MC908QY8CDWE Datasheet, PDF (108/232 Pages) Freescale Semiconductor, Inc – Addendum to MC68HC908QB8, rev. 3

Input/Output Ports (PORTS)
12.2.4 Port A Summary Table
The following table summarizes the operation of the port A pins when used as a general-purpose
input/output pins.
Table 12-1. Port A Pin Functions
PTAPUE
Bit
1
0
X
DDRA
Bit
0
0
1
PTA
Bit
X⁽¹⁾
X
X
I/O Pin
Mode
Input, V_DD(2)
Input, Hi-Z⁽⁴⁾
Output
Accesses to DDRA
Read/Write
DDRA5–DDRA0
DDRA5–DDRA0
DDRA5–DDRA0
1. X = don’t care
2. I/O pin pulled to V_DD by internal pullup.
3. Writing affects data register, but does not affect input.
4. Hi-Z = high impedance
5. Output does not apply to PTA2
Accesses to PTA
Read
Write
Pin
PTA5–PTA0⁽³⁾
Pin
PTA5–PTA0⁽³⁾
PTA5–PTA0
PTA5–PTA0⁽⁵⁾
12.3 Port B
Port B is an 8-bit special function port that shares its pins with the 4-channel timer interface module (TIM)
(see Chapter 16 Timer Interface Module (TIM)), the 10-bit ADC (see Chapter 3 Analog-to-Digital
Converter (ADC10) Module), the serial peripheral interface (SPI) module (see Chapter 15 Serial
Peripheral Interface (SPI) Module) and the enhanced serial communications interface (ESCI) module
(see Chapter 13 Enhanced Serial Communications Interface (ESCI) Module).
Each port B pin also has a software configurable pullup device if the corresponding port pin is configured
as an input port.
12.3.1 Port B Data Register
The port B data register (PTB) contains a data latch for each of the port B pins.
Bit 7
6
5
4
3
2
1
Bit 0
Read:
PTB7
Write:
PTB6
PTB5
PTB4
PTB3
PTB2
PTB1
PTB0
Reset:
Unaffected by reset
Figure 12-5. Port B Data Register (PTB)
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.
MC68HC908QB8 Data Sheet, Rev. 3
106
Freescale Semiconductor