DS_2901CE_031
73M2901CE Data Sheet
5 Firmware Description
An “AT” command interpreter provides command and configuration of the 73M2901CE. This provides the
user a uniform interface to control the modem in embedded applications. The signal processing is
performed to provide data to the DAC and process data from the A/D converter. A MAC hardware
coprocessor is provided for computation.
To provide maximum flexibility, the system host processor can access the internal RAM and Control
Register space in the modem. This will allow the OEM user to modify parameters such as filter response
and transmit levels through the AT command set using proprietary commands. The host processor can
also access the modem I/O port pins, providing extended I/O capability.
Refer to the
73M2901CE AT Command User Guide
for a complete description of the software.
5.1
Firmware Overview
The modem always powers up in the idle (on hook) mode. “AT” commands are issued via the serial
interface from the host. All modem configuration commands are received in this manner. The data
modem firmware is contained in an internal ROM.
The firmware will automatically enter a power saving idle mode if the modem is on hook and there are no
incoming host commands. The modem automatically powers up upon receiving the next command. This
power up sequence occurs without delay to the host. This function, while saving power, is transparent to
the host processor and can be disabled by the host via an “AT” command. The host can also program
the modem to power down via an external pin (DTR) or via a firmware command.
5.2
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Firmware Features
“AT” command set
Supports data standards through V.22bis
Provides DAA control firmware (e.g. ring detect, hook control)
Multinational Call Progress support (FCC part 68, ITU CTR21, Japan JATE, etc.)
Caller ID capability
FSK demodulation (V.23, V.21, Bell 202 and Bell 103)
DTMF detection and decoding
Selectable number of rings and line reversal for CID data operation
On hook CID data operation
On hook Line-In-Use detection support (No line seizure will occur when a Line-In-Use condition is
detected)
Off hook Parallel Pick-Up detection support (Line seizure will be aborted as soon as a Parallel Pick-Up
condition is detected)
Off hook voltage change detection (requires external circuitry)
Receive energy change detection
Directly interfaces with standard V.24/EIA-232 bus drivers (3.3 V inverted level) serial interface using
the built in serial port and firmware control of port pins
Provides tone generation and detection including four imprecise and four precise call progress detect
filters with programmable frequency and detection threshold
Blacklisting capability
Long Space disconnect support
Inactivity timeout
Host access to program RAM provided
User programmable general purpose I/O
Rev. 3.3
13
TERIDIAN [ TERIDIAN SEMICONDUCTOR CORPORATION ]
