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MPC563XM Reference Manual, Rev. 1
Freescale Semiconductor
1083
Preliminary—Subject to Change Without Notice
24.6.9
EQADC Synchronous Serial Interface (SSI) Sub-Block
Figure 24-81. EQADC Synchronous Serial Interface Block Diagram
The EQADC SSI protocol allows for a full duplex, synchronous, serial communication between the
EQADC and a single external device.
shows the different components inside the EQADC
SSI block. The EQADC SSI sub-block on the EQADC is always configured as a master. The EQADC SSI
has four associated port pins:
•
Free running Clock (FCK)
•
Serial Data Select (SDS)
•
Serial Data In (SDI)
•
Serial Data Out (SDO)
The FCK clock signal times the shifting and sampling of the two serial data signals and it is free running
between transmissions, allowing it to be used as the clock for the external device. The SDS signal will be
asserted to indicate the start of a transmission, and negated to indicate the end or the abort of a
transmission. SDI is the master serial data input and SDO the master serial data output.
The EQADC SSI sub-block is enabled by setting the ESSIE field in the
Module Configuration Register (EQADC_MCR)
. When enabled, the EQADC SSI can be optionally
capable of starting serial transmissions. When serial transmissions are disabled (ESSIE set to 0b10), no
data will be transmitted to the external device but FCK will be free-running. This operation mode permits
the control of the timing of the first serial transmission, and can be used to avoid the transmission of data
to an unstable external device, for example, a device that is not fully reset. This mode of operation is
specially important for the reset procedure of an external device that uses the FCK as its main clock.
Master
Slave In
Out
Pad
Interface
SDS
FCK
SDO
SDI
EQADC SSI Control Register
FCK
Clock
System
SkyBlue-Line Interface
Transmit Shift Register
EQADC SSI Control Logic
Receive Shift Register
BR
CFIFO Data
RFIFO Data
EQADC FIFO
Control Unit
Control
MDT
Clock
Divide by: 2, 3, 4,
.. , 15, 16, 17
Baud Clock Generator