MC908AP8CFBE Datasheet, PDF (269/324 Pages) Freescale Semiconductor, Inc – Microcontrollers

READ DDRC ($0006)
WRITE DDRC ($0006)
RESET
WRITE PTC ($0002)
DDRCx
PTCx
Port D
PTCx ^#
READ PTC ($0002)
# PTC0 has schmitt trigger input.
Figure 16-11. Port C I/O Circuit
When DDRCx is a logic 1, reading address $0002 reads the PTCx data latch. When DDRCx is a logic 0,
reading address $0002 reads the voltage level on the pin. The data latch can always be written,
regardless of the state of its data direction bit.
Table 16-4 summarizes the operation of the port C pins.
Table 16-4. Port C Pin Functions
DDRC
Bit
PTC Bit
I/O Pin Mode
Accesses to DDRC
Read/Write
0
X⁽¹⁾
Input, Hi-Z⁽²⁾
DDRC[7:0]
1
X
Output
DDRC[7:0]
1. X = don’t care.
2. Hi-Z = high impedance.
3. Writing affects data register, but does not affect input.
Accesses to PTC
Read
Write
Pin
PTC[7:0]⁽³⁾
PTC[7:0]
PTC[7:0]
16.5 Port D
Port D is an 8-bit special function port that shares all of its pins with the keyboard interrupt module.
16.5.1 Port D Data Register (PTD)
The port D data register contains a data latch for each of the eight port D pins.
Address:
Read:
Write:
Reset:
Alternative Function:
$0003
Bit 7
6
5
4
3
2
PTD7
PTD6
PTD5
PTD4
PTD3
PTD2
Unaffected by reset
KBI7
KBI6
KBI5
KBI4
KBI3
KBI2
Figure 16-12. Port D Data Register (PTD)
1
PTD1
KBI1
Bit 0
PTD0
KBI0
MC68HC908AP Family Data Sheet, Rev. 4
Freescale Semiconductor
267