MC68HC908KX2 MOTOROLA [Motorola, Inc], MC68HC908KX2 Datasheet - Page 156

• Manufacturer Part Number: MC68HC908KX2
• Description: Microcontrollers
• Manufacturer: MOTOROLA [Motorola, Inc]

Input/Output (I/O) Ports
10.4.2 Data Direction Register B
Technical Data
156
NOTE:
Address: $0005
TxD — SCI Transmit Data Output Bit
AD3–AD0 — Analog-to-Digital Input Bits
Data direction register B (DDRB) determines whether each port B pin is
an input or an output. Writing a logic 1 to a DDRB bit enables the output
buffer for the corresponding port B pin; a logic 0 disables the output
buffer.
DDRB7–DDRB0 — Data Direction Register B Bits
Avoid glitches on port B pins by writing to the port B data register before
changing data direction register B bits from 0 to 1.
Reset:
Read:
Write:
The PTB0/TxD pin is the transmit data output for the SCI module.
When the enable SCI bit, ENSCI, is clear, the SCI module is
disabled, and the PTB0/TxD pin is available for general-purpose I/O.
See
AD3–AD0 are pins used for the input channels to the analog-to-digital
converter (ADC) module. The channel select bits in the ADC status
and control register define which port B pin will be used as an ADC
input and overrides any control from the port I/O logic by forcing that
pin as the input to the analog circuitry. See
Digital Converter
These read/write bits control port B data direction. Reset clears
DDRB7–DDRB0, configuring all port B pins as inputs.
1 = Corresponding port B pin configured as output
0 = Corresponding port B pin configured as input
Section 14. Serial Communications Interface Module
DDRB7
Bit 7
0
Figure 10-7. Data Direction Register B (DDRB)
Input/Output (I/O) Ports
DDRB6
MC68HC908KX8 • MC68HC908KX2 • MC68HC08KX8 — Rev. 1.0
6
0
(ADC).
DDRB5
5
0
DDRB4
4
0
DDRB3
3
0
Section 17. Analog-to-
DDRB2
2
0
DDRB1
1
0
MOTOROLA
(SCI).
DDRB0
Bit 0
0