Cermetek Microelectronics, Inc.
High Speed Modem and FAX Family
2003 Cermetek Microelectronics, Inc.
Page 5
Document No. 607-0003 Revision K3 (09/03)
2. To switch to data mode, switch local voice source
from T1:
(a) At the Originate Modem, enter:
ATX1<CR>
(b) At the Answer Modem, enter:
ATA<CR>
3. To disconnect (hang-up) a voice call or data call:
(a) Return to control mode by entering:
+++
(b) Enter:
ATH<CR>
4. To place a voice call using the HS Modem DTMF
facilities:
(a) Enter:
ATDT1234567<CR>
Where
1234567
is the phone number
(b) Then switch to local voice source
MODEM CONTROL
The HS Modem may be controlled by sending serial
ASCII command sequences. The commands are sent
to the modem serially on the TXD pin. After execution
of a received command, the modem returns a serial
status message that completion status. Refer to Table
5A, 5B and 5C for a complete list of status messages.
MODEM STATES
The HS Modem can be in either command mode or
data mode. When the modem is idle, it is in command
mode by default and will recognize commands. When
data transmission is in progress, the HS modem is in
the data mode state and will not recognize commands.
To force the HS Modem to recognize commands, the
host must send an “escape sequence” to the HS
Modem forcing it out of data mode and into command
mode.
The escape sequence consists of a “guard time” (a
period where no characters are sent to the modem),
followed by 3 escape characters, followed by a second
guard time. At power-up, the guard time is set to 1
second, and the escape character is set as ”+.” Note
that a 50 msec delay is required between escape
characters. These two parameters can be modified
via registers S2 and S12, respectively.
The HS modem will stay off-hook with its carrier on
after the escape sequence is received. The HS
Modem will return an OK status message when it is
ready to accept commands. To put the HS Modem
back into data mode, issue command
ATO<CR>
.
THE COMMAND FORMAT
HS Modem commands consist of three elements:
1. The
attention
sequence,
2. The commands themselves and
3. A terminating carriage return.
Enter:
ATDT1234567<CR>
Result: Modem goes off-hook and tone dials phone
number 1234567.
WARNING
The HS Modem family of products has been FCC
Part 68 approved as data/FAX modems. Utilization
of the Voice/Tone Port requires further registration.
The FCC requires that the entire system, including
the HS Modem and the handset or DTMF
transceiver, adhere to Part 68 rules.
Figure 4. HS Modem Family Application Diagram.
RXD
DCD
DSR
RI
CTS
TXD
DTR
+5V
GND
V.24
EIA-232-E
INTERFACE
OR
UART
TIP
RING
RJ-11
JACK
SPK
SPEAKER
CONTROL
NOTE: SPEAKER CONTROL AND PHONE
CONTROL ARE ANCILLARY CIRCUITS
SHOWN ELSEWHERE IN THIS DATA SHEET.
HS MODEM
FAMILY
ANALOG VOICE
INJECTED SIGNALS
T1
EXTERNAL RESET
RST
*
SIGNAL GND MUST BE CONNECTED TO
EARTH GROUND
Vcc
Isolated
Envelope
Ring Detect
4.7uF
Vcc
10K
4.7K
22K
10K
.1uF
+
-
-
+
LM393
LM393
1
2
3
4
5
6
7
8
RI
