CMX969
RD-LAP/MDC4800
Motient/
ARDIS
D/969/5
April 2001
Provisional Information
Features
•
•
•
•
Applications
•
•
•
•
•
Autonomous Frame Sync Detection
for SFR operation
Full Packet Data Framing
Low Power, 3.0 to 5.5V operation
Powersave Option
DataTAC*, Motient/ARDIS*, Dual
Mode RD-LAP* and MDC 4800
Two-Way Paging Equipment
Mobile Data Systems
Wireless Telemetry
*
DataTAC Terminals
*Radio Data-Link Access Procedure (RD-LAP) is a data communications air interface protocol developed by Motorola Inc.
*Motient is a registered service mark of the Motient Company operating the Motient Network. (Formerly known as American Mobile
operating the ARDIS Network).
*DataTAC is a registered trademark of Motorola Inc.
1.1
Brief Description
The CMX969 is a CMOS integrated circuit that contains all of the baseband signal processing and Medium
Access Control (MAC) protocol functions required for a high performance DataTAC dual mode (RD-LAP
19200 bps and MDC 4800 bps) FSK Wireless Packet Data Modem suitable for use with the Motient/ARDIS
network. It interfaces with the modem host processor and the radio modulation/demodulation circuits to
deliver reliable two-way transfer of the application data over the wireless link.
The CMX969 assembles application data received from the host processor, adds forward error correction
(FEC) and error detection (CRC) information and interleaves the result for burst-error protection. After adding
symbol and frame synchronisation codewords and channel status symbols, it converts the packet into a
filtered analogue baseband signal for modulating the radio transmitter.
In receive mode, the CMX969 performs the reverse function using the analogue baseband signals from the
receiver frequency discriminator. After error correction and removal of the packet overhead, the recovered
application data is supplied to the host processor. Any residual uncorrected errors in the data will be flagged.
A readout of the received signal quality is also provided.
An optional Autonomous Frame Sync Detection function is provided for use in Motient/ARDIS systems
employing Single Frequency Re-use operation.
The CMX969 uses signal filtering, data block formats and FEC/CRC algorithms compatible with the MDC and
RD-LAP over-air standards. The device is programmable to operate from a wide choice of Xtal frequencies
and is available in 24 pin DIP, SSOP and TSSOP packages.
©
2001
Consumer Microcircuits Limited
RD-LAP/MDC4800 Motient/ARDIS
CMX969
CONTENTS
Section
1.0
1.1
1.2
1.3
1.4
1.5
Page
Features and Applications.......................................................................1
Brief Description .......................................................................................1
Block Diagram ...........................................................................................3
Signal List...................................................................................................4
External Components ...............................................................................5
General Description ..................................................................................6
1.5.1 Description of Blocks..................................................................6
1.5.2 Modem - µC Interaction...............................................................8
1.5.3 Binary to RD-LAP 4-Level Symbol Translation .......................9
1.5.4 Frame Structure .........................................................................10
1.5.4.1 MDC Mode...................................................................................10
1.5.4.2 RD-LAP Mode .............................................................................11
1.5.5 The Programmer's View ............................................................12
1.5.5.1 Data Block Buffer.......................................................................12
1.5.5.2 Control Register.........................................................................12
1.5.5.3 Mode Register ............................................................................13
1.5.5.4 Command Register ....................................................................15
1.5.5.5 Status Register...........................................................................26
1.5.5.6 Data Quality Register ................................................................28
Application Notes....................................................................................29
1.6.1 Autonomous Frame Sync Detect Function............................29
1.6.2 Rx Control Procedure................................................................30
Performance Specification.....................................................................32
1.7.1 Electrical Performance..............................................................32
1.7.1.1 Absolute Maximum Ratings .....................................................32
1.7.1.2 Operating Limits.........................................................................32
1.7.1.3 Operating Characteristics ........................................................33
1.7.2 Packaging....................................................................................36
1.6
1.7
©
2001
Consumer Microcircuits Limited
2
D/969/5
RD-LAP/MDC4800 Motient/ARDIS
CMX969
1.2
Block Diagram
Figure 1 Block Diagram
©
2001
Consumer Microcircuits Limited
3
D/969/5
RD-LAP/MDC4800 Motient/ARDIS
CMX969
1.3
Package
P4/E2/D5
Pin No.
1
Signal List
Signal
Name
IRQN
Type
O/P
A 'wire-ORable' output for connection to the host
µ
C's Interrupt
Request input. This output has a low impedance pull down to V
SS
when active and is high impedance when inactive. An external pull
up resistor of about 100k ohm to V
DD
is required.
)
)
)
)
)
)
)
)
Description
2
3
4
5
6
7
8
9
10
D7
D6
D5
D4
D3
D2
D1
D0
RDN
BI
BI
BI
BI
BI
BI
BI
BI
I/P
8-bit bidirectional 3-state
µ
C interface data
lines.
Read. An active low logic level input used to control the reading of
data from the modem into the host
µ
C.
Write. An active low logic level input used to control the writing of
data into the modem from the host
µ
C.
The negative supply rail (ground).
Chip Select. An active low logic level input to the modem, used to
enable a data read or write operation.
)
)
Two logic level modem register select
inputs.
11
WRN
I/P
12
13
Vss
CSN
Power
I/P
14
15
16
17
18,19
A0
A1
XTALN
XTAL
I/P
I/P
O/P
I/P
NC
The output of the on-chip oscillator.
The input to the on-chip oscillator, for external Xtal circuit or clock.
No connection should be made to these pins (reserved for possible
future use)
The Tx signal output from the modem.
A bias line for the internal circuitry, held at ½ V
DD
. This pin must be
decoupled to V
SS
by a capacitor mounted close to the device pins.
The input to the Rx input amplifier.
20
21
TXOP
V
BIAS
O/P
O/P
22
RXIN
I/P
©
2001
Consumer Microcircuits Limited
4
D/969/5
RD-LAP/MDC4800 Motient/ARDIS
CMX969
Package
P4/E2/D5
Pin No.
23
24
Signal
Name
RXFB
V
DD
Type
O/P
Power
Description
The output of the Rx input amplifier .
The positive supply rail. Levels and voltages are dependent upon
this supply. This pin should be decoupled to V
SS
by a capacitor.
Notes:
I/P = Input
O/P = Output BI = Bidirectional NC = No connection
Internal protection diodes are connected from each signal pin to V
DD
and V
SS.
1.4
External Components
Figure 2 Recommended External Components
R1
R2
R3
R4
X1
See Section 1.5.1
100k ohm
±
5%
1M ohm
±
20%
100k ohm
±
5%
4.9152, 7.3728 or 9.8304 MHz ±100ppm. See Section 1.5.5.2
C1
C2
C3
0.1 µF
±
20%
0.1 µF
±
20%
±
20%, see Note 1
C4
C5
C6
±
20%, see Note 1
100pF
±
5%
100pF
±
5%
Note 1: The values used for C3 and C4 should be suitable for the frequency of the crystal X1. As a
guide, values (including stray capacitances) of 33pF at 1MHz falling to 18pF at 10MHz will generally
prove suitable.
©
2001
Consumer Microcircuits Limited
5
D/969/5
嵌入式系统
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
