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V.23 Data Pump Software for Texas TMS320C54x/C55x & C2xx/C5x DSPs

This software implements the ITU Data Modem function V.23, which provides half-duplex data transmission at two maximum rates, one of up to 1200b/s and the other of up to 600b/s, over the telephone network. Also provided (optionally) is a half-duplex backward channel of 75b/s which can be operated independently of the main channel. Duplex channel separation is achieved by band splitting. The software is in the form of two callable subroutines, one for initialisation and one for per-sample processing of input/output samples and data bits. The user is responsible for interfacing sample and data input & output to hardware. Blocks of data and samples can be processed by making multiple sub-routine calls. The ‘C54xC55x code version is re-entrant to facilitate the implementation of multiple modems on a single DSP. A comprehensive user's guide is provided with the code. Test results are available.

Interfaces: at the sample interface, the code can operate at 9.6kHz or 8.0kHz sample rates. At the data interface, operation can either be in Asynchronous or in Synchronous mode. In Asynchronous mode, data is transferred in bit-blocks on a per-character basis; start & stop bits are auto-inserted/detected. In Synchronous mode, data is transferred on a per-bit basis. Clock recovery on bit transitions is provided in the receiver. In both cases, the nominal clock used is selected as 1200Hz or 600Hz. At the control interface, one 16-bit control word sequences operations and sets parameters, and one diagnostic word conveys data transfer status.

Performance:

• SNR for 10^-6 error rate at 1.2kb/s is: 12.5dB - Flat Channel

DSP Load - C54x/C55x version - #denotes with backward channel:

• MIPS: 2.7(6.9#) - 8.0kHz s.r. - or 3.3(6.2#) - 9.6kHz s.r.

• Data memory: 53(133# - 8.0kHz s.r. - or 98# - 9.6kHz s.r.) words

• Program memory: 0.5k(1.2k# - 8.0kHz s.r. - or 0.9k# - 9.6kHz s.r.) words

DSP Load - C2xx/C5x version: operation at an 8.0kHz sample rate requires an extra 0.7MIPs, 30 data memory and 0.3k program memory words:

• MIPS: 3.3(6.1#)

• Data memory: 61(116#) words

• Program memory: 0.6k(1.0k#) words

Availability: NOW - sale is under licence - integration support offered