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Caller ID Generator (Japan) TMS320C5000 DSP Code

Description: implements Caller IDentity - CID - generation for communicating call data on-hook over telephone lines to subscribers as implemented in Japan. Here before the 1st normal ring, the exchange sends a line reversal followed by a set of short rings that should be inaudible in a normal subscriber phone. The phone responds by going off-hook, triggering the exchange to send the CID message data. After reception, the phone reverts to on-hook, and the exchange continues with normal ringing.
         The CID message is a pre-amble of mark carrier followed by the message byte data and finally a cyclic redundancy check (CRC) byte-pair, all modulated as a V.23 modem signal. The byte data consists of multiple parameter groups. The CID Generator - Encoder+Transmitter - implements the message data communication for the exchange end. The software function summary is:

CID Encoder - sequences the pre-amble of mark carrier signal for a user-set period, followed by the fixed start 5 bytes, then bytes from the message data buffer adding parity, then the fixed end 2 bytes, and finally the formed CRC byte-pair

The Encoder generates line signal samples using the following routine, available on its own:

CID Transmitter (as used with "standard" CID) - accepts pre-amble or message data bytes adding start/stop bits then, with per-sample timing for 1200b/s, frequency-modulates at V.23 (1300Hz Mark, 2100Hz Space) to generate each transmit sample

The Generator requires a buffer of the complete message data to be pre-loaded at the user interface in parameterised byte form, excluding the CRC bytes. Message parameterisation in the user code gives flexibility in dealing with Caller ID categories. The message buffer format is 2 per 16-bit word for efficiency in multi-channel use.
Each function has an initialisation routine and a per-sample main routine and is re-entrant with memory offset-addressing for multi-channel operation. As well as from assembler, the routines can also be called from C, wrappers being provided. The C main routines enable multiple sample blocks to be processed. Sample rates of 8.0kHz or 9.6kHz can be set. A comprehensive user's guide is provided with the code.

Processor Load:

Function MIPS# Data memory (words) Prog memory (words)#
CID-J Generator (Encoder+Transmitter) 0.40 4 + (6 + M) x N 223
CID Transmitter only 0.26 4 + 4 x N 64

- #figures are for TMS320C54x operation with the assembler interface at 8.0kHz sampling
- in data memory figures M is the user-set buffer size at 2 bytes per word and N is no. of channels

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

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