user manual

Carrier Modulator Transmitter (CMT)
Modulator
MC68HC05RC16 — Rev. 3.0 General Release Specification
MOTOROLA Carrier Modulator Transmitter (CMT) 75
The modulator can operate in two modes, time or FSK. In time mode the
modulator counts clocks derived from the system oscillator and
modulates a single-carrier frequency or no carrier (baseband). In FSK
mode, the modulator counts carrier periods and instructs the carrier
generator to alternate between two carrier frequencies whenever a
modulation period (mark + space counts) expires.
Figure 9-7. Modulator Block Diagram
=?
0
COUNTER
f
OSC
EOC FLAG
MBUFF
SBUFF
SREG *
13-BIT DOWN COUNTER *
* DENOTES HIDDEN REGISTER
12 BITS
12 BITS
MS BIT
12
12
CONTROL/STATUS REGISTER
MODULATOR
EOC INTERRUPT ENABLE
BASE
MODE
 8
CLOCK CONTROL
CARRIER OUT
LOAD MBUFF/SBUFF
SYSTEM CONTROL
EOC FLAG SET
MODULATOR GATE
OUT
PRIMARY/SECONDARY SELECT
.
.
MODULATOR
MODULATOR/
CARRIER GENERATOR.
ENABLE
EXTENDED SPACE
DIV2