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ELC 152, 1st Semester, 2004-2005
Lab Exercise 4

DTMF Tone Generation on the 'C542

This exercise requires use of the 'C542 kits, the dskplasm assembler, and the associated C54x Code Explorer software in the DSP Lab.

Read the project documentation of Dominguez and Zuloaga on Dual Tone Multifrequency Generation Using Visual C++ (ELC152-oct2003-07) for information and references regarding standards for DTMF tones in telecommunication systems. Other references on DTMF tones will also do.

Your goal is to write code to generate a repeating sequence of DTMF tones on the 'C542. You are to generate the sequence corresponding to #d₁d₂d₃d₄d₅d₆* , where d₁d₂d₃d₄d₅d₆ is your 6-digit ID number. Operate the analog interface at 8000 Hz.

Each of the eight DTMF tones corresponding to #, d₁, d₂, d₃, d₄, d₅, d₆ and * must have a duration as close as possible to 250 ms.  The silent intervals between tones must also each last 250 ms. The sequence of eight DTMF tones should be followed by a silent interval lasting 1.25 seconds (or 1250 ms), after which the 8 DTMF tones repeat followed by another silent 1.25 second interval, and so on. Hence, the whole sequence is played every 5 seconds.

You may ignore amplitude and power considerations between and among tones, but must ensure that the frequencies involved are correct.

Note that the DAC in the analog interface is a 14-bit DAC and that the 2 least significant bits of a 16-bit value sent to the DAC must be zeroed out. Read the TLC320AC01C Data Manual for details.

Be able to answer all questions related to this exercise. During evaluation of this exercise, you must have with you on files or on paper any and all forms of documentation that you would need to show and/or discuss how you went about doing this exercise.

In your lab report, give the significance of all constants involved in tone generation and/or in sequencing the tones. Explain in detail how the tones were sequenced, and how you ensured that the duration of the tones and silent intervals were as specified. Include also details regarding the files names, file sizes, and time stamps of your final source and .obj files.

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