CH1786LC Cermetek Microelectronics, CH1786LC Datasheet - Page 9

• Manufacturer Part Number: CH1786LC
• Manufacturer: Cermetek Microelectronics

Specifications of CH1786LC

• Main Category: Single Chip
• Data Rate: 2.34375Kbps
• Power Supply Type: Analog
• Operating Supply Voltage (typ): 5V
• Operating Supply Voltage (min): 4.75V
• Operating Supply Voltage (max): 5.25V
• Operating Temp Range: 0C to 70C
• Operating Temperature Classification: Commercial
• Mounting: Through Hole
• Lead Free Status / RoHS Status: Supplier Unconfirmed

Cermetek Microelectronics, Inc.
AT COMMAND APPLICATIONS
Dialing A Phone Number. The Dial command takes
the form Dn, where n is a string of characters. In the
simplest form, n will be only the digits of the phone
number to be dialed.
Example: Tone Dial number.
Enter:
Result:
In response to this command, the CH1786 dials the
telephone number “123-4567” and then waits for a
carrier from the distant modem.
detected within a given time (the default time is 30
seconds), the CH1786 automatically releases the line
and sends a NO CARRIER result code. If a carrier is
detected, the CH1786 gives a CONNECT result code
and goes on-line, permitting communication with the
distant modem.
The Dial Command may also be issued without a
telephone number. ATD causes the modem to pick
up the telephone line without dialing a number.
Pause During Dialing. When placing a call from an
office with a telephone connected to a PBX, it may be
necessary to dial an access code (usually the digit 9)
to get an outside line.
telephone number instructs the modem to pause for a
specific length of time. The factory set default pause
time is 2 seconds.
Example: Pulse Dial 9,pause, dial number.
Enter:
Result:
Multiple commas may be used to generate integer
multiples of the specified delay time.
Originate a Call in Answer Mode. The D command
forces the modem into originate mode. To call an
originate-only modem, dial the number and set the
modem to answer mode via the R command (reverse
originate). This is done by including an R at the end
of the telephone number.
Example: Change
Enter:
Result:
Multiple commas may be used to generate integer
multiples of the specified delay time.
Redial Last Number.
convenient way to execute the previously entered
command line.
2004 Cermetek Microelectronics, Inc.
ATDP9,1234567<CR>
OK
answer mode.
ATDT1234567R<CR>
OK
ATD1234567<CR>
OK
modem
The repeat command is a
Inserting a comma in the
from
original-only
If no carrier is
to
Page 9
Example: Use A/, the repeat command, to redial the
last telephone number dialed.
Enter:
Result:
Return to Command State.
command mode offer dialing.
Example: Touch-tone dial 9, pause, dial number,
return to Command.
Enter:
Result:
Automatic Answering. The SO register controls the
number of rings that must occur before the modem
answers a call. The register may range in value from
0 to 255.
S0 =
S0 =
S0 =
S0 =
S0 =
When S0 is set to 0, the modem will not auto-answer.
The Serial Interface Lines. The CH1786 supports a
full EIA-232D/V.24 serial interface. Signal levels are
TTL rather than EIA-232D level compatible, which
allows direct connection of the CH1786 to the host
UART without the need for level translation circuitry.
See Table 2 for a complete pin description.
The CH1786 is controlled by sending it serial
commands over TXD and its status determined by
monitoring the serial status messages returned on
RXD. DTR is optionally used to reset, terminate calls
or return CH1786 to command mode.
All other serial interface lines may be utilized for the
convenience of a particular application but are not
required by the CH1786.
modem) should be left unconnected. Unused inputs
should be set to the proper logic level. See Table 2.
Fax Modes. The CH1786 Product Family supports
Send and Receive FAX. The modes and rates are
determined by the AT+F commands. Refer to Table
6A.
FAX modem processing is explicitly defined in ITU-U
V.29, ITU-U V.27, and ITU-U V.21 recommendations.
All modulation, wave-form spectrum, and data
processing functions conform to the appropriate
specifications.
0 DO NOT ANSWER TELEPHONE
1 ANSWER ON RING 1
2 ANSWER ON RING 2
3 ANSWER ON RING 3
255 ANSWER ON RING 255
A/
ATDT1234567R<CR> Previous command
OK
ATDT9,1234567;<CR>
OK
CH1786 Family of Ultra Small 2400bps Modems
Document No. 607-0004 Revision L4 (08/04)
Unused outputs (from
line executed
Use ; to return to