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Interfacing ADS8422 with TMS320C6474

Epic Vancouver
Intellectual 885 points

Other Parts Discussed in Thread: TMS320C6474, ADS8422, ADS8413, ADS5231, PCF8575

Hey there,

What would the best way to interface 12 x ADS8422 with one TMS320c6474?

Would I need an FPGA to do this or can I connect these ADCs directly to the DSP?

thanks,

EV

  • 0
    TI__Mastermind 18130 points

    You will need some sort of arbitration logic between all the ADCs and the DSP. These ADCs output 16-bit data over a parallel bus and the C6474 does not have a wide enough parallel port to accomodate all of them simultaneously. An FPGA is one example of a method to accept the output from each part and send them to the DSP one (or more) at a time.

  • 0 in reply to TimHarron
    Intellectual 885 points

    Tim,

    If the ADC has a serial output like the ADS8413, what would be the best way to interface 12xADS8413 to the C6474.

    thanks,

    EV

  • 0 in reply to Epic Vancouver
    TI__Mastermind 18130 points

    I don't think I'm going to be able to give you the 'best' answer, but I will do what I can to help with 'an' answer [:)]

    The ADS8413 runs at 2MSPS so with 12 of these you are looking at 24MSPS. When multiplying this by the resolution (16 bits) you are looking at a throughput of 384Mbit/sec. This is a lot of throughput for a serial data stream, and our McBSP cannot handle this much throughput. This means you are still looking at some form of external logic to help arbittrate the data transfer into the DSP.

  • 0 in reply to TimHarron
    TI__Intellectual 1680 points

    A very efficient way to connect high speed data converters with C6474 consists of using a part from IDT 80HFC1001 which is a CPRI to TDM bridge. See http://www.openbasestation.org/newsletters/july2008/idt.htm it relates to TCI6488 which shares lots of interface with C6474. It works very nicelly with parts like the ADS5231/32.

    In the case of ADS8422, you may want to add some basic logic at the bridge TDM ports to cope with the large amount of data converters you want to trigger.... GPIOs or even a GPIO expander (i.e PCF8575) can help also.

    From the SW side of view, you can use the basic example from the C6474 CSL setting up an AIF link in CPRI mode to record your data conversion values. the 80HFC1001 has to be configured over I2C, also easy with a C6474.

    I hope it helps !