Datasheet

Input/Output Ports (PORTS)
MC68HC908QY/QT Family Data Sheet, Rev. 6
100 Freescale Semiconductor
PTAPUE[5:0] — Port A Input Pullup Enable Bits
These read/write bits are software programmable to enable pullup devices on port A pins.
1 = Corresponding port A pin configured to have internal pull if its DDRA bit is set to 0
0 = Pullup device is disconnected on the corresponding port A pin regardless of the state of its
DDRA bit
Table 12-1 summarizes the operation of the port A pins.
12.3 Port B
Port B is an 8-bit general purpose I/O port. Port B is only available on the MC68HC908QY1,
MC68HC908QY2, and MC68HC908QY4.
12.3.1 Port B Data Register
The port B data register (PTB) contains a data latch for each of the eight port B pins.
PTB[7:0] — Port B Data Bits
These read/write bits are software programmable. Data direction of each port B pin is under the control
of the corresponding bit in data direction register B. Reset has no effect on port B data.
Table 12-1. Port A Pin Functions
PTAPUE
Bit
DDRA
Bit
PTA
Bit
I/O Pin
Mode
Accesses to DDRA Accesses to PTA
Read/Write Read Write
10
X
(1)
1. X = don’t care
Input, V
DD
(2)
2. I/O pin pulled to V
DD
by internal pullup.
DDRA5–DDRA0 Pin
PTA5–PTA0
(3)
3. Writing affects data register, but does not affect input.
00X
Input, Hi-Z
(4)
4. Hi-Z = high impedance
DDRA5–DDRA0 Pin
PTA5–PTA0
(3)
X 1 X Output DDRA5–DDRA0 PTA5–PTA0
PTA5–PTA0
(5)
5. Output does not apply to PTA2
Address:
$0001
Bit 7654321Bit 0
Read:
PTB7 PTB6 PTB5 PTB4 PTB3 PTB2 PTB1 PTB0
Write:
Reset: Unaffected by reset
Figure 12-5. Port B Data Register (PTB)