CH1786LC Cermetek Microelectronics, CH1786LC Datasheet - Page 5

• 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.
Reset.
CH1786 automatically generates an internal reset
pulse. The user may also reset the modem externally
by applying a high-going reset pulse to the RST pin
for at least 10ms after the +5V power supply has
stabilized. Delay sending commands to CH1786 for
200ms after reset has been initiated to allow the
CH1786 time to properly reconfigure.
Training the Modem. Each modem must be trained
to match its host’s speed and parity so that it is able
to recognize serial asynchronous commands sent to it
by the host’s is UART. The host must retrain the
modem each time a reset pulse is applied on RST or
after a RESET serial command has been issued.
Modem Training Command Sequence.
CH1786 is trained by sending it the following
sequence:
Enter: AT<CR>
Result: OK
Where: A and T may be either upper or lower case
The AT sequence is referred to as an attention
sequence. The CH1786 will respond with one of the
following status messages, depending on whether it
is optioned for Terse (abbreviated) or Verbose
(English) status messages.
Result: 0<CR> (Terse)
Result:
Where:
After responding with an OK, the CH1786 is in idle
mode and is ready to accept additional commands.
An alternate attention sequence A/ may be sent
which behaves much like the AT sequence except
that it causes the previously entered command
specified with an AT prefix to be executed. When
given, both the AT and A/ must be in upper case
ASCII.
command.
THE COMMAND FORMAT
Typical commands consist of three elements: the
attention sequence, the commands themselves, and
a terminating carriage return.
AT[commands]<CR>.
Where: AT represents attention sequence.
2004 Cermetek Microelectronics, Inc.
but must be the same case.
<CR> represents carriage return
[Commands] represents command strings.
Upon applying power to the CH1786, the
No carriage return is needed for the A/
or
<CR><LF>OK<CR><LF> (Verbose)
<CR> represents carriage return (ASCII 13
or HEX 0D).
<LF> represents line feed (ASCII 10 or
HEX 0A).
The
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When entering commands to the modem, the
backspace character-control-H (ASCII 8 or HEX 08)
may be used to edit mistakes. AT and A/ may not be
edited.
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 CH1786
to configure itself to not echo characters when in
command mode E0 and then put itself in answer
mode A.
Enter: ATE0A<CR>
Result: OK
AT Command Set. The available command set is
divided into four types of commands: dial modifiers,
basic
commands. Refer to the complete list in Table 5.
AT Command Data Rate. With the serial interface,
the rate is speed sensed for parity and format.
THE STATUS MESSAGES
The CH1786 responds with a status message after
each command is executed. This status message
may either be a single digit followed by a carriage
return or a carriage return and line feed with a
message in English, followed by a carriage return and
line feed.
The basic status code subsets are enabled with the
Xn command.
result codes allowed by the user.
X0:
X1:
X2:
X3:
X4:
MODEM STATES
The CH1786 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 CH1786 is
in the data mode state and will not recognize
commands.
commands, the host must send an escape sequence
to the CH1786 forcing it out of data mode and into
command mode.
The CH1786 is factory set to X4, which allows all
result codes.
Result Codes 0, 1, 2, 3, 4 allowed
Result Codes 0, 1, 2, 3, 4, 5, 10 allowed
Result Codes 0,1, 2, 3, 4, 5, 6, 10 allowed
Result Codes 0, 1, 2, 3, 4, 5, 7, 10 allowed
Result Codes 0, 1, 2, 3, 4, 5, 6, 7, 10 allowed.
commands,
<CR> represents carriage return (ASCII 13
or HEX 0D).
Multiple commands may be placed in the
To force the CH1786 to recognize
CH1786 Family of Ultra Small 2400bps Modems
Where n=0,1,2,3,4 establishes the
Document No. 607-0004 Revision L4 (08/04)
NOTE
ampersand
and
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