Datasheet
Table Of Contents
- List of Sections
- Table of Contents
- General Description
- Central Processing Unit (CPU)
- Pinout and Signal Description
- System Configuration
- Registers
- Operating Modes
- Resource Mapping
- Bus Control and Input/Output
- Resets and Interrupts
- Voltage Regulator (VREG)
- Flash EEPROM 256K
- EEPROM 4K
- Port Integration Module
- Clocks and Reset Generator (CRG)
- Pulse Width Modulator (PWM)
- Enhanced Capture Timer (ECT)
- Serial Communications Interface (SCI)
- Serial Peripheral Interface (SPI)
- Inter-IC Bus (IIC)
- MSCAN
- Analog to Digital Converter
- Byte Data Link Controller Module
- Contents
- Overview
- Features
- Block Diagram
- Register Map
- Functional Description
- Register Descriptions
- External Pin Descriptions
- Reset Initialization/Basic Operation
- Transmitting A Message
- Receiving A Message
- Transmitting An In-Frame Response (IFR)
- Receiving An In-Frame Response (IFR)
- Special BDLC Operations
- Modes of Operation
- Interrupt Operation
- Low Power Options
- Background Debug Module (BDM)
- Breakpoint (BKP) Module
- Revision History
- Glossary
- Literature Updates

Bus Control and Input/Output
MC9S12DP256 — Revision 1.1
Bus Control and Input/Output
Port A bits 7 through 0 are associated with address lines A15 through
A8 respectively and data lines D15/D7 through D8/D0 respectively.
When this port is not used for external addresses such as in
single-chip mode, these pins can be used as general purpose I/O.
Data Direction Register A (DDRA) determines the primary direction of
each pin. DDRA also determines the source of data for a read of
PORTA.
This register is not in the on-chip map in expanded and peripheral
modes.
CAUTION:
To ensure that you read the value present on the PORTA pins, always
wait at least two cycles after writing to the DDRA register before
reading from the PORTA register.
Read and write: anytime (provided this register is in the map).
PORTA — Port A Register
Address Offset: $0000
Bit 7 654321Bit 0
Single Chip
BIT 7 654321BIT 0
Reset: Unaffected by reset
Expanded
& Periph:
ADDR15/
DATA15
ADDR14/
DATA14
ADDR13/
DATA13
ADDR12/
DATA12
ADDR11/
DATA11
ADDR10/
DATA10
ADDR9/
DATA9
ADDR8/
DATA8
Expanded
narrow
ADDR15/
DATA15/
DATA7
ADDR14/
DATA14/
DATA6
ADDR13/
DATA13/
DATA5
ADDR12/
DATA12/
DATA4
ADDR11/
DATA11/
DATA3
ADDR10/
DATA10/
DATA2
ADDR9/
DATA9/
DATA1
ADDR8/
DATA8/
DATA0
Freescale Semiconductor, I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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