Datasheet

Port H
MC68HC908AZ60A • MC68HC908AS60A • MC68HC908AS60E Data Sheet, Rev. 6
Freescale Semiconductor 265
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.
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.
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.
Address: $000B
Bit 7654321Bit 0
Read:000000
PTH1 PTH0
Write:RRRRRR
Reset: Unaffected by Reset
Alternative
Function:
KBD4 KBD3
R= Reserved
Figure 22-23. Port H Data Register (PTH)
Address: $000F
Bit 7654321Bit 0
Read:000000
DDRH1 DDRH0
Write:RRRRRR
Reset:00000000
R= Reserved
Figure 22-24. Data Direction Register H (DDRH)