Cermetek iModem Series User manual

© 2000 Cermetek Microelectronics, Inc. 1 Document No. 607-0017 Rev. B (07/00)
HIGH SPEED INTERNET MODEM FAMILY
microelectronics
Cermetek CH2156
CH2157
CH2158
CH2159
CH2160
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-
-
-
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3 I/O Ports Send Email Only.
2 I/O Ports & Temp Sense. Send Email Only.
Send Serial Data to/from Internal RAM. Send Email Only.
Send/Receive Data Internal Cache 4MEG RAM memory
Send/Receive Data. Streaming Data Format
TECHNICAL AND OPERATIONAL OVERVIEW
The iModem® Family of products are pin for pin compatible with the
CH179X and CH2056 modem products. Referring to Figure 1, the
CH21XXiModem®Familyconsistsofanindustrialgradehighspeed
modem module and a mP controller with associated internal logic.
The mP controller and the logic provide all the functions required for
internet communication via standard PSTN telephone lines. The
iModem® utilizes TCP, IP, PPP, PAP, SMTP and POP3 internet
protocols.
The iModem® requires an external RJ11C jack for the PSTN line
connection. An optional CCITT V.24 serial interface is required
when host processor control of the iModem® is either required or
desired in the specific application.
The iModem® receives iNet AT® commands from the host
processor or receives an event status flag on the Send Email
Control Pin (Pin #6) and proceeds to dial up the local ISP, log on
to the Internet and authenticate and verify user ID and password,
and either send or receive email depending on the command/
status flag received. All received emails are presented on the
RS232 interface for possible further host processing and reten-
tion.
The send and receive email function may be aborted at any time
during the email activity by activating the Send Email Control Pin
(Pin #6). This will cause the iModem® to terminate the email
activity and revert to the idle state.
The CH2158/9 and CH2160 iModem® products contain 32K of
extended memory and, therefore, can store limited emails for
later re-transmission. However, to fully utilize the receive email
capability, the RS232 interface should be operational.
FEATURES
• Uses Point-to-Point Protocol (PPP) with Password
Authentication Protocol (PAP) to connect to the Internet.
• Uses TCP/IP and Simple Mail Transfer Protocol (SMTP) to
send emails.
• On Demand and event driven email transmission and
reception.
• Programmable using serial interface or using PSTN.
• Remote programming using PSTN.
• Supports V.90, V.34bis, V.34, V.32, V.22bis, V.22A/B,
V.23, V.21, Bell 212A and 103.
• Supports V.80 Synchronous operation.
• Error correcting: V.42 LAMP, MNP 2-4 and MNP10.
• Data Compression: V.42bis and MNP5.
• MNP10 Data throughout enhancement for cellular
operation.
• DTE serial interface with speeds up to 230.4kbps.
• Automative baud rate adaptability utilizing speed
sensing, flow control and data buffers.
• Send & Receive FAX Class 1, Group 3 supported.
• Serial V.24, 5 volt interface.
• NVRAM directory and stored profiles.
• Standard AT Command structure with extensions.
• Cermetek iNet AT® Command extensions.
• Built-in DAA with 1500 VAC RMS isolation 2122V peak
surge protection.
• UL 1950 and CSA C22.2 950 (Third Edition) Listed,
Reference UL File E104957.
• FCC Part 68 Approved/DOT CSA CS-03 Part I
Approvable.
• Pin for Pin compatible with CH179X and HS Family of
modems.
• +5 Volt operation with zero power option.
• Small size: 1.35” x 1.97” x 0.61” (nominal).
TheiModem®s full range of capabilitiesandfeaturesallows forthree
methods of internet control as briefly described below.
Fully Autonomous On Demand and Event Driven Control.
This is the simplest method of operational control. Application of a
10ms TTL low going pulse (i.e., V<0.6) to the Send Email Control Pin
Each iModem®contains a fully functional 56kbps modem along
with the hardware and software needed to provide the internet
capability.
Because of this architecture, the iModem®has the unique ability to
operate as either an internet email transceiver or as simply a high
speed modem.
Additionally, the presence of the modem function allows for remote
access to reprogram or reconfigure the iModem® should the need
arise.
A validISPaccountIDandpasswordarerequiredtouse the internet
features. As a convenience to our customers, and to facilitate
operational use of the iModem®, Cermetek provides on an interim
basis a pre-programmed ISP account and password with each
iModem®delivered.
The iModem® Family is pin compatible with Cermetek’s HS Modem
familyand is FCCPart68approved and CanadianDOTapproveable.
