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Connection ADS1178 to OMAP-L137

sbartoszek
Prodigy 110 points
Other Parts Discussed in Thread: ADS1178, OMAP-L137

Hello.
I work with EVMOMAP-L137 and ADS1178EVM.
How do I connect the ADS1178 converter to the processor to read a few-second sequence of samples? I would like to use DMA, so as not to block the processor.

I tried to use the SPI, but I don’t know how to get the synchronization. I connected DRDY with SPIx_ENA, but it does not work correctly, because DRDY goes to high after first clock tact.

Further ideas that come to mind are: ADS1178 configuration in master mode (slave mode processor) or use Frame Sync interface.
Is it possible to use of this communication McASP interface?

Please help in this regard.

  • 0
    TI__Guru**** 189401 points

    Hello,

    I moved your post from the Audio Converter (ADS1178 is not an audio converter) to the OMAPL1x Processors Forum. I hope they can help you, or at least get you to the right people.

    Sorry for the run-around.

    -d2

  • 0
    TI__Genius 14545 points

    I wouldn't recommend using McASP for this application since the OMAP-L137 has a dedicated SPI interface as you aware of.

    I'm not all that familiar with the ADS1178, but from the datasheet, it appears as though the DRDY pin is driven active low to indicate that the device has another sample ready -or- immediately after a mode change, otherwise it is driven high when it is operating in SPI mode. This seems to be consistent with your observation.

    From the OMAP-L137 datasheet, SPI_ENA is an output only when the processor is a SPI bus slave. It is an input when the processor is the SPI bus master. The SPI_ENA is used to delay the start of the next slave transfer until SPI_ENA is driven low by the slave.

     

    This seems to be exactly what you want in that the SPI transfers are delayed until the slave is ready to send another transfer (DRDY going low). Am I missing some level of detail here on why this wouldn't work? Let me know.