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?

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  • Hello Maithil,

    Yes this makes lot of sense.I will not use AD7683 for sure thanks for AD7685 suggestion and explanations.

    My team is trying to read AD7683 and BF537 EZ kit over SPI.It looks like it is not possible to read this on BF537.

    When we connected a FPGA and with which we can generate any type of serial interface,so we generated timings similar to what is mentioned in Datasheet,we got the results.

    Blackfin will never be able to generate such timings over SPI.

    This is the precise reason because of which you might be using Altera eval board.

    Data sheet probably means Glued compatiblity with BF53x.

    Has anyone performed a SPI read of AD7683 over BF53x?16 bit SPI register and 24 bit clock requirement for 16 bit data?

    What we can do here is put CS/ low and read it three times in 8 bit SPI mode and keep doing this continuously as we need to supply the clock.

    I don't know whether this will work?

    Before I do similar exercise over AD7885,I just need to ask you a very simple question:

    1.Can we interface AD7885 gluelessly to BF53x?

    2

    CNV, which initiates the conversions, to be independent of the readback timing (SDI).

    What is the meaning of that?

    Do I have to do a Low high and Low of the CNV?

    In SPI most of the Time the CS/ or CNV will be high so what will the device will do,keep continuing the conversion??And of what data?old acquired data again?

    When we use DMA reads,I don't think we can play with CS/ and toggle it between every read.

    Pls tell me suitable method to do a simple typical BlackFin SPI read of the device.

    .

Reply
  • Hello Maithil,

    Yes this makes lot of sense.I will not use AD7683 for sure thanks for AD7685 suggestion and explanations.

    My team is trying to read AD7683 and BF537 EZ kit over SPI.It looks like it is not possible to read this on BF537.

    When we connected a FPGA and with which we can generate any type of serial interface,so we generated timings similar to what is mentioned in Datasheet,we got the results.

    Blackfin will never be able to generate such timings over SPI.

    This is the precise reason because of which you might be using Altera eval board.

    Data sheet probably means Glued compatiblity with BF53x.

    Has anyone performed a SPI read of AD7683 over BF53x?16 bit SPI register and 24 bit clock requirement for 16 bit data?

    What we can do here is put CS/ low and read it three times in 8 bit SPI mode and keep doing this continuously as we need to supply the clock.

    I don't know whether this will work?

    Before I do similar exercise over AD7885,I just need to ask you a very simple question:

    1.Can we interface AD7885 gluelessly to BF53x?

    2

    CNV, which initiates the conversions, to be independent of the readback timing (SDI).

    What is the meaning of that?

    Do I have to do a Low high and Low of the CNV?

    In SPI most of the Time the CS/ or CNV will be high so what will the device will do,keep continuing the conversion??And of what data?old acquired data again?

    When we use DMA reads,I don't think we can play with CS/ and toggle it between every read.

    Pls tell me suitable method to do a simple typical BlackFin SPI read of the device.

    .

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