20-101-0492 Rabbit Semiconductor, 20-101-0492 Datasheet - Page 28

• Manufacturer Part Number: 20-101-0492
• Description: MODULE OP6800 FULL-FEATURED
• Manufacturer: Rabbit Semiconductor

Specifications of 20-101-0492

• Module/board Type: Single Board Computer Module
• For Use With/related Products: OP6800
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 20-101-492; 20-101-492

3.5 Other Hardware
3.5.1 Clock Doubler
The OP6800 takes advantage of the Rabbit 2000 microprocessor’s internal clock doubler.
A built-in clock doubler allows half-frequency crystals to be used to reduce radiated emis-
sions. The 22.1 MHz frequency is generated using an 11.0592 MHz crystal. The clock
doubler is disabled automatically in the BIOS for crystals with a frequency above
12.9 MHz.
The clock doubler may be disabled if 22.1 MHz clock speeds are not required. Disabling
the Rabbit 2000 microprocessor’s internal clock doubler will reduce power consumption
and further reduce radiated emissions. The clock doubler is disabled with a simple global
macro as shown below.
24
1.
2. Add the line
3. Click
Select the “Defines” tab from the Dynamic C Options > Project Options
The clock doubler is enabled by default, and usually no entry is needed. If you need to specify
that the clock doubler is always enabled, add the line CLOCK_DOUBLED=1
the clock doubler. The clock speed will be doubled as long as the crystal frequency is
less than or equal to 26.7264 MHz.
project file where you defined the macro.
OK to save the macro. The clock doubler will now remain off whenever you are in the
CLOCK_DOUBLED=0 to always disable the clock doubler.
to always enable
MiniCom (OP6800)
menu.