AD7683 and Sampling clock

Hi,

I need to know how to vary the sampling frequency of AD7683?

It is written that the sampling clock is internal.

I need to use this for 1KHz and 256Hz sampling,is this possible?

Parents
  • Hi,

    I am bit confused.

    My application is automotive diagnostic,telematics and measurement,ECU related etc.4 Bridge Sensors then MUX(4:1 x2) and instru AMP and a ADC.

    I need to detect vibration,shock,sudden accleration and tri axial accleration.

    I am in selection process.As you know automotive application is cost sensitive especially in India.

    Presently I am using BF537.

    See if I assumed TIM's explanation that the ADC conversion process is CS/ dependant.You make 1KHz timer and in its interrupt just do a SPI read of the device which will automatically make the CS/ low and SPI clock will be in MHz may be as he suggest 2.9MHz so I willl get the result in SPI data register of the processor.

    This brings me back to the same question how the device knows the samplig clock ? as 2.9MHz is just a communication clock or is it that the device will sample in the intervals of 1KHz but sampling clock of 2.9MHz.So sampling bursts of 2.9 MHzs at 1KHz something like that.

    As per Maithil 22 times the serial clock is the sampling clock,

    2.9MHz / 22 does not make 100Ksps. I think it will be 2.2 MHz clock to get 100 Ksps and for 1Ksps 1K*22 = 22KHz so again pretty slow SPI clock needed.

    This again makes me think that this particular device is may be for Single Shot mode only.Was this device targeted to particular OEM and not for a general market?

    I request both of you to express your thoughts, I am bit slow on things.

Reply
  • Hi,

    I am bit confused.

    My application is automotive diagnostic,telematics and measurement,ECU related etc.4 Bridge Sensors then MUX(4:1 x2) and instru AMP and a ADC.

    I need to detect vibration,shock,sudden accleration and tri axial accleration.

    I am in selection process.As you know automotive application is cost sensitive especially in India.

    Presently I am using BF537.

    See if I assumed TIM's explanation that the ADC conversion process is CS/ dependant.You make 1KHz timer and in its interrupt just do a SPI read of the device which will automatically make the CS/ low and SPI clock will be in MHz may be as he suggest 2.9MHz so I willl get the result in SPI data register of the processor.

    This brings me back to the same question how the device knows the samplig clock ? as 2.9MHz is just a communication clock or is it that the device will sample in the intervals of 1KHz but sampling clock of 2.9MHz.So sampling bursts of 2.9 MHzs at 1KHz something like that.

    As per Maithil 22 times the serial clock is the sampling clock,

    2.9MHz / 22 does not make 100Ksps. I think it will be 2.2 MHz clock to get 100 Ksps and for 1Ksps 1K*22 = 22KHz so again pretty slow SPI clock needed.

    This again makes me think that this particular device is may be for Single Shot mode only.Was this device targeted to particular OEM and not for a general market?

    I request both of you to express your thoughts, I am bit slow on things.

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