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ADS803-Interfacing with microcontroller

Guillermo Pocetti
Prodigy 150 points

Hi,

 How is the best way to interface this AD with a microcontroller, since It doesn't have any syncro signal such as "convertion done"? I was thinking of using an external clock provided by a crystal oscillator for the AD and then connect it also to a GPIO of the microcontroller and use it to syncronize with the AD, that is to say, read data of the parallel output everytime there is a rising edge (by interruption) of the clock (taking into consideration the 6.5 clock cycles of data latency and the new data delay time).

PD: As it is a pipelined architeture, would you recommend it for a high resolution ultrasonic distance measurement ??

Thank you very much,

Best regards

  • 0
    TI__Mastermind 29220 points

    Hi,

    The data output, like almost all of our high speed ADCs, is simply a continuous stream of samples.  Whatever device the data goes to has to have a simple input bus of parallel data bits plus clock, and be able to clock in a continuous stream of samples and keep up with the clock rate.  Most newer ADCs have a clock output pin that goes with the sample data bus and meets some guaranteed setup/hold timing, but older devices like this make you use a copy of the sample clock to clock the sample data into the next device.

    If the microcontroller has a general purpose input port with electrical and timing characteristics that can accept a parallel data bus with clock from the ADC, then you can use the ADC output into the microcontroller.  On our EVMs for these devices, we often have a buffer device (such as a SN74AVC16244DGGR or something similar) that buffers out the sample data plus a copy of the sample clock.  it would be up to you to see if that would meet timing into the downstream device.

    Most commonly, we see an FPGA used to accept data from a high speed ADC and then reformat or retime the data to make it suitable to be handed off to the next device, but at the relatively low speed of this device, you may find you can meet timing into a simple GPIO bus without needing an FPGA in the middle.

    And now that I look at it, this ADC is actually supported by our precision data converter group, not the high speed data converter group, although there are some high speed data converters with same or similar pinout.  I should move this posting over to the precision data converter forum.

    As far as I know, if the device specifications in the datasheet meet your needs for your ultrasonic distance measurement application, then I don't think the pipelined architecture of the ADC would matter.

    Regards,

    Richard P.