CH2100 데이터 시트보기 (PDF) - Cermetek Microelectronics
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CH2100 Datasheet PDF : 10 Pages
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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 another guard time. At powerup, the guard
time is set to 1 second minimum, and the escape character is set
as “+.” These two parameters can be modified via registers S12
and S2, respectively.
The CH2100 will stay off-hook with its carrier on after the escape
sequence is received and it returns an OK status message when
it is ready to accept commands. The CH2100 can be put into data
mode by issuing the command ATO [CR].
AT COMMAND APPLICATIONS
Dialing A Phone Number.
The Dial command takes the form Dn, where n is a string of char-
acters. In the simplest form, n will be only the digits of the phone
number to be dialed.
Example: Dial number.
Enter: AT D1234567
Return to Command State.
The modem can be forced to reenter the command state after
dialing (without hanging up) by ending the dial command with a
semicolon. This is useful when using the modem as an auto
dialer.
Example: Touch-tone dial 9, pause, dial number, return for
command.
Enter: AT DT9, 1234567;
Result: OK
Automatic Answering.
The S0 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 = 0
DO NOT ANSWER TELEPHONE
S0 = 1
ANSWER ON RING 1
S0 = 2
ANSWER ON RING 2
S0 = 3
ANSWER ON RING 3
S0 = 255
ANSWER ON RING 255
When S0 is set to 0, the modem will not auto-answer.
In response to this command, the CH2100 dials the telephone
number “123-4567” and then waits for a carrier from the distant
modem. If no carrier is detected within a given time (the default
time is 30 seconds), the CH2100 automatically releases the line
and sends a NO CARRIER result code. If a carrier is detected, the
CH2100 gives a CONNECT result code and goes on-line, permit-
ting communication with the distant modem.
The Dial Command may also be issued without a telephone num-
ber. 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. Inserting a comma in the telephone
number instructs the modem to pause for a specific length of time.
The factory set default pause time is 2 seconds.
Example: Dial 9, pause, dial number.
Enter: AT DT9, 1234567
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 modem from original-only to answer mode.
Enter: AT DT 1234567R
Redial Last Number.
Use A/, the repeat command, to redial the last telephone number
dialed.
CONNECTING TO THE HOST UART
Since the CH2100 communicates data serially and most host
products handle data in a parallel format, a UART is needed to
make parallel-to-serial and serial-to-parallel translations.
The modem is controlled by sending it serial commands over TXD
and can be monitored by serial status messages returned on
RXD. RI is optionally used to monitor the ring signal.
PHONE LINE CONNECTION GUIDELINES
1) The CH2100 must be mounted in the final assembly such
that it is isolated from exposure to any hazardous voltages
within the assembly. Adequate separation and restraint of
cables and cords must be provided.
2) The circuitry from the CH2100 to the telephone line interface
must be provided in wiring that carries no other circuitry other
than that specifically allowed in the FCC rules (such as A and
A1 leads).
3) Connection to phone line should be made through an RJ-11
jack.
4) PCB traces from the modem’s RING and TIP pins to the RJ-11
jack must be 0.1 inch spacing or greater to one another and
0.2 inch spacing or greater to all other traces. The traces
should have a nominal width of 0.020 inches or greater.
5) The RING and TIP PCB traces should be as short as possible
and oriented to prevent coupling other high speed or high
frequency signals present on the host circuit PCB.
6) No additional circuitry other than that shown in Figure 3 may
be connected between the modem module and the RJ-11
jack. Doing so will invalidate the FCC approval.
7) The CH2100, the RJ-11 jack, the interfacing circuitry and all
PCB traces in between, must be contained on a PCB with a 94
V-0 flammability rating.
8) The supplied FCC registration label must be applied visibly
on the outside of the product.
9) The product’s User Manual must provide the user with instruc-
tions for connection and use as recommended in the FCC
Registration Section below.
1999 Cermetek Microelectronics, Inc.
Document No. 607-2100 Rev.D (8/99) 5
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