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AFE4490 adc convertion ready

Tikhon Uglov13
Prodigy 10 points
Other Parts Discussed in Thread: AFE4490

Hello,

I'm able to communicate with AFE4490 by SPI. Are there any registers from which I can know that ADC conversion is ready?

Here http://e2e.ti.com/support/applications/high_reliability/f/30/p/290393/1013308 you write: "Read ADC registers (0x2A – 0x2F)             –             from host controller either polling based or interrupt based (ADC_RDY signal interrupt)". What does "polling based" mean?

Best regards,

Tikhon.

  • 0
    TI__Expert 6320 points

    Tikhon,

    We have received your post and will be responding soon.

    Thanks,

    Chuck

  • 0
    TI__Mastermind 49176 points
    Hello Tikhon,

    No there is no register bit that indicates the ADC conversion is ready.
    You will need to read the ADC registers based on the ADC_RDY interrupt.

    Thanks for pointing out the previous post about the polling method.
    The polling method refers to monitoring the ADC_RDY signal for the pulse. But since the ADC_RDY pulse width is only 250ns wide, this technique will not work. I have updated the original post.
  • 0 in reply to Praveen Aroul
    Prodigy 130 points
    Hi,

    I have few questions on ADC_Ready. I am using the AFE44x0SPO2-FE Demonstration Kit (along with supplied probe). Removed the resistors (SPI interface is connected to my controller).

    Initialization as mentioned in datasheet. (Followed the steps as per Figure 3. Supply Ramp and Hardware Power-down timing)

    1) RESET pin = 0
    2) delay 100ms
    3) AFE_PDN = 1; Release the power down
    4) delay 200ms
    5) RESET pin = 1
    6) delay 100ms
    7) Configure Transmitter, ADC, Receiver
    8) configure the counter (PRP = 500Hz, all the counters were intialized as per datasheet provided values)
    9) Enabled the timer/counter (Control 1 register TIMEREN)
    10)Enabled Read.

    ADC_RDY pin is connected to my controller's external interrupt pin.
    Issues:
    1) Sometimes the interrupt is not generated.
    2) Sometimes interrupt gets generated. I could able to read the ADC values. The count seems to be proper. But after some time all the ADC counts are read as 0.
    3) On enabling the diagnostics, (before step 7), the Values read from DIAG register are 0x00, 0x1E, 0x20.

    Is there anything that I missing here?
    1) Why the faults are generated in the eval kit.
    2)Why ADC_RDY is not generated all the time?
    3) On any faults, whether the ADC counts will be 0?

    Regards,
    Purushottam