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1.8 Enhanced Synchronous Serial Interface 0 (ESSI0)
Two synchronous serial interfaces (ESSI0 and ESSI1) provide a full-duplex serial port for serial communication
with a variety of serial devices, including one or more industry-standard codecs, other DSPs, microprocessors, and
peripherals that implement the Freescale serial peripheral interface (SPI).
Signal Name
Type
SC00
Input or Output
PC0
Input or Output
SC01
Input/Output
PC1
Input or Output
SC02
Input/Output
PC2
Input or Output
SCK0
Input/Output
PC3
Input or Output
SRD0
Input
PC4
Input or Output
Freescale Semiconductor
Table 1-12.
Enhanced Synchronous Serial Interface 0
State During
1,2
Reset
Ignored Input
Serial Control 0—For asynchronous mode, this signal is used for the receive
clock I/O (Schmitt-trigger input). For synchronous mode, this signal is used
either for transmitter 1 output or for serial I/O flag 0.
Port C 0—The default configuration following reset is GPIO input PC0. When
configured as PC0, signal direction is controlled through the Port C Direction
Register. The signal can be configured as ESSI signal SC00 through the Port C
Control Register.
Ignored Input
Serial Control 1—For asynchronous mode, this signal is the receiver frame
sync I/O. For synchronous mode, this signal is used either for transmitter 2
output or for serial I/O flag 1.
Port C 1—The default configuration following reset is GPIO input PC1. When
configured as PC1, signal direction is controlled through the Port C Direction
Register. The signal can be configured as an ESSI signal SC01 through the Port
C Control Register.
Ignored Input
Serial Control Signal 2—The frame sync for both the transmitter and receiver
in synchronous mode, and for the transmitter only in asynchronous mode. When
configured as an output, this signal is the internally generated frame sync signal.
When configured as an input, this signal receives an external frame sync signal
for the transmitter (and the receiver in synchronous operation).
Port C 2—The default configuration following reset is GPIO input PC2. When
configured as PC2, signal direction is controlled through the Port C Direction
Register. The signal can be configured as an ESSI signal SC02 through the Port
C Control Register.
Ignored Input
Serial Clock—Provides the serial bit rate clock for the ESSI. The SCK0 is a
clock input or output, used by both the transmitter and receiver in synchronous
modes or by the transmitter in asynchronous modes.
Although an external serial clock can be independent of and asynchronous to
the DSP system clock, it must exceed the minimum clock cycle time of 6T (that
is, the system clock frequency must be at least three times the external ESSI
clock frequency). The ESSI needs at least three DSP phases inside each half of
the serial clock.
Port C 3—The default configuration following reset is GPIO input PC3. When
configured as PC3, signal direction is controlled through the Port C Direction
Register. The signal can be configured as an ESSI signal SCK0 through the Port
C Control Register.
Ignored Input
Serial Receive Data—Receives serial data and transfers the data to the ESSI
Receive Shift Register. SRD0 is an input when data is received.
Port C 4—The default configuration following reset is GPIO input PC4. When
configured as PC4, signal direction is controlled through the Port C Direction
Register. The signal can be configured as an ESSI signal SRD0 through the
Port C Control Register.
DSP56311 Technical Data, Rev. 8
Enhanced Synchronous Serial Interface 0 (ESSI0)
Signal Description
1-11
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