Datasheet

Input/Output (I/O) Ports (PORTS)
MC68HC908KX8 • MC68HC908KX2 • MC68HC08KX8 Data Sheet, Rev. 2.1
110 Freescale Semiconductor
When bit DDRBx is a 1, reading address $0001 reads the PTBx data latch. When bit DDRBx is a 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 11-2 summarizes the operation of the port B pins.
Table 11-2. Port B Pin Functions
DDRB
Bit
PTB
Bit
I/O Pin
Mode
Accesses to DDRB Accesses to PTB
Read/Write Read Write
0 X Input, Hi-Z DDRB7–DDRB0 Pin
PTB7–PTB0
(1)
1. Writing affects data register, but does not affect input.
1 X Output DDRB7–DDRB0 PTB7–PTB0 PTB7–PTB0
X = Don’t care
Hi-Z = High impedance