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ADS1258: I AM NOT ABLE READ DATA FROM ADC IN DIRECT DATA READ(NO COMMAND)

Naresh naresh
Intellectual 535 points
Other Parts Discussed in Thread: ADS1258

Hello..  

I am working on ads1258 with fpga this is first time i am working with ads1258 . i go through the data sheet in that i selected to direct data read(no command) .

i am making a spi_sclk (spi clock)as continuous and chip selcet as low and mosi as low.i never makng chip select as high .

i want to know how to read the data from the miso line .if  it send the 4 byte of data for every BITS CHID  (or) how it will work .

can you help me with direct data read please ?

  • 0
    TI__Guru 52516 points

    Hi Naresh,

    The first sign of life to look for is /DRDY going low. If you've properly powered the device, applied the clock, and set the GPIO pins appropriately, then /DRDY should become active. You'll first notice it go low, and then it will begin to pulse at intervals of the ADC data rate (as shown in figure 56 of the datasheet).

    Since you're not using an external crystal on the XTAL1/XTAL2 pins, then you'll need to set CLKSEL high and apply a 16 MHz clock to the CLKIO pin (as shown in figure 40).

    At the moment it would sound like either the external clock or the GPIO pins (START, nPWDN, nRESET) are not configured correctly. I think once you get those set, you'll see the device come to life.

    -Bryan

  • 0 in reply to Bryan Lizon86
    Intellectual 535 points

    Hello Bryan ..

    Thank you very much for replaying back to my query..

    IN direct data read (No command )

    Suppose if i  have 16 channels i connected to adc so intially adc drdy is in low if i give sclk on first falling edge it will return to high . so please tell me how many sclk pulses i need to give . 

    1.one more query i have suppose if a change any ANI0 to something what will happen then how would i read.

    2. please provide any example timing diagrams for the direct data read(No command).

    3.when the device in direct data read (No command ) it will send entire 29  BITS CHID  data into the miso line are how it works.

    4.tell me how to read the data in direct channel read (no command )

    5.please tell me how to set the pwdn,start,reset ,clksel pins 

  • 0 in reply to Naresh naresh
    TI__Guru 52516 points

    Hi Naresh,

    I believe you opened another thread on this same topic, so I will defer to answering your questions there. Please only open 1x thread per topic, or it will be challenging to provide support. Thanks!

    -Bryan