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DPLib ADC single vs multi channel driver

TobyM
Genius 5200 points
Other Parts Discussed in Thread: CONTROLSUITE

Hi

I'm working my way through the DPLib module's user guide and wonder is there any advantages or disadvantages to be had by using single or multi channel ADC drivers?

(other than the fact that the multi channel driver can only have one instance)?

i.e. If I need 5 ADC channels why would I use a single 4 channel driver and single 1 channel driver over five single channel drivers, or vice versa?

Thanks

  • 0
    TI__Guru 57255 points

    Toby,

    The 4ch driver is more cycle and code size efficient.  The 1ch driver is more flexible.

    For example four 1ch drivers will use 20 cycles and will take up 52W of code size whereas one 4ch driver will use 14 cycles and 28W of code size.  This difference won't be important in many applications, but for something like a multi-phase DC/DC it may be (where ISRs can be >200kHz and many ADC samples need to be taken within the ISR).

    The numbers shown above were taken from the "DP Library Function Summary" table within the documentation for the F2803x digital power library v3.3.


    Thank you,
    Brett

  • 0 in reply to Brett Larimore
    Genius 5200 points

    Thanks for that answer Brett,

    I actually have another quick question, looking at the Multi DC/DC color LED code example, I am not sure how a reference startup ramp is being implemented - is this to do with the "slew rate" I see mentioned (I havent figured out exactly how that is used yet either)?

    Is there a document that goes into a bit more detail on the actual program structure than the app note that is included in the example folder? e.g. something that may explain the time slicing implementation etc

    Thanks

  • 0 in reply to TobyM
    TI__Guru 57255 points

    Toby,

    Yes the SlewStep variables variables will add (or subtract) some defined amount from the reference every so often in the slow state machine loop within the Main file.  For this particular project it will happen every "Period of CpuTimer0 in seconds" * "Number of A Tasks" = 2ms.

    A good reference for the program structure within this project is inside controlSUITE in the following area:
    \controlSUITE\development_kits\TemplateProjects\~Docs\SystemFrameworkOverview.pdf

    Hopefully this helps some.


    Thank you,
    Brett