Freescale Semiconductor MPC5565, Reference Manual

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Deserial Serial Peripheral Interface (DSPI)
MPC5565 Microcontroller Reference Manual, Rev. 1.0
19-42 Freescale Semiconductor
Table 19-18 lists the four transfer initiation conditions.
19.4.4.5.1 Continuous Control
For continuous control, the initiation of a transfer is based on the baud rate at which data is transferred
between the DSPI and the external device. The baud rate is set in the DSPI
x _CTAR selected by the
DSICTAS field in the DSPI x _DSICR. A new DSI frame shifts out when the previous transfer cycle has
completed and the delay after transfer (t
DT
) has elapsed.
19.4.4.5.2 Change In Data Control
For change in data control, a transfer is initiated when the data to be serialized has changed since the
transfer of the last DSI frame. A copy of the previously transferred DSI data is stored in the
DSPI
x _COMPR. When the data in the DSPI x _SDR or the DSPI x _ASDR is different from the data in the
DSPI x _COMPR, a new DSI frame is transmitted. The TXSS bit in the DSPI x _DSICR selects which
register the DSPI x _COMPR is compared to. The MTRIG output signal is asserted every time a change in
data is detected.
19.4.4.5.3 Triggered Control
For triggered control, initiation of a transfer is controlled by the internal hardware trigger signal ( ht ). The
TPOL bit in the DSPI x _DSICR selects the active edge of ht . For ht to have any affect, the TRRE bit in the
DSPI x _DSICR must be set.
19.4.4.5.4 Triggered or Change In Data Control
For triggered or change in data control, initiation of a transfer is controlled by the ht signal or by the
detection of a change in data to be serialized.
19.4.4.6 DSPI Connections to eTPUA, eMIOS and SIU
The three DSPI blocks connect to the input and output channels of the eTPUs and the eMIOS. The MCU
connects to eTPUA, eMIOS, and SIU. Some of the DSPI outputs connect to the external interrupt input
multiplexing subblock in the SIU. Refer to
Section 6.4.3, “External Interrupt ,” and Section 18.4.3.4,
“External Trigger Event Detection ,” for details on how the DSPI deserialized outputs can be used to trigger
external interrupt requests and Section 17.3.2, “Output and Input Channel Signals ” for a discussion on
eTPU connections.
Table 19-18. DSI Data Transfer Initiation Control
DSPI x _DSICR Bits
Type of Transfer Initiation Control
TRRE CID
0 0 Continuous
0 1 Change in data
1 0 Triggered
1 1 Triggered or change in data