Clock Input Select Header (J17) - Motorola M68705EVM User Manual

2.3.6 Clock Input Select Header (J17)
Jumper header J17 is used to select either internal or external clock source to be used by the
EVM. The internal clock source is a 4 MHz crystal. The EVM is factory-configured and
shipped with the clock input selected to internal 4 MHz clock operation. This is accomplished
by the installation of a fabricated jumper on pins 2 and 3 as shown below. To select an
external clock source, remove jumper from pins 2 and 3, and reinstall jumper on pins 1 and 2.
J17
•
EXTERNAL (EXT)
2
I
INTERNAL (4 MHz)
3
When the external clock source is selected, connector J18 (2-pin header) is used to facilitate
interconnection of the external clock source.
EVALUATION MODULE USER'S MANUAL
2-8
J18
• INPUT
2 • GND
EXTCLK
MOTOROLA
M68705EVM