MC68HC908GT16 Datasheet, PDF (245/412 Pages) Motorola, Inc – Microcontrollers

16.7 Port E
Input/Output (I/O) Ports
Port E
Port E is a 5-bit special-function port that shares two of its pins with the
serial communications interface (SCI) module and two of its pins with the
internal clock generator (ICG).
16.7.1 Port E Data Register
The port E data register contains a data latch for each of the five port E
pins.
Address: $0008
Bit 7
6
Read: 0
0
Write:
Reset:
Alternate
Function:
5
4
3
2
1
0
PTE4 PTE3 PTE2 PTE1
Unaffected by reset
OSC1 OSC2
RxD
= Unimplemented
Figure 16-17. Port E Data Register (PTE)
Bit 0
PTE0
TxD
PTE4-PTE0 — Port E Data Bits
These read/write bits are software-programmable. Data direction of
each port E pin is under the control of the corresponding bit in data
direction register E. Reset has no effect on port Edata.
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 or the states of the pins. See Table 16-6.
OSC2 and OSC1 — OSC2 and OSC1 Bits
Under software control, PTE4 and PTE3 can be configured as
external clock inputs and outputs. PTE3 will become an output clock,
OSC2, if selected in the configuration registers and enabled in the
MC68HC908GT16 • MC68HC908GT8 — Rev. 2
MOTOROLA
Input/Output (I/O) Ports
Technical Data
245