mc9s08sg4 Freescale Semiconductor, Inc, mc9s08sg4 Datasheet - Page 78

• Manufacturer Part Number: mc9s08sg4
• Description: 8-bit Microcontroller Family
• Manufacturer: Freescale Semiconductor, Inc

Chapter 6 Parallel Input/Output Control
6.6.1
Port A is controlled by the registers listed below.
6.6.1.1
6.6.1.2
78
PTADD[3:0]
PTAD[3:0]
Reserved
Reserved
Reset:
Reset:
Field
Field
5:4
3:0
5:4
3:0
W
W
R
R
Port A Registers
Reserved Bits — These bits are unused on this MCU, writes have no affect and could read as 1s or 0s.
Port A Data Register Bits — For port A pins that are inputs, reads return the logic level on the pin. For port A
pins that are configured as outputs, reads return the last value written to this register.
Writes are latched into all bits of this register. For port A pins that are configured as outputs, the logic level is
driven out the corresponding MCU pin.
Reset forces PTAD to all 0s, but these 0s are not driven out the corresponding pins because reset also configures
all port pins as high-impedance inputs with pull-ups/pull-downs disabled.
Reserved Bits — These bits are unused on this MCU, writes have no affect and could read as 1s or 0s.
Data Direction for Port A Bits — These read/write bits control the direction of port A pins and what is read for
PTAD reads.
0 Input (output driver disabled) and reads return the pin value.
1 Output driver enabled for port A bit n and PTAD reads return the contents of PTADn.
Port A Data Register (PTAD)
0
0
Port A Data Direction Register (PTADD)
0
0
7
7
0
0
0
0
6
6
Figure 6-4. Port A Data Direction Register (PTADD)
Table 6-3. PTADD Register Field Descriptions
Table 6-2. PTAD Register Field Descriptions
Figure 6-3. Port A Data Register (PTAD)
MC9S08SG8 MCU Series Data Sheet, Rev. 3
R
R
0
0
5
5
R
R
0
0
4
4
Description
Description
PTADD3
PTAD3
3
0
3
0
PTADD2
PTAD2
0
0
2
2
PTADD1
Freescale Semiconductor
PTAD1
0
0
1
1
PTADD0
PTAD0
0
0
0
0