Motorola DSP56012 ユーザーズマニュアル
Parallel Host Interface
Introduction
MOTOROLA
DSP56012 User’s Manual
4-3
4.1
INTRODUCTION
The parallel Host Interface (HI) can serve as an 8-bit, bidirectional parallel port or, as
Port B, a set of General Purpose Input/Output (GPIO) signals (see
Port B, a set of General Purpose Input/Output (GPIO) signals (see
). When
configured as the HI, the port provides a convenient connection to another processor.
Port B supports up to fifteen GPIO pins, each pin individually configurable as an
output or an input. This section describes both functions, including examples of how
to configure and use this port.
Port B supports up to fifteen GPIO pins, each pin individually configurable as an
output or an input. This section describes both functions, including examples of how
to configure and use this port.
4.2
PORT B CONFIGURATION
Port B functionality is controlled by three memory-mapped registers (see
• Port B Control register (PBC)
• Port B Data Direction Register (PBDDR)
• Port B Data register (PBD)
Note:
Because reset clears both the PBC and PBDDR registers, the default function of
the fifteen specified pins following reset is GPIO input.
the fifteen specified pins following reset is GPIO input.
Note:
Circuitry connected to the Port B pins may need external pull-ups until the
pins are configured for operation.
pins are configured for operation.
Figure 4-1 Port B Interface
Parallel
Host
Interface
Port B
I/0
(15)
PB0–PB7
PB8
PB9
PB10
PB11
PB12
PB13
PB14
PB8
PB9
PB10
PB11
PB12
PB13
PB14
H0–H7
HOA0
HOA1
HOA2
HR/W
HEN
HOREQ
HACK
HOA0
HOA1
HOA2
HR/W
HEN
HOREQ
HACK
8
8