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DTMF Transmitter TMS320C5000 DSP Code

Description: generates digit signals to standard Dual Tone Multi-Frequency (DTMF) telephone format. With DTMF, the 16 possible digits are each signified by pairs of tones, one from a "low" group - 697Hz, 770Hz, 852Hz, 941Hz - and the other from a "high" group - 1209Hz, 1336Hz, 1477Hz, 1633Hz.
         To suit applications, the following parameters are made user-programmable: low- and high-tone transmit powers, digit-on timing, digit-off timing. For test purposes, continuous transmission can be set. Sample rates of 8.0kHz or 9.6kHz can be operated.
         The software is in the form of four callable subroutines: one sets common-channel default parameters, one initialises per-channel memory, one is for loading each new digit into each digit queue, and one is for per-sample generation. The user is responsible for supplying the codes of digits to be dialled and for accepting each transmit sample. Digits to be dialled can be placed in a queue whose maximum length is programmable.
         In the assembler interface, the software can be operated in a multi-channel mode: a pointer is set to each per-channel block of memory at each sub-routine call. By making multiple sub-routine calls, the code can also generate blocks of samples. A C-callable wrapper can also be provided, wherein individual channels can be called from C to generate multiple sample blocks. A user's guide is supplied.

Specification: The values PL, PH and Ton, Toff are user-programmable.

Processor Load:

- #figures are for TMS320C54x operation with the assembler interface at 8.0kHz sampling
- *for 16-digit queue

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