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ADS7953: Recommendation of best mode to scan all 16 channels as fast as possible and with least amount of software interaction

Randy Perrin
Prodigy 55 points
Part Number: ADS7953

I assume that the Auto1 or Auto2 would be the best solution.  Can you provide some clarification of what mode would be best to implement and why. Thanks for your help. 

  • 0
    TI__Mastermind 24940 points

    Hello,

    you are correct that either of the auto modes would accomplish this. 

    If you are trying to scan through all channel I suggest Auto mode 2.

    To select which one is best for you, it depends on what you are trying to achieve. 

    Auto 1 mode allows you to select which channels, meaning you can omit certain ones. examples, sample Ch 1, 3, 5, 6, 9, 11. in ascending order. 

    Auto 2 mode, which I believe is best for you, will sample all the channels in ascending order, up to the channel you told the device to stop at. so if you say the last channel is 15, then the device will samples Ch 0 - 15 ( in ascending order) 

    Regards

    Cynthia

  • 0 in reply to Cynthia
    Prodigy 55 points

    Cynthia, Thanks for your help. Can you point me to the best place to undersand the SPI inplentation . It seems like quite a burden on the firmware to have to cycle the /CS for every channel. 

  • 0 in reply to Randy Perrin
    TI__Mastermind 24940 points

    Randy,

    The datasheet would be the best place to understand the SPI implementation. Auto2 mode starts on page 38

    I dare say that all devices will require a new frame (CS toggle) to clock out the data from the newly sampled channel data, even if each channel increments automatically. 

    If you are not interested in the output data, but are only interested to make sure that the data is within a certain window or level, then I suggest looking at the ADS7038. This device will sequence through the analog input channels without needing interaction from the host through an internal oscillator. The device also has a window comparator with independently programmable thresholds for each channel. The device will scan through all the channels through the comparator window, and will only trigger an Alert if any of the threshold are crossed. Note that in this mode, autonomous mode, the device will not provide actual conversion measurements. 

    Regards

    Cynthia