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5.1
INTRODUCTION
The DSP56309 provides thirty-four bidirectional signals that can be configured as GPIO
signals or as dedicated peripheral signals. No dedicated GPIO signals are provided. All
of these signals are GPIO by default after reset. The control register settings of the
DSP56309Õs peripherals determine whether these signals function as GPIO or as
dedicated peripheral signals. This section describes how signals can function as GPIO.
5.2
PROGRAMMING MODEL
Section 2ÑSignal/Connection Descriptions of this manual documents the special uses
of these signals in detail. There are five groups of these signals. They can be controlled
separately or as groups. The groups include the following signals:
¥ Port B: sixteen GPIO signals (shared with the HI08 signals)
¥ Port C: six GPIO signals (shared with the ESSI0 signals)
¥ Port D: six GPIO signals (shared with the ESSI1 signals)
¥ Port E: three GPIO signals (shared with the SCI signals)
¥ Timers: three GPIO signals (shared with the Triple Timer signals)
5.2.1
Port B Signals and Registers
Each of the 16 Port B signals not used as a HI08 signal can be configured as a GPIO
signal. The GPIO functionality of Port B is controlled by three registers: host control
register (HCR), host port GPIO data register (HDR), and host port GPIO direction
register (HDDR). These registers are documented in Section 6ÑHost Interface (HI08) of
this manual.
5.2.2
Port C Signals and Registers
Each of the six Port C signals not used as an ESSI0 signal can be configured as a GPIO
signal. The GPIO functionality of Port C is controlled by three registers: Port C control
register (PCRC), Port C direction register (PRRC), and Port C data register (PDRC).
These registers are documented in Section 7ÑEnhanced Synchronous Serial Interface
(ESSI) of this manual.
MOTOROLA
DSP56309UM/D
General-Purpose I/O
Introduction
5-3
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