
Input/Output (I/O) Ports
MC68HC08AZ32A Data Sheet, Rev. 2
164
Freescale Semiconductor
TACH[1:0] — Timer A Channel I/O Bits
The PTE3/TACH1–PTE2/TACH0 pins are the TIMA input capture/output compare pins. The
edge/level select bits, ELSxB:ELSxA, determine whether the PTE3/TACH1–PTE2/TACH0 pins are
NOTE
Data direction register E (DDRE) does not affect the data direction of port
E pins that are being used by the TIMA. However, the DDRE bits always
determine whether reading port E returns the states of the latches or the
RxD — SCI Receive Data Input
The PTE1/RxD pin is the receive data input for the SCI module. When the enable SCI bit, ENSCI, is
clear, the SCI module is disabled, and the PTE1/RxD pin is available for general-purpose I/O. See
TxD — SCI Transmit Data Output
The PTE0/TxD pin is the transmit data output for the SCI module. When the enable SCI bit, ENSCI, is
clear, the SCI module is disabled, and the PTE0/TxD pin is available for general-purpose I/O. See
NOTE
Data direction register E (DDRE) does not affect the data direction of port
E pins that are being used by the SCI module. However, the DDRE bits
always determine whether reading port E returns the states of the latches
13.6.2 Data Direction Register E (DDRE)
Data direction register E determines whether each port E pin is an input or an output. Writing a 1 to a
DDRE bit enables the output buffer for the corresponding port E pin; a 0 disables the output buffer.
DDRE[7:0] — Data Direction Register E Bits
These read/write bits control port E data direction. Reset clears DDRE[7:0], configuring all port E pins
as inputs.
1 = Corresponding port E pin configured as output
0 = Corresponding port E pin configured as input
NOTE
Avoid glitches on port E pins by writing to the port E data register before
changing data direction register E bits from 0 to 1.
Address: $000C
Bit 7
654321
Bit 0
Read:
DDRE7
DDRE6
DDRE5
DDRE4
DDRE3
DDRE2
DDRE1
DDRE0
Write:
Reset:
00000000
Figure 13-15. Data Direction Register E (DDRE)