User’s Manual
25
2.7.3 Spectrum Spreader
Jackrabbit boards that carry the CE mark have a Rabbit 2000 microprocessor that features a
spectrum spreader, which helps to mitigate EMI problems. By default, the spectrum
spreader is on automatically for Jackrabbit BL1810 and BL1820 boards that carry the CE
mark when used with Dynamic C 7.32 or later versions, but the spectrum spreader may also
be turned off or set to a stronger setting. The means for doing so is through a simple change
to the following BIOS line in a way that is similar to the clock doubler described above.
#define ENABLE_SPREADER 1 // Set to 0 to disable spectrum spreader
// 1 to enable normal spreading, or
// 2 to enable strong spreading.
NOTE: The spectrum spreader is off by default for Jackrabbit BL1800 models, and needs
to be enabled for them to be CE-compliant. To allow the flash memory and RAM chips
to accomodate the occasional higher frequencies associated with the spectrum spreader
being turned on for the Jackrabbit BL1800 models only, you will need at least one wait
state for both the flash memory and the RAM. The strong spectrum-spreading setting is
not needed for any Jackrabbit board.
The number of wait states is specified in the following code from the
LIB\BOARDTYPES
library. (There are 0 wait states by default.)
#ifndef NUM_RAM_WAITST
#define NUM_RAM_WAITST 0
#endif
#ifndef NUM_FLASH_WAITST
#define NUM_FLASH_WAITST 0
#endif
There is no spectrum spreader functionality for Jackrabbit boards that do not carry the CE
mark or when using any Jackrabbit with a version of Dynamic C prior to 7.30.
Содержание BL1800
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