PIC12F1840 MICROCHIP [Microchip Technology], PIC12F1840 Datasheet - Page 179

• Manufacturer Part Number: PIC12F1840
• Description: 8-Pin Flash Microcontrollers with nanoWatt XLP Technology
• Manufacturer: MICROCHIP [Microchip Technology]

23.0
The Data Signal Modulator (DSM) is a peripheral which
allows the user to mix a data stream, also known as a
modulator signal, with a carrier signal to produce a
modulated output.
Both the carrier and the modulator signals are supplied
to the DSM module either internally, from the output of
a peripheral, or externally through an input pin.
The modulated output signal is generated by perform-
ing a logical “AND” operation of both the carrier and
modulator signals and then provided to the MDOUT pin.
The carrier signal is comprised of two distinct and sep-
arate signals. A carrier high (CARH) signal and a car-
rier low (CARL) signal. During the time in which the
modulator (MOD) signal is in a logic high state, the
DSM mixes the carrier high signal with the modulator
signal. When the modulator signal is in a logic low
state, the DSM mixes the carrier low signal with the
modulator signal.
FIGURE 23-1:
 2011 Microchip Technology Inc.
Comparator C1
MSSP1 SDO1
MDCL<3:0>
MDCH<3:0>
MDMS<3:0>
No Channel
No Channel
No Channel
DATA SIGNAL MODULATOR
Reserved
Reserved
Reserved
Reserved
Reserved
EUSART
MDCIN1
MDCIN2
MDCIN1
MDCIN2
Reserved
Reserved
Reserved
MDMIN
Selected
Selected
Selected
MDBIT
CLKR
CCP1
CCP1
CLKR
CCP1
V
V
SS
SS
0000
0001
0010
0000
0001
0010
0000
0001
0010
0011
0100
0101
*
*
*
1111
0011
0100
0101
0110
0111
1000
1001
1010
0011
*
*
1111
0011
0100
0101
1111
*
*
*
SIMPLIFIED BLOCK DIAGRAM OF THE DATA SIGNAL MODULATOR
MOD
CARL
CARH
MDCHPOL
MDCLPOL
MDEN
EN
Preliminary
D
D
SYNC
SYNC
Data Signal
Modulator
Q
Q
MDCLSYNC
Using this method, the DSM can generate the following
types of Key Modulation schemes:
• Frequency-Shift Keying (FSK)
• Phase-Shift Keying (PSK)
• On-Off Keying (OOK)
Additionally, the following features are provided within
the DSM module:
• Carrier Synchronization
• Carrier Source Polarity Select
• Carrier Source Pin Disable
• Programmable Modulator Data
• Modulator Source Pin Disable
• Modulated Output Polarity Select
• Slew Rate Control
Figure 23-1
Data Signal Modulator peripheral.
MDCHSYNC
1
0
1
0
shows a Simplified Block Diagram of the
PIC12F/LF1840
MDOPOL
MDOE
DS41441A-page 179
MDOUT