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ADS124S08: Interfacing the ADS124S08 with STM32 Discovery board

Mangesh Shirsath
Prodigy 40 points
Part Number: ADS124S08

Hello team, i am trying to interface the ADS124S08 with stm32f407 and tried to communicate but while reading the register of adc it gives me 0xff at miso pin i dont know to work with that ans what clock configuration i need to set so that communication will work fine. Loking for your positive response. Thanks in advance.

  • 0
    TI__Guru** 113765 points

    Hi Mangesh,

    Welcome to the E2E forum! The best way to troubleshoot communication issues is by using an oscilloscope or logic analyzer to view the communication.  Do you have some shots of your communication that you can share?  The most common mistakes are:

    • Using too fast of an SCLK frequency.  The maximum is 10MHz, but I suggest using 1MHz when prototyping.
    • Using the wrong SCLK idle and phase.  The SCLK should idle (or dwell) low when not clocking, and the data should change on the rising edge of SCLK and hold steady to be read on the falling edge of SCLK.  This is often considered Mode 1 SPI.
    • The CS must be held low throughout the entire communication transaction (or all bytes of the transfer).  If the CS signal toggles on every byte the communication will cancel and reset the SPI bus.  This timing is shown in the ADS124S08 datasheet.

    Best regards,

    Bob B

  • 0 in reply to Bob Benjamin
    Prodigy 40 points

    Thanks  @Bob Benjamin, I had set Mode 1 of SPI and  and SCLK is at 1.5Mhz Seems good when i am writing to the ADC but There is no output data on MISO pin. 

    For the reference i am sharing the SS in short you will get the idea,

    • And when i am trying to read the data from the register is gives me zero output.   
  • 0 in reply to Mangesh Shirsath
    TI__Guru** 113765 points

    Hi Mangesh,

    I'm not sure what you are trying to accomplish here by writing the POR state to the Status register.  When writing to the Status register you would generally write 0x00 to clear the bit showing the POR has completed.  Instead of writing the Status register have you tried reading it first to see if the POR has completed and that the ADS124S08 is ready to communicate?

    Also verify that the RESET pin is pulled high, the CLK pin pulled low and all supplies (DVDD, IOVDD and AVDD) are operating at the nominal voltages.  By reading the Status register first, the MSB should show a high which means that the ADS124S08 is fully operational and has released from the POR state.  If it is low, then the ADS124S08 is still in the reset state.  Once the device has completed POR, you should be able to communicate with the ADC for configuration.

    Best regards,

    Bob B