SIGNAL DESCRIPTIONS
2 - 10
DSP56002 PIN DESCRIPTIONS
MOTOROLA
2.2.6
Serial Communication Interface (SCI)
The following signals relate to the SCI. They are introduced briefly here and described in
more detail in
2.2.6.1
Receive Data (RXD)
This input receives byte-oriented data and transfers the data to the SCI receive shift reg-
ister. Input data is sampled on the positive or the negative edge of the receive clock,
depending on how the SCI control register is programmed. RXD can be programmed as
a general-purpose I/O pin (PC0) when it is not being used as an SCI pin, and it is config-
ured as a GPIO input pin during hardware reset.
2.2.6.2
Transmit Data (TXD)
This output transmits serial data from the SCI transmit shift register. Data changes on the
negative edge of the transmit clock. This output is stable on the positive or the negative
edge of the transmit clock, depending on how the SCI control register is programmed.
TXD can be programmed as a general-purpose I/O pin (PC1) when the SCI TXD function
is not being used, and it is configured as a GPIO input pin during hardware reset.
2.2.6.3
SCI Serial Clock (SCLK)
This bidirectional pin provides an input or output clock from which the transmit and/or re-
ceive baud rate is derived in the asynchronous mode, and from which data is transferred
in the synchronous mode. SCLK can be programmed as a general-purpose I/O pin (PC2)
when the SCI SCLK function is not being used, and it is configured as a GPIO input pin
during hardware reset.
2.2.7
Synchronous Serial Interface (SSI)
The SSI signals are presented in the following paragraphs.The SSI operating mode af-
fects the definition and function of SSI control pins SC0, SC1, and SC2. They are
introduced briefly here and are described in more detail in
2.2.7.1
Serial Clock Zero (SC0)
This bidirectional pin’s function is determined by whether the SCLK is in synchronous or
asynchronous mode. In synchronous mode, this pin is used for serial flag I/O. In asynchro-
nous mode, this pin receives clock I/O. SC0 can be programmed as a general-purpose
I/O pin (PC3) when the SSI SC0 function is not being used, and it is configured as a GPIO
input pin during hardware reset.
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For More Information On This Product,
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