MC68HC05K0 Datasheet, PDF (70/154 Pages) Freescale Semiconductor, Inc – HCMOS Microcontroller Unit

Technical Data
Freescale Semiconductor, Inc.
When a port A pin is programmed as an output, reading the port bit
actually reads the value of the data latch and not the voltage on the pin
itself. When a port A pin is programmed as an input, reading the port bit
reads the voltage level on the pin. The data latch can always be written,
regardless of the state of its DDR bit. Table 7-1 summarizes the
operations of the port A pins.
Table 7-1. Port A Pin Functions
Pulldown
Mask
Option
No
No
Control Bits
PDIAx
X
X
DDRAx
0
1
Yes
0
0
Yes
0
1
Yes
1
0
Yes
1
1
X = Don’t care
U = Undefined
I/O Pin Mode
Input, hi-z
Output
Input,
pulldown on
Output
Input, hi-z
Output
Accesses
to PDRA
Read
Write
U PDIA7–PDIA0
U PDIA7–PDIA0
U PDIA7–PDIA0
U PDIA7–PDIA0
U PDIA7–PDIA0
U PDIA7–PDIA0
Accesses
to DDRA
Read/Write
DDRA7–DDRA0
DDRA7–DDRA0
DDRA7–DDRA0
DDRA7–DDRA0
DDRA7–DDRA0
DDRA7–DDRA0
Accesses
to PORTA
Read
Write
Pin
PA0–PA7
PA0–PA7 PA0–PA7
Pin
PA0–PA7
PA0–PA7
Pin
PA0–PA7
PA0–PA7
PA0–PA7
PA0–PA7
7.4 Port B
Port B is a 2-bit, general-purpose, bidirectional I/O port with these
features:
• Programmable pulldown devices (mask option)
• Oscillator output for 3-pin resistor-capacitor (RC) oscillator mask
option
7.4.1 Port B Data Register
The port B data register (PORTB), shown in Figure 7-5, contains a bit
for each of the port B pins. When a port B pin is programmed to be an
output, the state of its data register bit determines the state of the output
pin. When a port B pin is programmed to be an input, reading the port B
Technical Data
MC68HC05K0 • MC68HC05K1 — Rev. 2.0
Parallel Input/Output (I/O)
For More Information On This Product,
Go to: www.freescale.com