The modules are designed for PCB throughhole mounting and are
1.35” x 1.97” x 0.61” in size.
INTRODUCTION
Cermetek’s iModem®Family of Internet products are the industries
first self contained modules providing a complete PSTN internet
communication solution. Further, the iModem® can operate
autonomously without the need for host processor intervention.
The iModem®Family offers a variety of internet communication
features ranging from simple on demand or event triggered email
transmission(CH2156)to full send and receive unlimited lengthemail
(CH2160). Internetcommunicationcontrolofthe iModem® exercised
by using one of the following basic control methods:
1. Fully Autonomous or event driven control requiring
no host processor intervention.
2. Semiautonomous control, requiring one command to be
issued from the host processor.
3. Complete host intervention and supervision.
Whenchoosingan implementation scheme utilizing a host processor,
the host controls the iModem® by issuing Cermetek iNet AT®
CommandswhichareextensionsofthestandardHayesAT command
set.

© 2000 Cermetek Microelectronics, Inc. Page 2 Document No. 607-0017 Rev. B (06/00)
Serial Host Interface Buffer.
The iModem® utilizes a serial V.24 EIA 232-E 5V interface to
control the modem and communicate with the mP.
Figure 1. Functional Block Diagram of iModem®
The internal modem can be controlled with industry standard AT
commands and is compatible with available industry communica-
tion software.
Modem Control.
DESCRIPTION OF FUNCTIONAL BLOCKS AND DISCUS-
SION OF BASIC OPERATIONS
Figure 1 contains a functional block drawing of the iModem®.
Host Supervised Control.
This method is the most flexible, but requires the issuance of each
of the necessary iNet® AT Commands in the required order from
the host processor.
Although the RS232 DTE serial interface is required to be opera-
tional for this method of control, an additional feature of this
method is the ability of the host to override the pre-programmed
ISP and/or email address by simply including the applicable
information on the same line of code as the iNet AT® Command.
Host supervised control is recommended for debug activities.
Regardless of the method of iModem® control employed, the
iModem® will abort all email related activities if a low going TTL
pulse is presented to the Send Email Control Pin (PIN #6) at any
time during or after initiation of email send (@TD command) or
email Receive (@TG Command).
mm
mm
mP Controller.
The mP controller is a Motorola GP32 type controller with resident
internet protocol software and flash ROM. This controller
interprets the iNet AT® commands issued by the external host
processor or executes internal iNet AT® Command strings
depending on the iModem® control method employed by the
user.
Extended RAM.
Additional RAM is used as cache memory for the purpose of
email flow control and to facilitate transmission and reception of
large email files.
Control of the internet capabilities of the iModem® can be either
event driven, semiautonomous, or initiated and controlled by a
system level host processor.
Further, the iModem® can function as a 56K V.90 modem when
not connected to the internet.
Semiautonomous control is a special case of full Host Supervised
Control and relies on the pre-programmed default internet configu-
ration profile contained within the iModem®. Initiation of the email
activity occurs with the issuance of either the @TD iNet AT®
Command (to Deliver email) or the @TG command (to receive
email) by the host processor to the iModem®. PSTN dial-up, logon
& authentication and email transmission are performed automati-
cally by the iModem® in the same fashion as the on Demand
control method described above.
Semi-Autonomous Control.
This method requires a minimal amount of host processor
intervention and by necessity requires that the RS232 DTE serial
interface be operational.
The iModem® performs the following functions automatically:
1. Connects to ISP.
2. Authenticates user ID and logs onto internet.
3. Sends (or Receives) email to address specified using ISPs
SMTP or POP3 Mail Server.
4. Terminates ISP session after all data is sent (or received).
5. Sends message accepted Pulse to Pin 4 after all the ISP Mail
Server accepts the email.
Each iModem® product consists of a mP controller with Network
Protocols and Flash ROM, Extended RAM (CH2158/9 or CH2160
only), serial interface buffer, modulator/demodulator, modem
controller with error correction and data compression, nonvolatile
RAM and DAA.
(Pin #6) will cause the iModem® to send an email using its internal
default internet configuration profile. This profile is pre-programmed
at the factory and can be modified by the user. No host processor
intervention is required. The RS232 DTE serial interface is not
required for fully autonomous on demand and event driven control.

© 2000 Cermetek Microelectronics, Inc. Page 3 Document No. 607-0017 Rev. B (06/00)
Typically this is accomplished by submitting the final end product
to an independent test house or consultant for evaluation. The
test/consultant then forwards the test results and applicable
documents to the regulatory agency. Contact Cermetek for a list
of suggested consultants.
