101-1006 Rabbit Semiconductor, 101-1006 Datasheet - Page 50

• Manufacturer Part Number: 101-1006
• Description: MODULE POWERCORE FLEX 3800
• Manufacturer: Rabbit Semiconductor

Specifications of 101-1006

• Module/board Type: MPU Core Module
• For Use With/related Products: RCM3800
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

4.5 Other Hardware
4.5.1 Clock Doubler
The PowerCore takes advantage of the Rabbit 3000 microprocessor’s internal clock doubler.
A built-in clock doubler allows half-frequency crystals to be used to reduce radiated
emissions. The 51.6 MHz frequency specified for the PowerCore is generated using a
25.8 MHz crystal.
The clock doubler may be disabled if 51.6 MHz clock speeds are not required. This will
reduce power consumption and further reduce radiated emissions. The clock doubler is
disabled with a simple configuration macro as shown below.
The clock doubler is automatically off for 25.8 MHz modules. Fast SRAM is needed to
run programs when clock speeds are above 30 MHz.
4.5.2 Spectrum Spreader
The Rabbit 3000 features a spectrum spreader, which helps to mitigate EMI problems. By
default, the spectrum spreader is on automatically, but it may also be turned off or set to a
stronger setting. The means for doing so is through a simple configuration macro as shown
below.
42
1. Select the “Defines” tab from the Dynamic C
2. Add the line
3. Click
1.
2. Normal spreading is the default, and usually no entry is needed. If you need to specify nor-
3.
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
always enable the clock doubler.
in the project file where you defined the macro.
Select the “Defines” tab from the Dynamic C Options > Project Options menu.
mal spreading, add the line
For strong spreading, add the line
To disable the spectrum spreader, add the line
Click OK to save the macro. The spectrum spreader will now remain off whenever you are
in the project file where you defined the macro.
ENABLE_SPREADER=1
ENABLE_SPREADER=2
ENABLE_SPREADER=0
TIP: If you wish to add more than one macro definition to the Global Macro Definitions
NOTE: The strong spectrum-spreading setting is not recommended since it may limit
OK
box, the macros should be separated by semi-colons.
the maximum clock speed or the maximum baud rate. It is unlikely that the strong
setting will be used in a real application.
to save the macro. The clock doubler will now remain off whenever you are
CLOCK_DOUBLED=0
to always disable the clock doubler.
Options > Project Options
CLOCK_DOUBLED=1
PowerCore FLEX
menu.
to