MC68HC08LT8 Datasheet, PDF (104/156 Pages) Freescale Semiconductor, Inc – Microcontrollers

Input/Output (I/O) Ports
9.6 Port E
Port E is an 8-bit special function port that shares all of its port pins with the liquid crystal display (LCD)
driver module.
9.6.1 Port E Data Register (PTE)
The port E data register contains a data latch for each of the eight port E pins.
Address:
Read:
Write:
Reset:
Alternative Function:
$0009
Bit 7
PTE7
FP10
6
PTE6
FP9
5
PTE5
FP8
4
3
PTE4
PTE3
Unaffected by reset
FP7
FP6
2
PTE2
FP5
1
PTE1
FP4
Bit 0
PTE0
FP3
Figure 9-15. Port E Data Register (PTE)
PTE[7:0] — 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 E data.
FP[10:3] — LCD Driver Frontplanes 10–3
FP[10:3] are pins used for the frontplane output of the LCD driver module. The enable bit, PEE, in the
CONFIG2 register and LCDE bit in the LCDCR register, determines whether the
PTE7/FP10–PTE0/FP3 pins are LCD frontplane driver pins or general-purpose I/O pins.
See Chapter 8 Liquid Crystal Display (LCD) Driver.
9.6.2 Data Direction Register E (DDRE)
Data direction register E determines whether each port E pin is an input or an output. Writing a logic 1 to
a DDRE bit enables the output buffer for the corresponding port E pin; a logic 0 disables the output buffer.
Address:
Read:
Write:
Reset:
$0008
Bit 7
6
5
4
3
2
1
DDRE7 DDRE6 DDRE5 DDRE4 DDRE3 DDRE2 DDRE1
0
0
0
0
0
0
0
Figure 9-16. Data Direction Register E (DDRE)
Bit 0
DDRE0
0
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. Figure 9-14 shows the
port E I/O logic.
MC68HC08LT8 Data Sheet, Rev. 1
104
Freescale Semiconductor