Modulation/Demodulation/Error Correcting and Data
Compression
These functions are provided by an industry standard modem
ship set which has been adapted for use with the iModem®
Family.
Non-Volatile RAM (NVRAM).
NVRAM can store two user-customized configurations. The
AT&Wn command will store the active modem configuration in
one of two NVRAM locations as selected by an n of 0 or 1.
The modem communicates over the serial interface with the host
processor (referred to as a DTE or Data Terminal Equipment) at a
fixed speed regardless of the carrier line modulation speed (DCE)
of the PSTN modem connection. This eliminates the need to
have the DTE step up or step down in speed based on the
incoming or outgoing PSTN communication data rate.
Telephone Line Interface or DAA.
High performance modems are extremely sensitive to DAA (Data
Access Arrangement) performance. The difference between a
good modem and a fair one is in the DAA performance. The
iModem® family includes a unique low distortion DAA designed
for optimal performance over all PSTN line conditions thereby
achieving the most reliable and best performance PSTN connec-
tions.
The iModem® family is designed to meet North American
telephone standards as set by FCC Part 68 (USA) and CSA CS-
03 Part I (Canada). The PSTN line interface is UL1950 and CSA
C22-2 950 Listed (Third Edition) and is designed to meet 1500
VAC RMS isolation and provide 2122V peak surge protection.
Consequently, the iModem® family of products satisfies U.S. and
Canadian requirements, and will meet other international ap-
proval agency requirements that specify these levels of isolation.
Pins 1 and 2 function as both input and output connections to the
PSTN. To maximize field reliability in hostile environments, for
Canadian approval, for UL compliance, and also optionally for
FCC Part 15 compliance, these two pins must be routed through
an external network such as that described in Figure 6A and in
Cermetek Application Note #126.
Each iModem® product comes with FCC Part 68 approval and is
shipped from the factory with an FCC label indicating registration
number and ringer equivalent. This label should be prominently
displayed on the end product. With the exception of the U.S.,
most countries (including Canada) require submission of the final
product or system containing the iModem® to the appropriate
governing regulatory agency for approval.
The iModem® supports V.42 LAMP, MNP 2-4, MNP 10 error
correcting protocols and uses V.42bis data compression, allowing
data transmission rates of up to a maximum of 230.4kbps. These
high DTE data rates are supported by the iModem® serial inter-
face via its auto baud capability. Note that the maximum speed
attained is limited by the maximum speed available from the DTE
and not by the iModem®.
When the iModem® is operating in the internet state, all iNet AT®
Command communication between the iModem® and the host
processor (DTE) is conducted over the RS232 serial interface at
57.6kbps. When the iModem® is operating in the modem state,
communication with the DTE can be at any speed up to, and
including, 230.4kbps.
The resident Modulator/Demodulator supports line equalization and
forward error correction.
CONNECTING TO THE HOST UART
Since a modem 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.
SUPPORTED FEATURES
Standard AT Command Set.
The iModem® supports the standard Hayes AT Command set with
extensions and can operate with industry standard communication
software. The AT commands are compatible with TR302.2/88-
08006. Refer to Table 6A & 6B for the command set description.
iNet AT® Command Set.
Cermetek has created a set of iNet AT® command extensions for
control of the internet communication function. These commands
operate in the same fashion as the standard AT commands. Refer
to Table 6C for the iNet AT® command extension set.
Serial Host Interface.
The iModem® operates in asynchronous mode and supports both
the full RS-232C/V.24 serial interface and a 5V, RS232-like interface
called V.24 (EIA-232-E). Signal levels are TTL rather than RS-232V
level compatible, which allows direct connection of the iModem® to
the host’s UART without level translating circuitry. See Table 3 for a
complete set of pin descriptions.
The iModem® is controlled by sending serial commands over TXD
and by monitoring serial status messages returned on RXD. All
other serial interface lines may be utilized for the convenience of a
particular application but are not required by the iModem®. Unused
outputs from the iModem® should be left unconnected. Unused
inputs should be tied to the proper logic level. See Table 3.
When using the iModem® exclusively in an event driven application,
the serial interface is not required.
Speaker Interface.
The SPK output reflects the receiver analog input and provides a
signal test that can be used to monitor call progress. The SPK
signal can drive a 300 ohm load directly. Typically, the SPK signal is
input into an audio power amplifier and the amplifier, in turn, drives
the speaker coil. The speaker is activated with the ATLn command,
where n is 0, 1, 2, or 3.
