MC68HC908JB8 Datasheet, PDF (206/286 Pages) Motorola, Inc – MICROCONTROLLERS

Input/Output Ports (I/O)
READ DDRB ($0005)
WRITE DDRB ($0005)
RESET
WRITE PTB ($0001)
READ PTB ($0001)
DDRBx
PTBx
PTBx
Figure 12-7. Port B I/O Circuit
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. Table 12-3 summarizes
the operation of the port B pins.
Table 12-3. Port B Pin Functions
DDRB
Bit
0
1
PTB Bit
X⁽¹⁾
X
I/O Pin Mode
Accesses
to DDRB
Read/Write
Input, Hi-Z^{(2) DDRB[7:0]}
Output
DDRB[7:0]
Accesses to PTB
Read
Pin
PTB[7:0]
Write
PTB[7:0]⁽³⁾
PTB[7:0]
NOTES:
1. X = don’t care.
2. Hi-Z = high impedance.
3. Writing affects data register, but does not affect input.
Technical Data
206
MC68HC908JB8•MC68HC08JB8•MC68HC08JT8 — Rev. 2.3
Input/Output Ports (I/O)
Freescale Semiconductor