Datasheet

Input/Output Ports (PORTS)
MC68HC908QYA/QTA Family Data Sheet, Rev. 3
106 Freescale Semiconductor
12.3.4 Port A Summary Table
The following table summarizes the operation of the port A pins when used as a general-purpose
input/output pins.
12.4 Port B
Port B is an 8-bit special function port that shares two of its pins with the 10-bit ADC (see Chapter 3
Analog-to-Digital Converter (ADC10) Module).
Each port B pin also has a software configurable pullup device if the corresponding port pin is configured
as an input port.
12.4.1 Port B Data Register
The port B data register (PTB) contains a data latch for each of the 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
Bit 76 5 4 3 2 1Bit 0
Read:
PTB7 PTB6 PTB5 PTB4 PTB3 PTB2 PTB1 PTB0
Write:
Reset: Unaffected by reset
Figure 12-5. Port B Data Register (PTB)