
Clock and Phase Locked Loop Signals
56F805 Technical Data, Rev. 15
Freescale Semiconductor
11
2.3 Clock and Phase Locked Loop Signals
2.4 Address, Data, and Bus Control Signals
Table 2-5 PLL and Clock
No. of
Pins
Signal
Name
Signal
Type
State During
Reset
Signal Description
1
EXTAL
Input
Input
External Crystal Oscillator Input
—This input should be
connected to an 8MHz external crystal or ceramic resonator. For
more information, please refer to
Section 3.5
.
1
XTAL
Input/O
utput
Chip-driven
Crystal Oscillator Output
—This output should be connected to
an 8MHz external crystal or ceramic resonator. For more
information, please refer to
Section 3.5
.
This pin can also be connected to an external clock source. For
more information, please refer to
Section 3.5.3
.
1
CLKO
Output
Chip-driven
Clock Output
—This pin outputs a buffered clock signal. By
programming the CLKOSEL[4:0] bits in the CLKO Select
Register (CLKOSR), the user can select between outputting a
version of the signal applied to XTAL and a version of the
device’s master clock at the output of the PLL. The clock
frequency on this pin can also be disabled by programming the
CLKOSEL[4:0] bits in CLKOSR.
Table 2-6 Address Bus Signals
No. of
Pins
Signal
Name
Signal
Type
State During
Reset
Signal Description
6
A0–A5
Output
Tri-stated
Address Bus
—A0–A5 specify the address for external
Program or Data memory accesses.
2
A6–A7
GPIOE2
–
GPIOE3
Output
Input/O
utput
Tri-stated
Input
Address Bus
—A6–A7 specify the address for external
Program or Data memory accesses.
Port E GPIO
—These two General Purpose I/O (GPIO) pins
can be individually programmed as input or output pins.
After reset, the default state is Address Bus.
8
A8–A15
GPIOA0
–
GPIOA7
Output
Input/O
utput
Tri-stated
Input
Address Bus
—A8–A15 specify the address for external
Program or Data memory accesses.
Port A GPIO
—These eight General Purpose I/O (GPIO) pins
can be individually be programmed as input or output pins.
After reset, the default state is Address Bus.