mc68hc908jw32 Freescale Semiconductor, Inc, mc68hc908jw32 Datasheet - Page 171

• Manufacturer Part Number: mc68hc908jw32
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

DDRB[7:0] — Data Direction Register B Bits
Figure 13-7
When bit DDRBx is a logic 1, reading address $0001 reads the PTBx data latch. When bit DDRBx is a
logic 0, reading address $0001 reads the voltage level on the pin. The data latch can always be written,
regardless of the state of its data direction bit.
Freescale Semiconductor
These read/write bits control port B data direction. Reset clears DDRB[7:0], configuring all port B pins
as inputs.
1 = Corresponding port B pin configured as output
0 = Corresponding port B pin configured as input
shows the port B I/O circuit logic.
1. X = don’t care
2. Hi-Z = high impedance
3. Writing affects data register, but does not affect input.
Avoid glitches on port B pins by writing to the port B data register before
changing data direction register B bits from 0 to 1.
DDRB
Bit
0
1
READ DDRD ($0007)
WRITE DDRD ($0007)
WRITE PTD ($0003)
READ PTD ($0003)
PTB Bit
X
X
(1)
Table 13-3. Port B Pin Functions
RESET
MC68HC908JW32 Data Sheet, Rev. 5
Figure 13-7. Port B I/O Circuit
I/O Pin Mode
Input, Hi-Z
Output
Table 13-3
(2)
NOTE
DDRBx
PTBx
Read/Write
DDRB5,1,0
DDRB5,1,0
Accesses
to DDRB
summarizes the operation of the port B pins.
PTB5,1,0
Read
Pin
Accesses to PTB
PTB5,1,0
PTB5,1,0
Write
PTBx
(3)
Port B
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