101-0517 Rabbit Semiconductor, 101-0517 Datasheet - Page 33

• Manufacturer Part Number: 101-0517
• Description: MODULE RABBITCORE RCM3100
• Manufacturer: Rabbit Semiconductor

Specifications of 101-0517

• Rohs Status: RoHS non-compliant
• Module/board Type: MPU Core Module
• For Use With/related Products: RCM3100
• Other names: 316-1021

4.4 Other Hardware
4.4.1 Clock Doubler
The RCM3100 takes advantage of the Rabbit 3000 microprocessor’s internal clock dou-
bler. A built-in clock doubler allows half-frequency crystals to be used to reduce radiated
emissions. The 29.4 MHz frequency specified for the RCM3100 is generated using a
14.7456 MHz crystal. The clock doubler will not work for crystals with a frequency
above 26.7264 MHz.
The clock doubler may be disabled if 29.4 MHz clock speeds are not required. Disabling
the Rabbit 3000 microprocessor’s internal clock doubler will reduce power consumption
and further reduce radiated emissions. The clock doubler is disabled with a simple config-
uration macro as shown below.
4.4.2 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.
User’s Manual
1. Select the “Defines” tab from the Dynamic C
2. Add the line
3. Click
1. Select the “Defines” tab from the Dynamic C
2. Normal spreading is the default, and usually no entry is needed. If you need to specify
3. Click
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.
normal spreading, add the line
For strong spreading, add the line
To disable the spectrum spreader, add the line
are in the project file where you defined the macro.
ENABLE_SPREADER=1
ENABLE_SPREADER=2
ENABLE_SPREADER=0
NOTE: Refer to the Rabbit 3000 Microprocessor User’s Manual for more information
NOTE: The strong spectrum-spreading setting is unnecessary for the BL2000.
OK
OK
on the spectrum-spreading setting and the maximum clock speed.
to save the macro. The spectrum spreader will now remain off whenever you
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
Options > Project Options
CLOCK_DOUBLED=1
menu.
menu.
to
27