Datasheet

General Description
Pin Assignments
MC68HC908JB8•MC68HC08JB8•MC68HC08JT8 — Rev. 2.3 Technical Data
Freescale Semiconductor General Description 37
When the USB module is disabled, the PTE4 and PTE3 pins are
general-purpose bidirectional I/O port pins with 10mA sink capability.
Each pin is open-drain when configured as an output; and each pin
contains a software configurable 5kΩ pullup to V
DD
when configured as
an input. The PTE4 pin can also be enabled to trigger the IRQ interrupt.
When the USB module is enabled, the PTE4/D– and PTE3/D+ pins
become the USB module D– and D+ pins. The D– pin contains a
software configurable 1.5kΩ pullup to V
REG
. (See Section 11. Timer
Interface Module (TIM), Section 9. Universal Serial Bus Module
(USB) and Section 12. Input/Output Ports (I/O).)
Summary of the pin functions are provided in Table 1-1.
Table 1-1. Summary of Pin Functions
PIN NAME PIN DESCRIPTION IN/OUT VOLTAGE LEVEL
V
DD
Power supply. IN 4.0 to 5.5V
V
SS
Power supply ground. OUT 0V
V
REG
Regulated 3.3V output from MCU. OUT
V
REG
(3.3V)
RST
Reset input; active low.
With internal pullup to V
DD
and schmitt trigger input.
IN/OUT
V
DD
IRQ
External IRQ pin; with programmable internal pullup to V
DD
and schmitt trigger input.
IN
V
DD
Used for mode entry selection. IN
V
REG
to V
DD
+V
HI
OSC1 Crystal oscillator input. IN
V
REG
OSC2 Crystal oscillator output; inverting of OSC1 signal. OUT
V
REG
PTA0/KBA0
:
PTA7/KBA7
8-bit general-purpose I/O port. IN/OUT
V
REG
Pins as keyboard interrupts, KBA0–KBA7.IN
V
REG
Each pin has programmable internal pullup to V
REG
when
configured as input.
IN
V
REG
PTB0–PTB7
8-bit general-purpose I/O port. IN/OUT
V
REG
Each pin has programmable internal pullup to V
REG
when
configured as input.
IN
V
REG