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Interfacing ADS6244 with DSP TMS320C6455

Prodigy 30 points

Replies: 3

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I want to interface the ADC ADS6244 with the DSPTMS320c6455 as I want high speed data capturing for me proto type test equipement. ADS6244 is a 14-bit ADC and having a Serial LDVS output. Can I directly connect it with the SRIO port of the DSP ( or convert it into the CML output suing SN65CML100 ) and store the ADC data in DDR2 RAM (my ADC conversion speed is 105 MHz).

  • Hi,

    The SRIO (Serial Rapid IO) is an 8b/10b coded serial stream.  The serialized data from the ADS6244 is not an 8b/10b coded serial stream.  So no, tjhat would not work. 

    Since the data fromat from the ADS6244 does not have any coding to the data, there must be some way for the receiver to determine where the msb and lsb of a sample is in the serial stream so that the data may be deserialized on the proper bit boundary in the serial stream.  The way the boundaries of the sample bits are determined for the ADS6244 is that there is a parallel data pair that carries a known fixed pattern that starts off with high bits at the start of the sample and finishes with low bits at the end of the sample.  This known fixed pattern is called the frame clock, although you may also think of it as another lane of data that happens to have a fixed pattern, and you use the known fixed pattern on that one data lane to know where to chop up the serial data on all the other lanes into samples.

    SRIO encodes the serial data into code words, and a special code word is used to tell the receiver where the msb and lsb boundaries of the serial data are so that the serial data can be chopped up properly into parallel words of data.

    Regards,

    Richard P.

  • In reply to Richard Prentice:

    Dear Richard,

    If we see the datasheet of the ADS6244, We can program the chip by parallel or serial for the MSB /LSB first and other things (see page 12) and data are sending with bit clock & frame clock(see page 41). Is it not sufficient for the interface with the DSP ? 

     

  • In reply to vrajesh parikh:

    Hi,

    The ADS6244 does allow for a number of different options for the format of the digital data, but none of the possible options match the SRIO, which is the format into the DSP that you first asked about.   All of the possible data formats from the ADS6244 involve a serialization factor of 14bit or 16bit on one LVDS pair or 7bit or 8bit on two LVDS pairs, plus a bit clock and a frame clock.

    I am not aware of any DSP devices that have the flexibility to receive this sort of data format, which i would call a hybrid serial/parallel format being a parallel bus of serialized data lines.  There may be a DSP device somewhere that can receive this format of data, but if so i don't know about it.  It is far more common for the data converter data to go to an FPGA or ASIC first and then possibly to a DSP function. 

    Regards,

    Richard P.

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