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Does msp430 dac module dac12_a suitable for wav audio decode?

Tom Cjin
Prodigy 190 points
Other Parts Discussed in Thread: MSP430F5658, MSP430F1611hi, we check the chip msp430f5658 datasheet, there is no description on the parameters that common dac chip descripted,like THD+N, SNR etc. so we doubt that is this dac module suitale for audio decoding? thanks.
  • 0
    Guru 227245 points

    In a recent project, I was using the DAC of the MSP430F1611, running at 8MHz, for output of a nice, clean 50kHz sine wave. Well, the data was precalculated, and moved to the DAC by DMA (4MHz update speed = 80 samples per full wave).But the DAC behaved fine.

    So the DAC (it is more or less the same DAC on all MSPs) is fast enough and precise enough. But Is your code fast enough to do the decode and update the DAC synchronized with sampling frequency?

  • 0
    Guru 34483 points

    Tom Cjin said:
    hi, we check the chip msp430f5658 datasheet, there is no description on the parameters that common dac chip descripted,like THD+N, SNR etc. so we doubt that is this dac module suitale for audio decoding? thanks.

    There is glue logic in slaa449 (Interfacing an I2S Device to an MSP430 Device), that enable MSP430 connection to any I2S standard audio DAC device, but again there is question noted by Jens-Michael about speed of your code.

  • 0 in reply to Jens-Michael Gross
    Prodigy 190 points

    What means code fast ? We use PCM wave file of music , Is it just transfer to DAC  by DMA and okay? 

    If the output analog is fine , so we will do it this way .

     

    We just dont want use another DAC chip , because the MSP430F5658 we used has a DAC module , so we want to use it 

     The datasheet does not descript the performance of the DAC like SNR ,etc , We just worried about the Noise .

    Thanks .

  • 0 in reply to Tom Cjin
    Guru 46710 points

    Tom Cjin said:
    We just worried about the Noise .

    So measure it. All you need is some test code sending test waveforms and quality sound card for computer, also audio quality measurement s/w. As you don't specify what level of SNR is acceptable for you, nobody can tell you anyway - this DAC is OK for you or not.

  • 0 in reply to Tom Cjin
    Guru 227245 points

    Tom Cjin said:
    We use PCM wave file of music , Is it just transfer to DAC  by DMA and okay? 

    i doubt the whole music will fit into flash, so you can set-up the DMA and let it play from start to end.

    And even if, if you have a 100% DMA cycle, the CPU won't work until DMA is complete, so you cannot stop the playback by a button or so.

    But if you want to have DMA and CPOU running in parallel, things get tricky. On a PC, DMA to a sound card is controlled by the sound card and can stop the CPU at any time to do the transfer, to get an equidistant transfer. On MSP things are a bit more difficult. Either DMA runs at full speed (that is, one transfer every two MCLk cycles) or it has to be re-synchronized with the CPU for each transfer. This introduces some jitter. You'll need to synchronize the DAC update as well as the DAM transfer with a timer.
    For longer transfers, you'll have to load and prepare new data in time.

    All this requires a clever hardware setup and efficiently written code. Certainly doable, but the quality of the outcome depends on your skills.more than on the technical data of the hardware.

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