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ADS7953: Datasheet issue related to GPIO alarm programming

Sundara Ramanan M A
Prodigy 30 points
Part Number: ADS7953


I am currently trying to program an ADS7953 for Manual mode (no GPIO pins for SDI or SDO) and Alarm setup of GPIO1 for low alarm and GPIO0 for High alarm. But Alarm frame programming has a few incomplete and confusing details. Grouping of Alarm Program Registers (Table 12) outlines the grouping of channels and  In Alarm Program Register Settings (Table 13) the first frame to Select group contains details pertaining DI15-12 and Immediately its followed by DI11-14 as Do not care .Details related to  bits DI10-DI00 is not provided for the first frame .so kindly provide me a clear picture of how to handle Alarm program registers .

Thanks

Alarm program Register settings.pdfads7953.pdf 

  • 0
    TI__Mastermind 25030 points

    Hello,

    It seems there is a discrepancy in the datasheet as you pointed out. I have made a note of it.

    You are trying to use GPIO0 for high alarm and GPIO1 for low alarm, I would point out that table 11 can help set this up, using DIO 6 to 4 that has this set up as a predefined option.

    In table 13, the do not care bits should be D11-0, meaning the rest of the frame is not considered. the flow chart in figure 59 describes the bits that are needed, and only bits 15 to 12 are defined. please note that the correct reference table is Table 13 in this figure, not table 8, which I have also noted.

    Because you are using the 16 channel variant, and if you want to set up all channels, it will take multiple frames to program each channel.

    The first frame will be to enter the alarm register program. The following frame will define what channel within the group to program with what type of alarm (low or high), within this frame, you can select to program the remaining channels in the group channel by setting DI12 =0 . The next frame can be used to program any other channel in the group as defined by DI 15-14  in Frame 2 in table 13.

    Once all four channels in the group are programmed, within the last frame should have D12 = 1. The next frame can then select the next group of channels to program (this would be starting at Frame 1 on table 13)

    A suggested way of going about this is the below.Using the term Frame 1 in reference to table 13, and Frame 2 in reference to table 13. each new line represents a new frame set by falling edge of CS.

    Frame1 = 00 (group0)

    Frame 2 = 00 (lowest channel), alarm selection, D12 =0

    Frame2 = 01 (next channel), alarm selection, D12 =0

    Frame2 = 10 (next channel), alarm selection, D12=0

    Frame2 = 11 (highest channel), alarm selection, D12 = 1

    Frame1 = 01 (group1)

    Frame 2 ….