K60P100M100SF2RM Datasheet, PDF (1104/1809 Pages) Freescale Semiconductor, Inc – K60 Sub-Family Reference Manual

Functional Description
t_mark = (CMD1:CMD2 + 1) ÷ (f_CMTCLK ÷ 8)
t_space = CMD3:CMD4 ÷ (f_CMTCLK ÷ 8)
where CMD1:CMD2 and CMD3:CMD4 are the decimal values of the concatenated
registers.
CMTCLK 8
C A R R IE R O U T (fcg)
MODULATOR GATE
MARK
SPACE
MARK
IRO SIGNAL (TIME MODE)
IRO SIGNAL
(BASEBAND MODE)
Figure 42-17. Example: CMT Output in Time and Baseband Modes with OC[CMTPOL]=0
42.7.3.2 Baseband Mode
Baseband mode (MSC[MCGEN] and MSC[BASE] bits are set) is a derivative of time
mode, where the mark and space period is based on (CMTCLK ÷ 8) counts. The mark
and space calculations are the same as in time mode. In this mode, the modulator output
will be at a logic 1 for the duration of the mark period and at a logic 0 for the duration of
a space period. See Figure 42-17 for an example of the output for both baseband and time
modes. In the example, the carrier out frequency (f_cg) is generated with a high count of
0x01 and a low count of 0x02 that results in a divide of 3 of CMTCLK with a 33% duty
cycle. The modulator down counter was loaded with the value 0x0003 and the space
period register with 0x0002.
1104
K60 Sub-Family Reference Manual, Rev. 6, Nov 2011
Freescale Semiconductor, Inc.