DATA BULLETIN
MX828
Features
•
•
•
•
•
•
•
•
Fast CTCSS Detection
Full Duplex CTCSS and SelCall
Full 23/24 Bit DCS Codec
SelCall Codec
Non Predictive Tone Detection
Low Power 3.3V/5.0V Operation
Variable Gain Audio Filter
Programmable:
Tone Decoder
Tone Encoder
Modulator Drivers
Comparator for RSSI
•
Pin compatible with reduced function MX818
•
Full control via 4-Wire Serial Interface
CTCSS/DCS/SelCall
Processor
PRELIMINARY INFORMATION
Applications
•
Radio Systems Requiring Sub-Audible
Signaling
Trunking Control
Selective Calling
Group Calling
•
Increased Efficiency
Scanning Systems
Trunking Systems
CTCSS
RADIO
Tx MOD1
FAST CTCSS
SELCALL
DCS
CARRIER DETECT
MODULATOR
RF
DISCRIMINATOR
Tx MOD2
RSSI
ANALOG Rx
TIMER
LEVEL CONTROL
AUDIO
MSK
DTMF
LEVEL & VOLUME
CONTROLS
(OPTIONAL)
AUDIO
SIGNALS
AUDIO FILTER
MX828
KEYBOARD
HOST
µ
C
SERIAL C-BUS:
DATA & CONTROL
DISPLAY
MX829
The MX828 is a low power SelCall, CTCSS, and DCS signal processor designed for use in the latest generation of LMR
(Land Mobile Radio) equipment where sub-audible signaling is required for functions such as Trunking Control, Selective
Calling, and Group Calling applications. The MX828 is full duplex and offers many advanced features to assist in the
design of new Sub-Audible and in-band based systems. These include: a programmable tone decoder which may be set
to respond to between 1 and 15 CTCSS or SelCall tones with minimum software intervention, a Fast/Predictive CTCSS
detector that can respond to a single programmed tone in less than 60ms or provide an output if CTCSS tone is present at
the detector input, two high resolution tone encoders that accurately generate CTCSS or SelCall tones, and a full 23/24 bit
DCS encoder and decoder. The MX828 also provides a general purpose timer, a comparator with a programmable
threshold, and a summing amplifier with two adjustable gain blocks to facilitate design integration and reduce part count.
The MX828 may be used with a 3.0 to 5.5 volt supply and is available in the following packages: 24-pin SSOP
(MX828DS), 24-pin SOIC (MX828DW), and 24-pin PDIP (MX828P).
© 1997 MX•COM Inc.
www.mxcom.com Tele: 800 638-5577 336 744-5050 Fax: 336 744-5054
Doc. # 20480161.002
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA
All trademarks and service marks are held by their respective companies.
CTCSS/DCS/SelCall Processor
2
MX828 PRELIMINARY INFORMATION
CONTENTS
Section
Page
1. Block Diagram .................................................................................................................................. 3
2. Signal List ......................................................................................................................................... 4
3. External Components ...................................................................................................................... 5
4. General Description ......................................................................................................................... 6
4.1 Software Description ................................................................................................................................. 7
4.2 8-bit Write Only Registers ........................................................................................................................ 8
4.3 16-bit Write Only Registers ...................................................................................................................... 9
4.4 Write Only Register Description ............................................................................................................... 10
4.5 8-bit Read Only Registers ....................................................................................................................... 16
4.6 Read Only Register Description............................................................................................................... 16
5. Application Notes............................................................................................................................ 20
5.1 General .................................................................................................................................................... 20
5.2 Transmitters ............................................................................................................................................. 20
5.3 Receiver (CTCSS/SelCall Decoder) ........................................................................................................ 21
5.4 Receiver (CTCSS Fast/Predictive Detector) ............................................................................................ 21
5.5 Receiver (DCS Decoder) ......................................................................................................................... 21
5.6 General Purpose Timer (GPT) ................................................................................................................. 21
5.7 Full Duplex Modes ................................................................................................................................... 21
6. Performance Specification............................................................................................................. 26
6.1 Electrical Performance ............................................................................................................................. 26
6.2 Timing Diagrams ...................................................................................................................................... 31
6.3 Packaging ................................................................................................................................................ 32
MX•COM, Inc. reserves the right to change specifications at any time and without notice.
© 1997 MX•COM Inc.
www.mxcom.com Tele: 800 638-5577 910 744-5050 Fax: 910 744-5054
Doc. # 20480161.002
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA
All trademarks and service marks are held by their respective companies.
CTCSS/DCS/SelCall Processor
3
MX828 PRELIMINARY INFORMATION
1. Block Diagram
R7
R6
C3
R2
TX AUDIO
OUT
CTCSS TX TONE
GENERATOR
SELCALL TX TONE
GENERATOR
DCS CODE
GENERATOR
TX TONE
TX SUB
AUDIO
OUT
RX
AUDIO
OUT
SUM
IN
SUM
OUT
MOD 1
IN
MOD 1
SUMMING
AMP
-
+
MOD 1
ENABLE
TRIM
CTCSS / DCS / SELCALL TX
VSS
C4
C6
23 / 24 bits
V
BIAS
MOD 2
VBIAS
VDD
GENERAL PURPOSE
TIMER
TRIM
MOD 2
ENABLE
COMMAND DATA
C - BUS
INTERFACE
AND
CONTROL
LOGIC
REPLY DATA
CS
IRQ
SERIAL CLOCK
R5
V
DD
AUDIO BPF
AUDIO RX
6dB
ATTENUATOR
R3
RX AMP OUT
CTCSS / DCS / SELCALL RX
ADC
C5
R4
Input from
Demodulator
C7
RX AMP IN
-
+
SUB AUDIO
LPF
DCS
EQUALIZER
FILTER
COMPARATOR
3-bit
DAC
ADC
CTCSS/SELCALL
TONE
DECODER
VBIAS
RX AMP
ADC
DCS
DECODER
CTCSS
FAST TONE
DETECTOR
XTAL/CLOCK
C1
C2
X1
R1
XTAL
COMPIN
Figure 1: Block Diagram
© 1997 MX•COM Inc.
www.mxcom.com Tele: 800 638-5577 336 744-5050 Fax: 336 744-5054
Doc. # 20480161.002
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA
All trademarks and service marks are held by their respective companies.
