DE8681
CML Microcircuits
COMMUNICATION SEMICONDUCTORS
UM8681/3 January 2004
V.22bis User Manual
for a "socket modem"
Provisional Issue
1.0
Features
•
PC Controlled via Terminal Emulator
•
FCC68 or CTR21 DAA
•
Single 3V or 5V dc power supply
operation
•
Break-off PCB sections
•
Supplied with PCB layout data
•
CMX868-based socket modem Reference Design
•
Fully Isolated 2-Wire Line Interface
•
Opto Isolated Ring Detect Circuitry and
OptoMOS Hook Relay
•
‘AT’ Command Compatible Firmware
•
On-board FLASH PIC Microcontroller
1.1
Brief Description
The DE8681 Demonstration Board is a reference design for the CMX868 V.22 bis modem IC. On the
main "socket modem" section it also contains the line interface components and a Flash PIC
µC.
Attached to the main section are two break-off sections which contain a 9-pin D type socket for PC serial
communications, a Flash PIC programming connector, an RJ11 line connector and various LEDs for
indicating signal activity. AT Commands are used to control the demonstration board via a standard
terminal emulator program running on a host PC.
Interfacing to the Demonstration Board can be via socket pins on the socket modem section, or via the
connectors provided on the break-off sections. The board can be operated at 3V or 5V dc, which must be
provided by an external, regulated power supply.
The PCB has been laid out for both CTR21 and FCC68 compliant DAA designs. However the
components fitted are for the simplified FCC68 design. Instructions are given for users who wish to fit
the CTR21 components. Hardware has been provided on the socket modem section for CLI Type 1, but
a PIC firmware upgrade will be required to enable this function, which may be available at a later date.
With this is mind, the socket modem has been provided with a Flash PIC Microcontroller that can be
serially programmed in circuit via the RS232 connection.
©
2004 CML Microsystems Plc
1
UM/8681/3
CMLMICRO [ CML MICROCIRCUITS ]
