User’s Manual
40
4.5 Other Hardware
4.5.1 Clock Doubler
The clock doubler on the RCM4510W is disabled by default.
4.5.2 Spectrum Spreader
The Rabbit 4000 features a spectrum spreader, which helps to mitigate EMI problems. The spec-
trum spreader is on by default, 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.
NOTE:
Refer to the
Rabbit 4000 Microprocessor User’s Manual
for more information on the
spectrum-spreading setting and the maximum clock speed.
1. Select the “Defines” tab from the Dynamic C
Options > Project Options
menu.
2. Normal spreading is the default, and usually no entry is needed. If you need to specify
normal spreading, add the line
ENABLE_SPREADER=1
For strong spreading, add the line
ENABLE_SPREADER=2
To disable the spectrum spreader, add the line
ENABLE_SPREADER=0
NOTE:
The strong spectrum-spreading setting is not recommended since it may limit
the maximum clock speed or the maximum baud rate. It is unlikely that the strong set-
ting will be used in a real application.
3. Click
OK
to save the macro. The spectrum spreader will be set according to the macro
value whenever a program is compiled using this project file.
