CH1794A Cermetek Microelectronics, CH1794A Datasheet - Page 5

• Manufacturer Part Number: CH1794A
• Manufacturer: Cermetek Microelectronics

Specifications of CH1794A

• Lead Free Status / RoHS Status: Not Compliant

Cermetek Microelectronics, Inc.
The HS Modem 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
modem serial interface speed should be set to the
highest speed available without invoking the use of the
HS Modem’s built-in flow control.
control facilitates communication with higher speed
modes by the DTE, use of flow control causes an
overall throughput data rate penalty.
Table 1. Data Formats Recognized by HS Modem
Family.
Voice/Tone Injection Port. The HS Modem Family
provides pin T1 to allow the user to share the PSTN
line interface associated with the modem for voice and
DTMF applications.
which uses a 5 Volt single supply operational amplifier
and indicates one possible configuration for voice/tone
utilization.
Refer to Cermetek Application Note #170, 2-4 Wire
Converter for Use with CH179X and CH2056 Modems,
for an alternative voice/tone implementation that
utilizes dual supply operational amplifiers.
Table 2. HS Modem Auto Configuration Based on
DTE Configuration.
All HS Modem products are designed with pin T1
coupled directly to the internal DAA. When using the
HS Modem in data mode, T1 should float and be
disconnected from any potential signal because any
signal on T1 during data operation will affect the HS
Modem’s output. If T1 is being asserted from another
2007 Cermetek Microelectronics, Inc.
*11 bit characters are sensed, but the parity bits are
stripped off during data transmission in Normal and
Error Correction modes.
Parity
None
None
Even
Even
Odd
Odd
DTE Configuration
7 space
8 space
7 mark
8 mark
Data Length
(No. of Bits)
7
7
7
8
8
8
Figure 5 contains a schematic
No. of
Stop
Bits
2
1
1
1
1
1
Configuration
HS Modem
7 none
8 none
8 none
8 even
(No. of Bits)
Although flow
Character
Length
11*
11*
10
10
10
10
Page 5
application, use a relay or zero impedance switch to
disconnect T1 when in data mode.
When voice and data are both being used, and the T1
pin is active, it is typical for voice communication to
precede data communication.
following commands should be used to configure the
HS Modem to allow for full utilization of the Voice/Tone
injection feature.
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>
Figure 3. Speaker Control Circuit.
The
implementation
applications.
1. To answer a voice call:
2. To switch to data mode, switch local voice source
3. To disconnect (hang-up) a voice call or data call:
4. To place a voice call using the HS Modem DTMF
Modem-on-Hold (MOH). The Modem-on-Hold (MOH)
feature enables the CH2056A modem to temporarily
pause a data call to the Internet by placing the call on
hold to allow usage of the same PSTN line to accept
an incoming call or to initiate an outgoing voice call.
(a) Enter: ATH1<CR>
(b) Switch local voice source into T1
(c) Begin Voice Conversation
from T1:
(a) At the Originate Modem, enter: ATX1<CR>
(b) At the Answer Modem, enter: ATA<CR>
(a) Return to control mode by entering: +++
(b) Enter: ATH<CR>
facilities:
(a) Enter: ATDT1234567<CR>
(b) Then switch to local voice source
CH179XA/2056A High Speed Family of Ultra Small Modems
following
Where 1234567 is the phone number
command
of
Document No. 607-0020 Revision B (01/07)
These commands disable auto-
common
sequences
In this case, the
voice/tone
illustrate
port