multiply Accumulate Unit EMAC 5 21 Freescale Semiconductor ...
Страница 173: ...Cache 6 28 Freescale Semiconductor ...
Страница 179: ...Static RAM SRAM 7 6 Freescale Semiconductor ...
Страница 207: ...Power Management 9 16 Freescale Semiconductor ...
Страница 323: ...Reset Controller Module 13 8 Freescale Semiconductor ...
Страница 389: ...Pin Multiplexing and Control 16 44 Freescale Semiconductor ...
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Страница 600: ...Advanced Technology Attachment ATA Freescale Semiconductor 23 25 ...
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Страница 842: ...I2 C Interface Freescale Semiconductor 33 16 ...
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