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MSP430 launchpad with DTMF

yogeswaran sundarraj
Prodigy 30 points

Can any one help me implementing DTMF detector algorithm on MSP430 Launchpad

  • 0
    Guru 58965 points

    The second half of: http://www.ti.com/lit/an/slaae16/slaae16.pdf may be of use to you.

    But if you are limited in doing c-program only and knows nothing else, you may have a hard time.

  • 0
    Mastermind 7925 points

    I would use special IC. It is not the cheapest solution but should be more reliable.

    Ex:  HT9170 DTMF Receiver (seach Mouser/Farnel).

    Regards,
    Maciej 

  • 0 in reply to MaciejKucia
    Guru 46710 points

    MaciejKucia said:
    Ex:  HT9170 DTMF Receiver (seach Mouser/Farnel).

    I strongly disagree that this more than 10 years old part that uses switched cap filters for freq detection can be superior to DSP approach. Using HT9170 will be just waste of money.

  • 0 in reply to Ilmars
    Mastermind 7925 points

    Ilmars said:

    I strongly disagree that this more than 10 years old part that uses switched cap filters for freq detection can be superior to DSP approach. Using HT9170 will be just waste of money.

    The "DSP" approach needs more than few passive components. The DTMF technology itself is not young. 
    Ilmars, do you think that performance of DSP approach would be better? I do not see any disadvantage of the IC except price. In the future availability might be a problem as well, but at the moment I can see some chips available at Farnell. Thanks for any comments on this.
    The IC I proposed is the easiest and most compact solution but indeed far from perfect.
  • 0 in reply to MaciejKucia
    Guru 46710 points

    MaciejKucia said:
    I do not see any disadvantage of the IC except price

    That's the beauty of microcontrollers - that you can do so much in software. Extra functions will cost you more cpu power and more flash which is anyway much less increment than to use specialized IC. In this case you can do even better in uC than in this venerable IC ;)

    MaciejKucia said:
    most compact

    Disagree here. You need uC anyway, so software solution will be most compact solution imaginable.

  • 0 in reply to Ilmars
    Mastermind 7925 points

    I must agree with you. I have spent some time looking into app note old_cow_yellow posted. Figure 22: "Circuit diagram showing coupling in of signals to the ADC" shows receiver schematic that is much simpler than external IC.

    Regards,
    Maciej 

  • 0 in reply to MaciejKucia
    Guru 35525 points

    MaciejKucia said:
    It is not the cheapest solution

    That depends on how you cost the development time to do it in software!

    Maybe getting it done soonest is more important than getting it done cheapest...

  • 0
    Prodigy 70 points

    Hi,

    Iti s a bit late response but you should consider using Goertzel algorithm.

    It is far more efficient as FFT if you need fewer frequencies on a low power MCU as long as you use fixed point.

    I am working on similar project in my spare time, so it will took a while. But it will most likely end up being OSHW.

    Here are a few links to start from:

    www.ti.com/ww/cn/uprogram/share/ppt/c6000/Chapter17.ppt

    http://en.wikipedia.org/wiki/Goertzel_algorithm

    Also if you are more familiar with using math lab for algorithms. You can test it up in matlab and transfer it to CCS. (Remember to use FIXED point, because msp is no match for so much floating point conversions)

    http://www.mathworks.com/hardware-support/ti-ccs.html

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