SI2414 SILABS [Silicon Laboratories], SI2414 Datasheet - Page 18

• Manufacturer Part Number: SI2414
• Manufacturer: SILABS [Silicon Laboratories]

Si2456/Si2433/Si2414
Functional Description
The
embedded modem chipset with integrated direct access
arrangement (DAA) that provides a programmable line
interface to meet global telephone line requirements.
Available in two small packages, this solution includes a
DSP data pump, a modem controller, on-chip RAM and
ROM, an analog front end (AFE), a DAA, and an analog
output.
The
commands and provides connect rates up to 56/33.6/
14.4 kbps full-duplex over the Public Switched Telephone
Network (PSTN). The Si2456/33/14 features a complete
set of modem protocols, including all ITU-T standard
formats up to 56 kbps.
The ISOmodem provides numerous additional features
for embedded modem applications. The modem includes
full caller ID detection and decoding for global standards.
Call progress is supported through echoing result codes
and is also programmable to meet global settings.
Because the Si2456/33/14 ISOmodem integrates the
DAA, analog features, such as parallel phone detect,
overcurrent detection, and global PTT compliance with a
single design, are included.
This device is ideal for embedded modem applications
due to its small board space, low power consumption,
and global compliance. The Si2456/33/14 solution
includes a silicon DAA using Silicon Laboratories’
proprietary ISOcap™ technology. This highly-integrated
DAA can be programmed to meet worldwide PTT
specifications for ac termination, dc termination, ringer
impedance, and ringer threshold. In addition, the Si2456/
33/14 has been designed to meet the most stringent
worldwide requirements for out-of-band energy, billing-
tone immunity, lightning surges, and safety requirements.
The Si2456/33/14 is designed to be rapidly incorporated
into existing modem applications. The device interfaces
directly through either a serial UART to a microcontroller
or through a standard RS-232 transceiver. This interface
allows for PC evaluation of the modem immediately upon
powerup via the AT commands using standard terminal
software. The Si2456/33/14 also provides an 8-bit
parallel port.
The Si2456/33/14 solution requires only a few low-cost
discrete components to achieve global compliance. See
the "Typical Application Circuit" on page 11. Table 8 on
page 15 outlines the functional modes of the Si2456/33/
14 modem. For additional information, see the Si2456/
33/14 Programmer’s Guide.
18
Si2456/33/14
Si2456/33/14
accepts
ISOmodem™
standard
is
a
modem
complete
AT
Rev. 0.9
Digital Interface
The Si2456/33/14 digital I/O can be configured as either
a serial UART interface with flow control or as a parallel
8-bit interface.
Selection of a serial or parallel I/O interface is
determined by the state of AOUT/INT (Si2456/33/14,
pin 13) during the rising edge of RESET. An internal
pullup resistor forces the default state to serial mode
operation. An external 10 kΩ pulldown resistor can be
connected to AOUT/INT to force selection of parallel
mode. Additionally, when selecting parallel mode, CS
should remain high until after the rising edge of RESET.
Configuration of pins 3, 4, 8–11, 13–16, and 22–24 is
determined by this interface selection.
Serial Interface
This section describes the basic operation of the
Si2456/33/14 serial UART interface. The Si2456/33/14
supports DTE rates up to 307.2 kbps with the standard
serial UART format. Upon powerup, the UART defaults
to a 19.2 kbps baud rate. If a pulldown resistor ≤ 10 kΩ
is placed between D2 (Si2456/33/14, pin 16) and GND
(Si2456/33/14, pin 6), the DTE rate is 2400 bps 8N1
after reset. This rate may be changed through the
extended AT\Tn commands listed in Table 14 on
page 30. Immediately after the AT\Tn command is sent,
the host must program its UART to the new baud rate.
The UART interface synchronizes on the start bits of
incoming characters and samples the data bit field and
stop bits. The interface is designed to accommodate
character lengths of 8, 9, 10, and 11 bits giving data
fields of 6, 7, 8, or 9 bits. The Si2456/33/14 defaults to a
character length of 8 (8N1), and the character length
can be set via the \Bn command. Under some \Bn
options, parity may be set using the \Pn command.
The serial interface provides a hardware pin, DCD (data
carrier detect), which remains low as long as the
ISOmodem is connected. This and other signals can
also be monitored via the I/O Control 0 register (U70).
The INT interrupt pin can be programmed to alert the
host of changes in DCD and the other interrupts listed in
I/O Control 0 (U70). After an interrupt has been received
by the host via the INT pin, the host should issue the
AT:I command. This command causes a read-clear of
the CID, OCD, PPD, and RI bits of the U70 register and
raises (deactivates) the INT pin.