RC56D, RC336D, and RC144D Modem Device Sets Designer’s Guide
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Conexant
1-7
Host-Based DSVD
All modem models support host-based ITU-T V.70 DSVD. The RCDSVD SCP (R6715) is not required. V.70 software drivers
for Windows 95 are provided which support a speech/audio bit rate of significantly less than 8.0 kbps by implementing
interoperable G.729 and G.729 Annex A with interoperable G.729 Annex B. The minimum PC performance recommended for
host-based DSVD is 150 MHz Pentium or equivalent. The V.70 software drivers require about 10% of the MIPS available in a
Pentium 150 MHz class PC. The host PC must supply full-duplex sound support, typically to a microphone/speaker, such as
provided by Conexant WaveArtist devices or a sound card. The modem is configured for host-based V.70 via AT commands,
and, when using a TAPI-compliant communication application, the V.70 software drivers will automatically run upon a
successful V.70 connection.
Sleep Mode
Sleep Mode is supported in the modem device set and the RCDSVD SCP device.
1.3.2 Devices
Modem Data Pump (MDP)
The data/fax/voice/optional speakerphone modem data pump (MDP) is a Conexant R6764 packaged in a 100-pin PQFP. The
input clock frequency is 28.224 MHz and can be supplied by the MCU. An internal phase locked loop (PLL) circuit supports
56.448 MHz internal operation. The operating voltage is +3.3V, which can be supplied by the MCU, with +5V tolerant inputs.
The MDP su5V analog signal interface.
In V.90/K56flex data modem mode (RC56), the MDP can receive data from a digital source using a V.90- or K56flex-
compatible central site modem at line speeds up to 56 kbps. Asymmetrical data transmission supports sending data at
speeds up to V.34 rates.
In V.34 data modem mode, the MDP can operate in 2-wire, full-duplex, synchronous/asynchronous modes at line rates up to
33.6 kbps. Using V.34 modulation to optimize modem configuration for line conditions, the MDP can connect at the highest
data rate that the channel can support from 33.6 kbps to 300 bps with automatic fallback. Automode operation in V.34 is
provided in accordance with PN3320 and in V.32 bis in accordance with PN2330.
In fax modem mode, the MDP supports Group 3 facsimile send and receive speeds of speeds of 33600, 31200, 28800,
26400, 24000, 21600, 19200, 16800, 14400, 12000, 9600, 7200, 4800, and 2400 bps.
ADPCM voice processing is supported.
Downloading of MDP code from the MCU is supported.
Microcontroller (MCU)
The MCU is a Conexant 8-bit microcomputer with pins to support host/ DTE, MDP, voice/audio/speakerphone, and optional
RCDSVD SCP interface operation. The operating voltage is +5V. The MCU provides a +3.3V output to power the MDP.
The MCU connects to the host via a V.24 (EIA/TIA-232-E) serial interface or a parallel microcomputer bus depending on
installed MCU firmware.
The MCU performs the command processing and host interface functions. The crystal frequency is 28.224 MHz. The MCU
outputs a 28.224 MHz clock to the MDP eliminating need for a separate MDP crystal circuit.
The MCU connects to the MDP via dedicated lines and the external bus. The external bus also connects to OEM-supplied
RAM and ROM/flash ROM, and to the optional RCDSVD SCP.
The MCU connects to an optional 256-byte serial EEPROM over a dedicated serial interface.
The MCU is packaged in an 80-pin PQFP.
RCDSVD Speech Codec Processor (SCP) (Optional)
The RCDSVD SCP (R6715-14), required for on-board DSVD operation, is packaged in a 100-pin PQFP. The 56.448 MHz
crystal frequency is supplied by the MDP XCLK output.
Summary of Contents for RC144D
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