Increasing numbers correspond to higher volume. Figure 3 indi-
cates one method of driving an external 8 ohm speaker.
The AT&Yn command selects one of the stored modem configu-
rations to be automatically recalled and made active upon reset
or power up. The ATZn command immediately recalls and
activates a stored configuration. See Tables 7A and 7B for
storable S-Registers and Commands. The NVRAM can save up
to four telephone numbers, with up to 36 digits or modifiers in
each telephone number. The AT&Zn=s command will store s, the
telephone number dial string. The ATDS=n command will cause
the modem to dial one of the four stored telephone numbers. The
NVRAM storage location for the four telephone numbers is
selected by an n of 0, 1, 2, or 3
Bell 103 CCITT V.22
Bell 212A CCITT V.22bis
CCITT V.32
CCITT V.32bis
CCITT V.34
CCITT V.34bis
CCITT V.90
The Modulation/Demodulation scheme supports the industry
modem standards listed below.

© 2000 Cermetek Microelectronics, Inc. Page 4 Document No. 607-0017 Rev. B (06/00)
Table 1. Data Formats Recognized by iModem® Family.
Table 2. iModem® Auto Configuration Based on DTE
Configuration.
Data Length No. of Character Length
Parity (No. of Bits) Stop Bits (No. of Bits)
None 7 2 10
Odd 7 1 10
Even 7 1 10
None 8 1 10
Odd 8 1 11*
Even 8 1 11*
*11 bit characters are sensed, but the parity bits are stripped off dur-
ing data transmission in Normal and Error Correction modes.
DTE Configuration iModem® Configuration
7 mark 7 none
7 space 8 none
8 mark 8 none
8 space 8 even.
Figure 4. Speaker Control Circuit.
Referring to Figure 5, use the variable resistor (POT) to set required
speaker volume.
To maintain FCC compliance, frequencies transmitted while in
voice mode should be between 300Hz and 3000Hz.
When voice and data are both being used, and the RXA and TXA
pins are active, it is typical for voice communication to precede data
communication. In this case, the following commands should be
used to configure the iModem® to allow for full utilization of the
Voice/Tone injection feature.
Voice/Tone Injection Port.
The iModem® Family provides pin T1 to allow the user to share the
PSTN line interface associated with the iModem® for voice and
DTMF applications. Figure 5 contains a schematic indicating one
possible configuration for voice/tone utilization.
All iModem® products are designed with pin T1 coupled directly to
the internal DAA. When using the iModem® in data mode, T1
should float and be disconnected from any potential signal because
any signal on T1 during data operation will affect the iModem®
output. If T1 is being asserted from another application, use a relay
or zero impedance switch to disconnect T1 when in data mode.
Automatic Speed/Format Sensing.
The iModem® supports both Command and Data modes of opera-
tion.
The iModem® can automatically determine the speed and format of
the data sent from the DTE over the serial interface; and can sense
the following broad range of speeds:
Figure 3. Zero Power Operation
The iModem® Family requires a single +5V +5% supply. It is
recommended that bypass capacitors be placed on the power
supply as close to the iModem® supply input pins as practical. It is
recommended that a 10 mF or greater tantalum capacitor in parallel
with a 0.1mF ceramic capacitor be used. The user must also
provide shielding from nearby sources of EMI, such as relays,
motors and other power supplies.
The iModem® is trained to a selected speed with an AT [CR] training
sequence. Thus, the DTE to modem serial interface speed can be
set independent of the DCE or line carrier connecting speed (with
minor restrictions, see the AT + MS command). This allows greater
flexibility when selecting DCE line carrier modulation speed thereby
affording the user with optimum data throughput performance. To
maximize effective modem data throughput speed, the DTE to mo-
dem serial interface speed should be set to the highest speed avail-
able without invoking the use of the iModem® built-in flow control.
Although flow control facilitates communication with higher speed
modes by the DTE, use of flow control causes an overall throughput
data rate penalty.
Power Supply.
The iModem® module is a complex set of sensitive sub-
systems. During the course of normal operation, the iModem®
decodes analog signals from the telephone line that are in
millivolt range. Steps must be taken by the user to guarantees
that power supply noise on all supply lines, including ground,
does not exceed 25 mV peak to peak. If necessary, use
dedicated power and ground planes. Failure to provide such
operating conditions could cause the iModem® to malfunction
or to function erratically.
The data formats in Table 1 are recognized by the iModem® family
of products.
