MC9S08SH8CSC 查看數據表（PDF） - Freescale Semiconductor
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MC9S08SH8CSC Datasheet PDF : 341 Pages
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6.6.2 Port B Registers
Port B is controlled by the registers listed below.
6.6.2.1 Port B Data Register (PTBD)
Chapter 6 Parallel Input/Output Control
R
W
Reset:
7
PTBD7
0
6
PTBD6
5
PTBD5
4
PTBD4
3
PTBD3
2
PTBD2
0
0
0
0
0
Figure 6-11. Port B Data Register (PTBD)
Table 6-10. PTBD Register Field Descriptions
1
PTBD1
0
0
PTBD0
0
Field
Description
7:0
PTBD[7:0]
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 pull-ups/pull-downs disabled.
6.6.2.2 Port B Data Direction Register (PTBDD)
R
W
Reset:
7
PTBDD7
0
6
PTBDD6
5
PTBDD5
4
PTBDD4
3
PTBDD3
2
PTBDD2
0
0
0
0
0
Figure 6-12. Port B Data Direction Register (PTBDD)
Table 6-11. PTBDD Register Field Descriptions
1
PTBDD1
0
0
PTBDD0
0
Field
Description
7:0
Data Direction for Port B Bits — These read/write bits control the direction of port B pins and what is read for
PTBDD[7:0] 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.
MC9S08SH8 MCU Series Data Sheet, Rev. 3
Freescale Semiconductor
85
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