CML Microcircuits CMX866, Manual, Page: 16 / 53

V.22 bis Modem with AT Commands CMX866
©
2008 CML Microsystems Plc 16 D/866/5
1.5.3 Functional Description
The CMX866 is a multi-functional integrated modem chip which requires simple telephone line and
RS232 interfaces to implement a complete, low-power modem that can be controlled by widely used AT
commands. A list of the main features of this product is given below:
Function Commands Registers
•
Set modem line communication functions, software protocol
and control characters for AT commands
Bn, &Gn S2, S3, S4, S5, S10,
S23, S24, S27
•
Select automatic or no fallback from V.22bis to V.22
Nn S24
•
Select V.23 or Bell 202 fast turnaround
RO S14, S24
•
Return to Command mode by:
1) Issuing an escape sequence: <delay> +++ <delay>
2) Taking the DTRN pin high (active low)
3) Taking the ESC pin high (active high)
4) Taking the RTSN pin high (active low)
S12
S24
S14
S28
•
Bypass the answertone detection sequence to give "Fast
Connect"
S14
•
Set modem into answer or originate mode, independently of
whether a call is being initiated or answered
S14
•
Detect dual alert tones or FSK whilst on-hook (for Type 1 CLI)
@Rn, @RR,
@F8
•
Place the CMX866 into either 'Zero-Power' or Powersave
states. When in these states, the CMX866 can be "woken-up"
by either:
1) activity on the DTRN pin (including transmitted data, if this
is also wired to the DTRN pin)
2) detection of a Ringing condition on the RD and RT pins
&Z0, &Z1 S21
•
Make local and remote digital loopback connections and allow
remote modems to digitally loopback the CMX866. This
facilitates the provision of loopback tests by the external host
µController
&Tn S15, S16, S18, S21
•
Automatically dial a directory number and monitor call progress
tones before entering the modem function
Dn, DTn, DL,
Hn, Xn S6, S7, S8, S11,
S22, S29
•
Automatically answer an incoming call
A, Hn S0, S1, S17
•
Independently set the Rx and Tx path gain
S25, S26
•
Perform internal confidence tests on the CMX866 and report
back the device revision, status and configuration
In, &V
•
Perform miscellaneous line communications functions, such as
repeating the last command, selecting alphabetic or numeric
result codes, etc.
A/, En, Qn,
Vn S14
•
Restore the default 'factory profile', placing the CMX866 into a
known state without resetting the device
Z
•
Set the serial interface (RS232) communications protocol and
CMX866 hardware configurations
&Cn, &Dn S24
•
Enter Data mode from Command mode
O, RO, &Tn