CH1787 데이터 시트보기 (PDF) - Cermetek Microelectronics

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CH1787

Small Footprint Hardware Controllable 2400bps Modem

Cermetek Microelectronics 

Cermetek Microelectronics, Inc.

The Dial Command may also be issued without a

telephone number. The ATD command causes the

modem to pick up the telephone line without dialing a

number.

Using the Pause Character. 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 directs the CH1787 to pause for a

specific length of time. The factory default pause time

is 2 seconds.

Example: Dial 9, pause, and dial number.

Enter:

ATDT9,1234567<CR>

Response: Dial tone, DTMF tone generation

Multiple commas may be used to increase delay time.

TOUCH TONE AND PULSE DIALING

The CH1787 can use DTMF (touch-tones) or dial

pulses when dialing a telephone number. If the dial

command does not specify which type to use, the

CH1787 defaults to the type last specified. The power-

on default value is P.

Example: Pulse dial 9, pause, and touch-tone dial

number.

Enter:

ATDP9T1234567<CR>

Response: Dial tone, Pulse dialing

Originate a Call in Answer Mode. The D command

forces the CH1787 into originate mode. To call an

originate-only modem, dial the number and set the

modem to answer mode via the R (reverse originate).

Enter the R command at the end of the telephone

number.

Redial Last Number. Use A/, the repeat command, to

redial the last telephone number dialed when a busy

signal is received.

Return to Command State. The CH1787 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 CH1787 as

an auto dialer.

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-

255.

Example: Touch-tone dial 9, pause, dial number,

return for command.

CH1787 Small Footprint Hardware Controllable 2400bps Modem

Table 2. CH1787 Register Summary.

Register Function

S0*

Ring to Answer On

S1

Ring Count

S2

Escape Code Character

S3

Carriage Return Character

S4

Line Feed Character

S5

Back Space Character

S6

Wait for Dial Tone

S7

Wait Time for Data Carrier

S8

Pause Time for Comma

S9

Carrier Detect Response Time

S10

Lost Carrier to Hang-up Delay

S11

DTMF Dialing Speed

S12

Escape Code Guard Time

S14* Bit Mapped options Register

S16

Modem test Options

S18* Test Timer

S21* Bit Mapped options Register

S22* Bit Mapped options Register

S23* Bit Mapped options Register

S24

Sleep Mode Inactivity Time

S25* Delay to DTR

S27* Bit Mapped options Register

S28* Bit Mapped options Register

*= S-Register stored in NVRAM upon receipt or & W

command.

Enter:

ATDT9,1234567;

Response: Dial tone, DTMF tones, return to Command

State

S0 DO NOT ANSWER TELEPHONE

S1 ANSWER ON RING 1

S2 ANSWER ON RING 2

S3 ANSWER ON RING 3

When S0 is set to 0, the modem will not auto-answer.

Example: assign the value 6 to S0 to set the CH1787

to answer on the sixth ring.

Enter:

ATS0=6<CR>

Response: OK

CONNECTING TO THE HOST UART

Since the CH1787 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 Serial Interface Lines. The CH1787 supports the

full RS-232C/V.24 serial interface. Signal levels are

TTL rather than RS-232C level compatible, which

allows the user to directly connect the CH1787 to the

host’s UART without needing level translating circuitry.

2002 Cermetek Microelectronics, Inc.

Page 7

Document No. 607-0002 Revision B (03/02)

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