CMX868 Reference Design and Demonstration Board
DE8681
1.3
Quick Start
This section provides instructions for users who wish to experiment immediately with the
demonstration board. A fuller description of the board and its use appears later in this document.
1.3.1
Setting-Up
THE DE8681 COMES PRE-CONFIGURED AS A FCC68 MODEM, USING THE CMX868
TSSOP DEVICE AND A PRE-PROGRAMMED FLASH PIC µC, FOR OPERATION AT 5.0
VOLTS.
See section 1.6 for the alternative component values required for 3.0V or CTR21
operation.
An RJ11 (US style) phone jack, J3, for 2-wire line connection is provided on one of the break-off
board sections. Power is connected via socket pins
61(VDD)
and
41(GND).
See pinout, figure 2.
Attach the 9-way RS232 cable between connector J4 and the serial port of the PC. Connect an
external modem/line simulator to the evaluation kit using a suitable RJ11 telephone cable (not
supplied).
The DE8681 is supplied with the break-off sections of the board intact. If a socket modem using
the industry standard footprint is required, detach these break-off sections from the
Demonstration Board PCB by using a suitable tool to scribe along the perforations that join the
break-off sections to the main PCB. Scribe on both top and bottom sides of the board and
ensure that the scribed line completely cuts any copper tracks entering or leaving the break-off
sections from the main PCB. When this is done, gently break-off the first section on which
connector J4 (9-pin D Type socket) is mounted, then break-off the second section on which the
RJ11 socket is mounted. All connections to the remaining socket modem must now be made
through the PCB connector pins.
1.3.2
Operation
The DE8681 demonstration board allows the user to perform calling, answering and simple data
transfer with a suitable simulator or external third party modem (not supplied).
The board is controlled by the AT command set described in Section 1.6.3, by running a terminal
emulator program on the host PC. A suitable emulator is the ‘HyperTerminal’ program, which
operates under Windows 95/NT systems. The DE8681 AT command set consists of Basic,
Extended and CML Specific commands.
The board has two modes of operation:
AT Command Mode
In this mode the command processor firmware is constantly checking to see if the user has typed
a valid AT command. When a valid command is received the firmware will execute that
command. While the firmware is operating in this mode, the user can instruct it to manually
answer a call, originate a call, go on/off hook, read/write to S-registers, issue CML specific AT
commands, and perform any number of other AT command functions.
The board always starts in AT Command mode after power is applied and board initialisation is
complete.
The CML specific AT commands allow the user to directly control the CMX868 device for
evaluation purposes. Note, customer modified CMX868 device registers will be overwritten when
Dial and Answer AT commands are executed.
©
2004 CML Microsystems Plc
5
UM8681/3
CMLMICRO [ CML MICROCIRCUITS ]
