V.22 bis Modem with AT Commands
CMX866
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
Bn, &Gn
S2, S3, S4, S5, S10,
S23, S24, S27
· Set modem line communication functions, software protocol
and control characters for AT commands
Nn
S24
· Select automatic or no fallback from V.22bis to V.22
· Select V.23 or Bell 202 fast turnaround
RO
S14, S24
· Return to Command mode by:
S12
S24
S14
S28
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)
S14
· 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
@Rn, @RR,
@F8
· Detect dual alert tones or FSK whilst on-hook (for Type 1 CLI)
&Z0, &Z1
S21
· 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
&Tn
S15, S16, S18, 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
Dn, DTn, DL, S6, S7, S8, S11,
· Automatically dial a directory number and monitor call
Hn, Xn
S22, S29
progress tones before entering the modem function
A, Hn
S0, S1, S17
S25, S26
· Automatically answer an incoming call
· Independently set the Rx and Tx path gain
In, &V
· Perform internal confidence tests on the CMX866 and report
back the device revision, status and configuration
A/, En, Qn,
Vn
S14
S24
· Perform miscellaneous line communications functions, such as
repeating the last command, selecting alphabetic or numeric
result codes, etc.
Z
· Restore the default 'factory profile', placing the CMX866 into a
known state without resetting the device
&Cn, &Dn
O, RO, &Tn
· Set the serial interface (RS232) communications protocol and
CMX866 hardware configurations
· Enter Data mode from Command mode
ã 2004 CML Microsystems Plc
16
D/866/4
CMLMICRO [ CML MICROCIRCUITS ]
