Other Hardware; Clock Doubler; Spectrum Spreader - Z-World Wolf BL2600 User Manual

C-programmable single-board computer with ethernet

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3.8 Other Hardware

The BL2600 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 emis-

sions. The 44.2 MHz frequency specified for the BL2600 is generated using a 22.12 MHz

resonator.

The clock doubler may be disabled if 44.2 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 change

to the BIOS as described below.

1. Open the BIOS source code file,

2. Change the line

#define CLOCK_DOUBLED 1 // set to 1 to double clock if

to read as follows.

#define CLOCK_DOUBLED 0

3. Save the change using

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 change to the following BIOS

line in a way that is similar to the clock doubler described above.

#define ENABLE_SPREADER 1

#define SPREADER_SETTING 0 // 0 = normal spreading, 1 = strong spreading

NOTE: The strong spectrum-spreading setting is not recommended since it may limit the

maximum clock speed or the maximum baud rate.

RABBITBIOS.C

// Rabbit 2000: crystal <= 12.9024 MHz,

// Rabbit 3000: crystal <= 26.7264 MHz,

// or to 0 to always disable clock doubler

File > Save

// Set to 0 to disable spectrum spreader.

in the

directory.

BIOS

Wolf (BL2600)

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