The iModem® can sense data with mark or space parity and config-
ures itself as described in Table 2.
Referring to Figure 2, the controller activates the relay switch,
supplying power (+5V) to the iModem®. In this configuration, the
ring signal is used to “wake up” the iModem® when the iModem® is
in the power down state.
The pins of the iModem® will be in an undefined state when power
is switched off. This must be taken into consideration to assure that
no unwanted signals are presented to the iModem® during power
down.
Zero Power Mode.
If an application calls for zero power during standby periods, the
power may be switched off using external circuitry and then
reapplied when the iModem®’s RI pin becomes active. The
iModem® can thus be powered down to zero.
300, 600, 1200, 2400, 4800, 7200, 9600, 12000, 14400, 16800,
19200, 21600, 24000, 26400, 28800, 38400, 57600, 115200 and
230400bps.

© 2000 Cermetek Microelectronics, Inc. Page 5 Document No. 607-0017 Rev. B (06/00)
Figure 5. iModem® Family Application Diagram
The iModem® 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 HS Modem can be put into data
mode by issuing the command ATO [CR].
THE COMMAND FORMAT
Typical commands consist of three elements:
1. The attention sequence,
2. The commands themselves and
3. A terminating carriage return.
WARNING: the iModem® 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.
AT [commands] [CR].
Where: [AT] represents attention sequence.
[commands] represents command strings.
[CR] represents carriage return (ASCII 13 or HEX 0D).
When entering commands to the modem, the backspace charac-
ter-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 in the command line. A command line may be as long
as 40 characters, excluding the letters AT.
These commands disable auto-answer and eliminate hang-up due
to lack of carrier signal.
1. Enter: ATS0=0 [CR]
2. Enter: ATS7=255 [CR]
3. Enter: ATS10=255 [CR]
2. To switch to data mode, switch local voice source from
RXA and TXA:
(a) At the Originate Modem, enter: ATX1 [CR]
(b) At the Answer modem, enter: ATA [CR]
3. To disconnect (hang-up) a voice call or data call:
(a) Return to control mode by Entering: +++
(b) Enter: ATH [CR]
4. To place a voice call using the HS Modem DTMF facili
ties:
(a) Enter: ATDT(Tele)#;[CR]
(b) Then switch to local voice source
iModem® STATES
The iModem can be in either the Internet State or the Modem
State. Because the iModem® has the unique ability to
operate as either a high speed V.90 Modem or as an internet
email transceiver, the commands sent on TXD (or the status of
the Send Email Control Pin) determine operation.
iModem® Internet State.
The iModem® can be controlled by providing status flags on the
Send Email Control Pin (pin #6) or by sending ASCII commands via
the serial interface. Use of Pin #6 forces Internet email transmis-
sion operation. Upon successful transmission of an EMAIL, the
iModem® sends a momentary 100ms Low going TTL output pulse
on the Email Accepted Pin (Pin #8) indicating the email has been
received by the ISP Mail Server. If desired, a simple latch circuit
(see example in Figure 8) can be used to illuminate an LED to indi-
cate Email Accepted.
Thefollowingcommand sequences illustrate implementation of com-
mon voice/tone port applications.
1. To answer a voice call:
(a) Enter: ATH1 [CR]
(b) Switch local voice source into RXA and TXA
(c) Begin voice conversation. The escape sequence consists of a “guard time” (a period where no
characters are sent to the modem), followed by 3 escape charac-
ters, followed by another guard time. At power-up, the guard time is
set to 1 second minimum, and the escape character is set as “+”.
These two parameters can be modified via registers S2 and S12,
respectively.
iModem® Modem State.
When in the Modem State, the iModem® 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 trans-
mission is in progress, the iModem® is in the data mode state and
will not recognize commands. To force the iModem® to recognize
commands, the host must send an “escape sequence” to the
iModem® forcing it out of data mode and into command mode.
This message indicates command completion status. Refer to
Tables 5A, 5B and 5C for a complete list of status messages.
®

© 2000 Cermetek Microelectronics, Inc. Page 6 Document No. 607-0017 Rev. B (06/00)
iModem® Training Command Sequence.
The iModem® is trained by sending it the following sequence:
Enter: AT[CR]
Where: A and T may be either upper or lower case but
must be the same case.
[CR] represents carriage return.
iModem® will respond with one of the following status messages,
depending on whether it is optioned for abbreviated or English
status messages.
