s908gr32ag3vfa Freescale Semiconductor, Inc, s908gr32ag3vfa Datasheet - Page 146

• Manufacturer Part Number: s908gr32ag3vfa
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Input/Output (I/O) Ports
RxD — SCI Receive Data Input
TxD — SCI Transmit Data Output
12.7.2 Data Direction Register E
Data direction register E (DDRE) 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.
DDRE5–DDRE0 — Data Direction Register E Bits
Figure 12-19
When bit DDREx is a 1, reading address $0008 reads the PTEx data latch. When bit DDREx is a 0,
reading address $0008 reads the voltage level on the pin. The data latch can always be written,
regardless of the state of its data direction bit.
146
The PTE1/RxD pin is the receive data input for the ESCI module.
When the enable SCI bit, ENSCI, is clear, the ESCI module is disabled, and the PTE1/RxD pin is
available for general-purpose I/O. See
Module.
The PTE0/TxD pin is the transmit data output for the ESCI module. When the enable SCI bit, ENSCI,
is clear, the ESCI module is disabled, and the PTE0/TxD pin is available for general-purpose I/O. See
Chapter 13 Enhanced Serial Communications Interface (ESCI)
These read/write bits control port E data direction. Reset clears DDRE5–DDRE0, configuring all port
E pins as inputs.
1 = Corresponding port E pin configured as output
0 = Corresponding port E pin configured as input
shows the port E I/O logic.
Address:
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.
Reset:
Read:
Write:
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
$000C
Bit 7
0
0
Figure 12-18. Data Direction Register E (DDRE)
= Unimplemented
6
0
0
DDRE5
Chapter 13 Enhanced Serial Communications Interface (ESCI)
5
0
Table 12-6
NOTE
DDRE4
4
0
summarizes the operation of the port E pins.
DDRE3
3
0
Module.
DDRE2
2
0
DDRE1
1
0
Freescale Semiconductor
DDRE0
Bit 0
0