CH1794 Cermetek Microelectronics, CH1794 Datasheet - Page 6

• Manufacturer Part Number: CH1794
• Manufacturer: Cermetek Microelectronics

Specifications of CH1794

• Lead Free Status / RoHS Status: Supplier Unconfirmed

Cermetek Microelectronics, Inc.
AT [Commands]<CR>.
Where: AT represents attention sequence. A and T
Where: <CR> represents carriage return (ASCII 13 or
HEX 0D)
The HS Modem will respond with one of the following
status messages depending on whether it is optioned
for abbreviated (terse) or English (verbose) status
messages.
Result: 0 <CR> (Terse)
Result: <CR><LF>
After accepting the AT<CR> command the HS modem
is in idle mode and is ready to accept additional
commands.
An alternate attention sequence A/ may be issued
which behaves much like the AT sequence except that
it causes the last entered command specified with an
AT prefix to be executed. When given, it must be in
upper case ASCII. No carriage return is needed for
this command.
When entering commands to the modem, the
backspace character-control-H (ASCII 8 or HEX 08)
can be used to edit mistakes. AT and A/ may not be
edited however. Multiple commands may be placed
on a command line. A command line may be as long
as 40 characters, excluding the letters AT. By way of
example, the command below instructs the HS Modem
to configure itself to not echo characters when in
command mode (E0) and then puts itself in answer
mode (A).
Enter: ATE0A<CR>
Result: OK<CR><LF>
AT Command Set. The available command set is
divided into four types of commands: dial modifiers,
basic commands, ampersand and percent commands.
Refer to the complete list in Tables 6A and 6B.
INITIALIZING THE MODEM
Before commands may be sent to the HS Modem, the
modem must be initialized. This is a two step process:
Step 1. Modem Reset.
2004 Cermetek Microelectronics, Inc.
may be either upper or lower case but must be
the same case.
command strings.
<LF> represents line feed (ASCII 10 or HEX
0A)
or
OK
<CR><LF> (Verbose)
applying a hardware-reset pulse to pin RST or
by switching the power off then back on.
This is accomplished by
[Command] represents
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Step 2. Initial Modem Training. The modem must be
HS Modem Reset. Upon applying power to the HS
Modem, the HS Modem automatically generates an
internal reset pulse.
modem externally by applying a high-going reset pulse
to the RST pin for at least 10 msec after the +5V
power
commands to the HS Mode for 2 seconds after reset
has been initiated to allow the HS Modem time to
properly reconfigure.
On power up, or when reset is initiated either by the
ATZ<CR> command or by the RST pin, the modem
will reconfigure to its default state with the line carrier
modulation speed set to:
1. 14.4kbps for the CH1794
2. 33.6kbps for the CH1799
3. 57.6kbps for the CH2056
If desired, any speed, error correction, or data
compression method available on the HS Modem can
be locked in, using the AT\Nn and/or AT+MS
commands.
Training the Modem. Each modem must be trained
to match the host DTE speed and parity so that it is
able to recognize serial asynchronous commands sent
to it by the DTE.
The DTE must retrain the modem each time a reset
pulse is applied on RST or after a RESET serial
command has been issued.
STATUS MESSAGES AND RESULTS CODES
A result code is issued by the HS Modem to the DTE
for all commands executed by the HS Modem except
dialing commands. Further, various activities on the
PSTN are also signaled to the DTE by the HS Modem.
All result codes have either a terse, short form version
(which is identified by a number followed by a <CR>)
or a verbose long form English-like message version
(which is preceded and terminated with a <CR> and
<LF>).
The user may suppress certain subsets of the non-
extended result codes.
selecting subsets of the result code set using the
ATXn command, where n=0, 1, 2 or 3. Optionally, the
user may specify an extended set of results codes
(codes above 35) by setting Register S95. See the
detailed description of results codes in Table 5A, 5B
and 5C.
All AT commands, other than dialing commands, will
be responded to with either an OK (short form result
trained to the host DTE speed and parity (odd,
even, mark, space or none). These activities
are briefly described below.
supply
has
Document No. 607-0003 Revision K6 (08/04)
stabilized.
The user can also reset the
High Speed Modem and FAX Family
This is accomplished by
Delay
sending