Clock Select Header (J2) - Motorola M68HC11EVB User Manual

HARDWARE PREPARATION AND INSTALLATION
2.3.2

Clock Select Header (J2)

Jumper header J2 is used to select either internal or external clock source to be used by the EVB.
The internal EVB clock source is an 8 MHz crystal for a bus rate of 2 MHz. The EVB is factory-
configured and shipped with the clock input selected for internal clock source. This is
accomplished by the installation of a fabricated jumper on pins 2 and 3 as shown below.
J2
1 2 3
External Internal
If an external TTL clock source from the target system (via MCU I/O port connector P1, pin 7)
is required, the jumper is repositioned between pins 1 and 2.
M68HC11EVB/D 2-3 3