MC68HC08AZ32A Datasheet, PDF (160/312 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Input/Output (I/O) Ports
DDRC[5:0] — Data Direction Register C Bits
These read/write bits control port C data direction. Reset clears DDRC[7:0], configuring all port C pins
as inputs.
1 = Corresponding port C pin configured as output
0 = Corresponding port C pin configured as input
NOTE
Avoid glitches on port C pins by writing to the port C data register before
changing data direction register C bits from 0 to 1.
Figure 13-10 shows the port C I/O logic.
READ DDRC ($0006)
WRITE DDRC ($0006)
RESET
WRITE PTC ($0002)
DDRCx
PTCx
PTCx
READ PTC ($0002)
Figure 13-10. Port C I/O Circuit
When bit DDRCx is a 1, reading address $0002 reads the PTCx data latch. When bit DDRCx is a 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 13-3 summarizes the operation of the port C pins.
Table 13-3. Port C Pin Functions
DDRC
Bit
0
1
0
1
PTC
Bit
2
2
X⁽¹⁾
X
I/O Pin
Mode
Input, Hi-Z
Output
Input, Hi-Z⁽²⁾
Output
Accesses to DDRC
Read/Write
DDRC[7]
DDRC[7]
DDRC[5:0]
DDRC[5:0]
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
PTC2
0
—
Pin
PTC[5:0]⁽³⁾
PTC[5:0]
PTC[5:0]
MC68HC08AZ32A Data Sheet, Rev. 2
160
Freescale Semiconductor