HC05RC17GRSSLASHD datasheet(80/128 Pages) NXP

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Carrier Modulator Transmitter (CMT)

General Release Specification

MC68HC05RC17 — Rev. 2.0

Carrier Modulator Transmitter (CMT)

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:

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:

Where fcg is the frequency output from the carrier generator. For an

example of extended space operation, see Figure 9-6.

NOTE:

The EXSPC feature can be used to emulate a zero mark event.

Figure 9-6. Extended Space Operation

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

fosc

texspace =

secs

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

fcg

texspace =

secs

SET EXSPC

CLEAR EXSPC

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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