Result: 0[CR] (Abbreviated form)
Result: [CR][LF][OK][CR][LF] (English form)
Where: [CR] represents carriage return (ASCII 13 or
HEX 0D)
[LF] represents line feed (ASCII 10 or HEX 0A)
The iModem® is now in idle, the DTE speed is set to a default
speed of 57.6kbs mode and the iModem® is ready to accept
commands.
As 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, it must be in the upper case ASCII. No
carriage return is needed.
Extensions to the basic result code set can be specified by Register
S95, which allows for the use of result codes 40 - 64, 165 - 194.
Note: To obtain a detailed status report for a given modem commu-
nication configuration, use the AT/V1 command. Executing this
command at setup will cause the iModem® to connect and return a
message on line consisting of <DTE speed> <modulation> <error
protocol> <line speed of connection>.
AT COMMAND APPLICATIONS WHEN OPERATING THE
iModem® IN THE INTERNET STATE
Each iModem® is delivered with a pre-programmed ISP account ID
and password, local Sunnyvale, CA, dial-up ISP access phone
number and a default pre-programmed email subject title for use
on an interim basis.
Sending Emails.
If an email is to be sent utilizing the Cermetek pre-programmed
internet configuration profile (i.e., the pre-programmed ISP account
ID and password, and the pre-programmed destination email
address), issuing the @TD command is all that is needed to send
an email.
Example: Initiate dial-up and complete email
transmission using the pre-programmed
internet configuration profile.
Enter: @TD
The user may suppress certain subsets of the non-extended
result codes. This is accomplished by selecting subsets of the
result code set using the ATXn command, where n=0, 1, 2, 3.
Optionally, the user may specify an extended set of result codes
(codes above 35) by setting Register S95. See the detailed
description of result codes in Table 5A, Table 5B and Table 5C.
All AT commands, other than dialing commands, will be re-
sponded to with either an OK (short form result code 0) if the
command is valid or accepted, or with an ERROR (result code 4)
if the command is not recognized. The detail contained in the
error result code signaled to the DTE depends on the level of
message suppression employed by the user. As can be seen
from Tables 5A, 5B and 5C, specifying X4 allows the iModem® to
utilize the entire range of non-extended messages, whereas X0
suppresses all but the very basic result codes. Most of the result
codes allowed under X1, X2 and X3 are considered call progress
status codes and, in practice, are suppressed except for the case
of debugging activities. It is recommended that the non-extended
result codes be used in all cases.
It should be noted that the default connect result codes 9-20
indicate DTE connection speed, not Carrier Line DCE speed.
Hence, the iModem® will connect at a maximum speed of
57.6kbps (result code 18) unless the DTE is forced to a higher
speed by selection of data compression. In this case, the
maximum DTE to iModem® speed is 230.4kbps (result code 20).
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 line feed).
INITIALIZING THE iModem®
Before commands may be sent to the iModem®, the iModem®
must be initialized. This consists of two events:
1. Modem Reset. This is accomplished by applying a hardware
reset pulse to pin RST or by switching the power off and then
back on.
2. Initial Modem Training. The modem must be trained to the
host DTE speed and parity (odd, even, mark, space or none).
These activities are briefly described below.
Reset.
Upon applying power to the iModem®, the iModem® automati-
cally generates an internal reset pulse. The user can 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 been
stabilized. Delay sending commands to iModem® for 900ms after
reset has been initiated to allow the iModem® time to properly
reconfigure.
On power up, or when reset is initiated either by command ATZ or
by the RST pin, the iModem® will reconfigure to it’s default state
with the line carrier modulation DCE speed set to 56 kbps.
If desired, any speed, error correction, or data compression
method available on the iModem® can be locked in, using the
AT\Nn and/or AT+MS commands.
Training the iModem®.
The iModem® must be trained to match the host DTE speed and
parity so that it is able to recognize serial asynchronous com-
mands sent to it by the DTE.
The DTE must retrain the iModem® each time a reset pulse is
applied on RST or after a RESET serial command has been
issued.
By way of example, the command below instructs the iModem® to
configure itself to not echo characters when in command mode
(E0) and then put itself in answer mode (A).
Enter: ATE0A[CR]
Standard AT Command Set.
The Hayes AT command set is divided into four types of com-
mands: dial modifiers, basic commands, ampersand and percent
commands. Refer to the complete list in Tables 6A and 6B.
STATUS MESSAGES AND RESULT CODES
A result code is issued by the iModem® to the DTE for all
commands executed by the iModem®, except dialing and internet
commands. Further, various activities on the PSTN are also
signaled to the DTE by the iModem®.