+
CBUS
-
CLOCK
OSCILLATOR
AND
DIVIDERS
TX TONE
A/D CAP2
C9
CTCSS
PREDICTIVE
TONE DETECTOR
COMPOUT
A/D CAP1
C8
CTCSS/DCS/SelCall Processor
4
MX828 PRELIMINARY INFORMATION
2. Signal List
Pin No.
1
2
3
4
Name
XTAL
XTAL/CLOCK
SERIAL CLOCK
COMMAND DATA
Type
output
input
input
input
Description
The inverted output of the on-chip oscillator.
The input to the on-chip oscillator, for external Xtal circuit or clock.
The “C-BUS” serial clock input. This clock, produced by the µC, is used for
timing transfer of commands and data to and from the device. (Figure 4).
The “C-BUS” serial data input from the µC. Data is loaded into this device
in 8-bit bytes, MSB (B7) first, and LSB (B0) last, synchronized to the
SERIAL CLOCK. (Figure 4).
The “C-BUS” serial data output to the µC. The transmission of REPLY
DATA bytes is synchronized to the SERIAL CLOCK under the control of the
CS input. This 3-state output is held at high impedance when not sending
data to the µC. (Figure 4).
The “C-BUS” data loading control function: this input is provided by the µC.
Data transfer sequences are initiated, completed or aborted by the CS
signal (Figure 4).
This output indicates an interrupt condition to the µC by going to a logic "0".
This is a "wire-ORable" output, enabling the connection of up to 8
peripherals to 1 interrupt port on the µC. This pin has a low impedance
pulldown to logic "0" when active and a high-impedance when inactive. An
external pullup resistor is required.
The conditions that cause interrupts are indicated in the IRQ FLAG register
and are effective if not masked out by a corresponding bit in the IRQ MASK
register.
The output of the comparator.
The input to the comparator.
An internal reference voltage for the CTCSS A/D. Bypassed to V
SS
with an
external capacitor.
An internal reference voltage for the DCS A/D. Bypassed to V
SS
with an
external capacitor.
Negative supply (ground).
A bias line for the internal circuitry, held at V
DD
/2. This pin must be
bypassed by a capacitor mounted close to the device pins.
The inverting input to the Rx input amplifier.
Output of the Rx input amplifier
Output of the Rx audio filter section.
Output of the SelCall tone generator.
Input to the audio summing amplifier.
Output of the audio summing amplifier.
Input to MOD1 audio gain control.
Output of the CTCSS or DCS Tx tone generator.
Output of MOD1 audio gain control.
Output of MOD2 audio gain control.
Positive supply. Levels and voltages are dependent upon this supply. This
pin should be bypassed to V
SS
by a capacitor.
Table 1: Signal List
5
REPLY DATA
output
6
CS
input
7
IRQ
output
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
COMPOUT
COMPIN
A/D CAP 1
A/D CAP 2
V
SS
V
BIAS
RX AMP IN
RX AMP OUT
RX AUDIO OUT
TX AUDIO OUT
SUM IN
SUM OUT
MOD1 IN
TX SUB AUDIO OUT
MOD1
MOD2
V
DD
output
input
output
output
Power
output
input
output
output
output
input
output
input
output
output
output
Power
© 1997 MX•COM Inc.
www.mxcom.com Tele: 800 638-5577 336 744-5050 Fax: 336 744-5054
Doc. # 20480161.002
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA
All trademarks and service marks are held by their respective companies.
CTCSS/DCS/SelCall Processor
5
MX828 PRELIMINARY INFORMATION
3. External Components
XTAL
X1
R1
XTAL/CLOCK
C1
C2
V
DD
V
DD
XTAL
XTAL/CLOCK
SERIAL CLOCK
COMMAND DATA
REPLY DATA
CS
IRQ
COMPOUT
COMPIN
A/D CAP1
A/D CAP2
V
SS
C8
C9
1
2
3
4
5
6
7
8
9
10
11
12
24
23
22
21
20
19
18
17
16
15
14
13
C6
V
DD
MOD2
MOD1
TX SUB AUDIO OUT
MOD1 IN
SUM OUT
SUM IN
TX AUDIO OUT
RX AUDIO OUT
RX AMP OUT
RX AMP IN
V
BIAS
V
SS
"C-BUS"
INTERFACE
R5
MX828
R6
C3
R2
R7
R3
C5
C4
R4
C7
Input from
Demodulator
Figure 2: Recommended External Components
R1
R2
R3
R4
R5
R6
R7
C1
C2
Note 2
1M:
100k:
100k:
22k:
Note 1
Note 1
22pF
22pF
±5%
±10%
±10%
±10%
±10%
±10%
±10%
±20%
±20%
C3
C4
C5
C6
C7
C8
C9
X1
Note 3
Note 2
100pF
0.1µF
100pF
0.1µF
0.1µF
1.0µF to 3.3µF
4.032MHz
±20%
±20%
±20%
±20%
±20%
±20%
±20%
±100ppm
Table 2: External Components
© 1997 MX•COM Inc.
www.mxcom.com Tele: 800 638-5577 336 744-5050 Fax: 336 744-5054
Doc. # 20480161.002
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA
All trademarks and service marks are held by their respective companies.
