MC908AS60ACFU Datasheet, PDF (265/414 Pages) Freescale Semiconductor, Inc – M68HC08 Microcontrollers

Port H
22.9 Port H
Port H is a 2-bit special function port that shares all of its pins with the keyboard interrupt module (KBD).
Note that Port H is only available on 64-pin package options.
22.9.1 Port H Data Register
The port H data register contains a data latch for each of the two port H pins.
Address:
Read:
Write:
Reset:
Alternative
Function:
$000B
Bit 7
0
R
R
6
5
4
3
2
0
0
0
0
0
R
R
R
R
R
Unaffected by Reset
= Reserved
Figure 22-23. Port H Data Register (PTH)
1
PTH1
KBD4
Bit 0
PTH0
KBD3
PTH[1:0] — Port H Data Bits
These read/write bits are software programmable. Data direction of each port H pin is under the control
of the corresponding bit in data direction register H. Reset has no effect on PTH[1:0].
KBD[4:3] — Keyboard Wake-up pins
The keyboard interrupt enable bits, KBIE[4:3], in the keyboard interrupt control register, enable the port
H pins as external interrupt pins (See Chapter 24 Keyboard Module (KBI)).
22.9.2 Data Direction Register H
Data direction register H determines whether each port H pin is an input or an output. Writing a logic 1 to
a DDRH bit enables the output buffer for the corresponding port H pin; a logic 0 disables the output buffer.
Address:
Read:
Write:
Reset:
$000F
Bit 7
6
5
4
3
2
1
0
0
0
0
0
0
DDRH1
R
R
R
R
R
R
0
0
0
0
0
0
0
R
= Reserved
Figure 22-24. Data Direction Register H (DDRH)
Bit 0
DDRH0
0
DDRH[1:0] — Data Direction Register H Bits
These read/write bits control port H data direction. Reset clears DDRG[1:0], configuring all port H pins
as inputs.
1 = Corresponding port H pin configured as output
0 = Corresponding port H pin configured as input
NOTE
Avoid glitches on port H pins by writing to the port H data register before
changing data direction register H bits from 0 to 1.
MC68HC908AZ60A • MC68HC908AS60A • MC68HC908AS60E Data Sheet, Rev. 6
Freescale Semiconductor
265