CH1794A Cermetek Microelectronics, CH1794A Datasheet - Page 6

• Manufacturer Part Number: CH1794A
• Manufacturer: Cermetek Microelectronics

Specifications of CH1794A

• Lead Free Status / RoHS Status: Not Compliant

Cermetek Microelectronics, Inc.
This feature is available only with a connection to an
ISP server supporting MOH. MOH can be executed
using the +PMH and +PCW commands.
Cermetek document AT Commands and S-Registers,
for more details.
Quick Connect. The Quick Connect feature enables
the CH2056A modem to shorten the connect time of
subsequent calls to an ISP server supporting quick
connect. The Quick Connect feature is controlled via
the +PQC command.
PCM Upstream. PCM Upstream boosts the upstream
data rates between the CH2056A and the ISP by
reducing the upload times for large files and email
attachments. A maximum of 48kbps upstream rate is
supported with PCM Upstream enabled, in contrast to
a maximum of 32.2kbps upstream rate with PCM
Upstream not enabled. PCM Upstream is controlled
via the +PCM command. PCM Upstream is disabled
by default.
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
5 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.
2007 Cermetek Microelectronics, Inc.
Modem-on-Hold, Quick Connect and PCM Upstream
are only available with the CH2056A modems in
V.92 mode.
NOTE
Refer to
Page 6
The HS modem will stay off-hook with its carrier on
after the escape sequence is received.
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:
Result:
AT [Commands]<CR>.
Where: AT represents attention sequence. A and T
Where: <CR> represents carriage return (ASCII 13 or
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.
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.
<CR><LF> (Verbose)
CH179XA/2056A High Speed Family of Ultra Small Modems
may be either upper or lower case but must be
the same case.
command strings.
HEX 0D)
<LF> represents line feed (ASCII 10 or HEX
0A)
or
OK
ATDT1234567<CR>
Modem goes off-hook and tone dials phone
number 1234567.
Document No. 607-0020 Revision B (01/07)
WARNING
[Command] represents
The HS