Freescale Semiconductor MC68HC08KH12 - Manual (Page 188)

Advance Information MC68HC(7)08KH12 — Rev. 1.1
188 Freescale Semiconductor
12.4 Port B
Port B is an 8-bit general-purpose bidirectional I/O port with software
configurable pullups.
12.4.1 Port B Data Register (PTB)
The port B data register contains a data latch for each of the eight port B
pins.
PTB[7:0] — Port B Data Bits
These read/write bits are software-programmable. Data direction of
each port B pin is under the control of the corresponding bit in data
direction register B. Reset has no effect on port B data.
The port B pullup enable bit, PBP, in the port option control register
(POC) enables pullups on port B pins if the respective pin is configured
as an input.
(See 12.9 Port Options .).
Table 12-2. Port A Pin Functions
DDRA
Bit
PTA Bit
I/O Pin
Mode
Accesses
to DDRA
Accesses to PTA
Read/Write Read Write
0 X
(1)
Input, Hi-Z
(2)
DDRA[7:0] Pin PTA[7:0]
(3)
1 X Output DDRA[7:0] PTA[7:0] PTA[7:0]
1. X = don’t care
2. Hi-Z = high impedance
3. Writing affects data register, but does not affect input.
Address: $0001
Bit 7 6 5 4 3 2 1 Bit 0
Read:
PTB7 PTB6 PTB5 PTB4 PTB3 PTB2 PTB1 PTB0
Write:
Reset: Unaffected by reset
Figure 12-4. Port B Data Register (PTB)