Pin Functions
1.5 Pin Functions
Description of the pin functions are provided in Table 1-2.
Table 1-2. Pin Functions
VOLTAGE
LEVEL
PIN NAME
PIN DESCRIPTION
IN/OUT
4.5 to 5.5
or
2.7 to 3.3
VDD
In
Power supply.
VSS
VDDA
VSSA
VREFH
VREFL
Out
In
0V
VDD
VSS
Power supply ground.
Power supply for analog circuits.
Power supply ground for analog circuits.
ADC input reference high.
Out
In
VDDA
VSSA
Out
ADC input reference low.
Internal (2.5V) regulator output.
Require external capacitors for decoupling.
2.5V(1)
VDD
VREG
RST
Out
In
Reset input, active low; with internal pullup and schmitt
trigger input.
External IRQ1 pin; with internal pullup and schmitt trigger
input.
VDD
In
IRQ1
VDD to VTST
VREG
In
In
Used for mode entry selection.
Crystal or RC oscillator input.
OSC1
Crystal OSC option: crystal oscillator output; inverted
OSC1.
VREG
Out
OSC2
VREG
VREG
Out
Out
RC OSC option: bus clock output.
Internal OSC option: bus clock output.
CGM external filter capacitor connection.
8-bit general purpose I/O port.
CGMXFC
In/Out
In/Out
In
Analog
VDD
PTA0/ADC0
VREFH
VDD
:
Pins as ADC inputs, ADC0–ADC7.
Each pin has high current sink for LED.
PTA7/ADC7
Out
MC68HC908AP Family Data Sheet, Rev. 4
Freescale Semiconductor
25
FREESCALE [ Freescale ]