© 2000 Cermetek Microelectronics, Inc. Page 7 Document No. 607-0017 Rev. B (06/00)
AT COMMAND APPLICATIONS WHEN OPERATING THE
iModem® IN THE MODEM STATE.
In the last example, the entire pre-programmed internet configu-
ration profile is over ridden.
Dialing A Phone Number.
The Dial command takes the form Dn, where n is a string of
characters. In the simplest form, n will be only the digits of the
phone number to be dialed.
Example: Dial Number.
Enter: AT D1234567
In response to this command, the iModem® 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 iModem® automatically releases the line
and sends a NO CARRIER result code.
The default email subject title is:
Cermetek Microelectronics iModem Email
Further, Input #1 and Input #2 status will also be transmitted. For
CH2156, CH2158/9 and CH2160, the default send email will be of
the form:
Remote Product Message
Input 1 High (or low)
Input 2 High (or low)
For CH2157, which contains an onboard temperature sensor, the
default send email is of the form:
Remote Product Message
Temperature xx (Reported in Fahrenheit)
Input High (or low)
To change the default internet configuration profile, refer to the
PROGRAMMING THE iMODEM® section of this data sheet.
Fully Autonomous Control.
If email is to be sent by activating the SEND EMAIL CONTROL
PIN (PIN#6), the iModem® will utilize the pre-programmed internet
configuration profile.
The iModem® is designed to allow the user to personalize the
default internet configuration profile by either using the PSTN to
dial up the iModem® or by using the RS232 host serial interface.
Once reconfigured, simply activating the SEND EMAIL CONTROL
PIN will automatically cause an email to be transmitted.
In a typical fully autonomous application, the user installs “as
received” the iModem® in the desired remote environment and
connects only the incoming PSTN to the systems jack.
Once the PSTN is connected, the user accesses the iModem®
and then re-configures the iModem® in situ. Upon completion of
the re-configuration activity, the iModem® can now be directed to
send emails from the remote environment by activating the SEND
EMAIL CONTROL pin.
Semi-Autonomous and Complete Host Intervention Control.
This method of control requires all commands to be issued in
serial fashion. The first example assumes that the pre-pro-
grammed ISP and email address is to be used.
A common host control application involves using the iModem®
pre-programmed internet configuration profile except for the local
access ISP phone number.
Example: Initiate dialup using a local ISP access
phone number different from the pre-
programmed number. Then complete
email transmission using the pre-
programmed ISP account, ID password
and email destination address.
Enter: @TN1234567 New Phone Number
Enter: @TD Initiate dialup and send email
In a slightly more complex example, the host controller over rides
both the ISP access phone number and the destination email
address. The email is then sent using the @TD command.
Example: Send email Overriding the pre-
programmed ISP local access phone
number and default pre-programmed
destination email address. For all other
parameters, use pre-programmed
information internet configuration
profile.
Enter: @TSeeeeee Where eeeeeee is
the email subject
(limited to 15 ASCII
characters)
Enter: @TD Dial up ISP and
complete email
transmission using
above data for email
accounts.
iNet AT® commands must be sent from the Host controller at
57600bps, N81 (no parity, 8 databits, 1 stop bit).
Note that the ISP Mail Server Address must be specified in
Hexadecimal. Refer to Cermetek Application Note #147, “Proce-
dure to convert user account address to Hexadecimal”.
Example: Over ride default pre-programmed ISP
account ID & Password, email destina
tion address, local access phone
number, send email.
Enter: @TLaaaaaa Where aaaaaa is ISP
account ID
Enter: @TPbbbbbb Where bbbbbb is ISP
account Password
Enter: @TOcccc Where cccc is ISP
mail server address
Enter: @TNdddddd Where dddddd is the
local ISP access
phone number
Enter: @TNaaaaaaa Where aaaaaaa is
the ISP local access
phone number
Enter: @TObbbbbb Where bbbbbb is the
email destination
address
Enter: @TD Dial-up ISP and send
email.
Changing the Default Internet Configuration Profile.
When various iNet AT® commands that modify internet configura-
tion parameters are issued to the iModem®, the changes invoked
by these commands are only temporary. Once power to the
iModem® is removed, the changes are lost. The default configu-
ration profile will not be lost when power is removed from the
iModem®.

© 2000 Cermetek Microelectronics, Inc. Page 8 Document No. 607-0017 Rev. B (06/00)
Table 3. iModem® Family Pin Descriptions

© 2000 Cermetek Microelectronics, Inc. Page 9 Document No. 607-0017 Rev. B (06/00)
Table 4. Pin Comparison of CH179X, HS Modem and CH21XX
iModem® Family
Example: Dial 9, pause, dial number.
