Clock Source Select Header (P6); Clock Divider Header (P9) - Motorola M68EM05A24 User Manual

2.1.3

Clock Source Select Header (P6)

2.1.4

Clock Divider Header (P9)

FABRICATED
HC05A24EM USER'S MANUAL
Jumper header P6 determines the source of the clock signal. The dia-
gram below shows the factory configuration: the fabricated jumper
between pins 2 and 3 selects the A24EM canned oscillator clock source.
FABRICATED
JUMPER
Alternatively, you may use a clock source originating from the control
board. To do so, reposition the P6 jumper between pins 1 and 2, then use
the MMDS05 OSC command to select a frequency.
Jumper header P9 determines which internal clock divider of the MCU
to use on power up or reset. The diagram below shows the factory con-
figuration: the fabricated jumper between pins 1 and 2 selects the divide
by two MCU clock divider. This is the correct configuration for a 4 MHz
clock source. If a 16 MHz clock source is used. The user must remove
the fabricated jumper between pins 1 and 2 to select the divide by eight
MCU clock divider.
INTERNAL
CLOCK DIVIDER
P9
JUMPER
P6
1
MMDS05
2
XTAL
3
1
OPEN = OSC/8
CLOSE = OSC/2
2
2
MOTOROLA
2-3