S9S08AW16A FREESCALE [Freescale Semiconductor, Inc], S9S08AW16A Datasheet - Page 92

• Manufacturer Part Number: S9S08AW16A
• Description: HCS08 Microcontrollers
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

1
1
Chapter 6 Parallel Input/Output
6.7.3
Port B parallel I/O function is controlled by the registers in this section.
92
PTBDD[3:0]
Bits 7 through 4 are reserved bits that must always be written to 0.
Bits 7 through 4 are reserved bits that must always be written to 0.
PTBD[3:0]
Reset
Reset
Field
Field
3:0
3:0
W
W
R
R
Port B I/O Registers (PTBD and PTBDD)
Port B Data Register Bits — For port B pins that are inputs, reads return the logic level on the pin. For port B
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 B pins that are configured as outputs, the logic level is
driven out the corresponding MCU pin.
Reset forces PTBD 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 pullups disabled.
Data Direction for Port B Bits — These read/write bits control the direction of port B pins and what is read for
PTBD reads.
0 Input (output driver disabled) and reads return the pin value.
1 Output driver enabled for port B bit n and PTBD reads return the contents of PTBDn.
R
R
0
0
7
7
R
R
0
0
6
6
Figure 6-16. Data Direction for Port B (PTBDD)
Table 6-7. PTBDD Register Field Descriptions
Table 6-6. PTBD Register Field Descriptions
Figure 6-15. Port B Data Register (PTBD)
MC9S08AC16 Series Data Sheet, Rev. 8
R
R
0
0
5
5
R
R
0
0
4
4
Description
Description
PTBDD3
PTBD3
3
0
3
0
PTBDD2
PTBD2
1
0
0
2
2
1
PTBDD1
Freescale Semiconductor
PTBD1
0
0
1
1
PTBDD0
PTBD0
0
0
0
0