Enter: ATDT9, T1234567
Multiple commas may be used for a greater delay time.
Touch Tone and Pause Dialing
The iModem® can use DTMF (touch-tones) “T”, or dial pulses “P”
when dialing a telephone number. If the dial command does not
specify which type to use, the modem defaults to the type last
specified. The power-on default value is T.
Example: Pulse dial 9, pause, touch-tone dial
number
Enter: ATDP9, T1234567
Redial Last Number.
Use A/, the repeat command, to redial the last telephone number
dialed when a busy signal is received.
Example: Touch-tone dial 9, pause, dial number,
return for command.
Enter: ATDP9, T1234567;
Return to Command State.
The iModem® can be forced to reenter the command state after
dialing (without hanging up) by ending the dial command with a
semi-colon. This is useful when using the modem as an auto
dialer.
Automatic Answering.
S0=0* DO NOT ANSWER TELEPHONE
S0=1-254 ANSWER ON RING 1 TO RING 254
S0=255 ANSWER ON RING 255
*When S0 is set to 0, the modem will not auto answer.
PROGRAMING THE iModem®
Cemetek’s iModem® requires an ISP (Internet Service Provider)
address, ISP account password, local PSTN dial up phone
number and valid email address to send and receive emails.
The required information can be modified by including it on the
appropriate iNet AT® Command line at the time the commands
are issued from the host processor.
Commands can be issued to the iModem® using any number of
commercially available terminal emulation programs - such as
PROCOM or HYPER TERMINAL. As an added service to our
customers, each iModem® is shipped from the factory with a
default ISP account and password for interim use. The default
PSTN dial up phone # is local to Sunnyvale, CA.
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 commands the iModem® to pause for a specific length
of time. The factory default pause time is 2 seconds.
If a carrier is detected, the iModem® gives a CONNECT result
code and goes on-line, permitting communication with the distant
modem.
The Dial Command may also be issued without a telephone
number. ATD causes the iModem® to pick up the telephone line
without dialing a number.
NIP medoMi XX12HC YLIMAF medoMSHdnaX971HC YLIMAF
1GNIRGNIR
2PITPT
3IT1T
4CNTNES
5KPSKPS
6CNDNES
7CN1NI
8*NEPO2NI
9CNCN
01DXTDXT
11DXRDXR
21CNCN
31RTDRTD
41RSDRSD
51IRIR
61STCSTC
71DCDDCD
81CNCN
91V
cc
V
cc
02DNGDNG
12TSRTSR
22STRSTR

© 2000 Cermetek Microelectronics, Inc. Page 10 Document No. 607-0017 Rev. B (06/00)
Table 5A Summary of Non-Extended Result Codes. Table 5B Extended Result Codes.
Note: 1. Am “x” in a column indicates that the message (either the long form if verbose, or the value only for short form) will be generated
when that particular value of “n” (shown at the top of the column) has been selected by the use of ATXn. A numeral indicates which less
explicit message (verbose or short form) will be output for that X option.
Table 5C. Extended Result Codes. Table 5C. Extended Result Codes.
esreT ro trohS
roesobreV gnoL 01234
56100023TCENNOCXXXXX
66100043TCENNOCXXXXX
76100063TCENNOCXXXXX
86100083TCENNOCXXXXX
96100004TCENNOCXXXXX
07100024TCENNOCXXXXX
17100044TCENNOCXXXXX
27100064TCENNOCXXXXX
37100084TCENNOCXXXXX
47100005TCENNOCXXXXX
57100025TCENNOCXXXXX
67100045TCENNOCXXXXX
77100065TCENNOCXXXXX
87100065TCENNOCXXXXX
971004032TCENNOCXXXXX
esreT ro trohS
roesobreV gnoL 01234
08100082TCENNOCXXXXX
18133392TCENNOC1XXXX
28176603TCENNOC1XXXX
38133333TCENNOC1XXXX
48176643TCENNOC1XXXX
58133373TCENNOC1XXXX
68176683TCENNOCXXXXX
78133314TCENNOCXXXXX
88176624TCENNOCXXXXX
98133354TCENNOCXXXXX
09176664TCENNOCXXXXX
19133394TCENNOCXXXXX
29177605TCENNOCXXXXX
39133335TCENNOCXXXXX
49177645TCENNOCXXXXX
Result Code Form n in ATXn Command Result Code Form n in ATXn Command