Carrier Modulator Transmitter (CMT)

The mark and space time equations for FSK mode are:

tmark = MBUFF-------------------------------+ 1 sec s

 

fcg

tspace =

SBUFF--------------------secs

 

fcg

Where fcg is the frequency output from the carrier generator, setting the

DIV2 bit in the MCSR will double mark and space times.

9.5.3 Extended Space Operation

In either time or FSK mode, the space period can be made longer than the maximum possible value of SBUFF. Setting the EXSPC bit in the MCSR will force the modulator to treat the next modulation period (beginning with the next load of MBUFF/SBUFF) as a space period equal in length to the mark and space counts combined. Subsequent modulation periods will consist entirely of these extended space periods with no mark periods. Clearing EXSPC will return the modulator to standard operation at the beginning of the next modulation period. To calculate the length of an extended space in time mode, use the equation:

((SBUFF1)+(MBUFF2+1+SBUFF2) +... (MBUFFn+1+SBUFFn)) x 8

texspace =secs fosc

Where:

the subscripts 1, 2, ... n refer to the modulation periods that elapsed while the EXSPC bit was set.

Similarly, to calculate the length of an extended space in FSK mode, use the equation:

texspace =

((SBUFF1)+(MBUFF2+1+SBUFF2)+... (MBUFFn+1+SBUFFn))

secs

fcg

 

 

 

 

General Release Specification

 

MC68HC05RC16 — Rev. 3.0

 

 

 

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Carrier Modulator Transmitter (CMT)

MOTOROLA