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AFE4490 driver support required.

Debi Biswal
Prodigy 140 points
Other Parts Discussed in Thread: AFE4490, AFE4403

Hi,

I am using AFE4403 driver for afe4490(back ported). I have modified the register sets as per the afe4490.

We are seeing that probe is successful and the red led on the afe4490 glows.

But now, when we are trying to enable the iio buffer(/sys/bus/iio/devices/iio:device0/buffer/enable) by setting this to 1, we are seeing the below error message.

[  307.501007] Buffer not started: buffer parameter update failed (-22)
-sh: echo: write error: Invalid argument

Please guide on how to resolve the issue.

Thanks,

Debi

  • 0
    TI__Mastermind 18285 points

    Debi,

    We have received your post and hope to have a response back to you soon.

  • 0 in reply to Amy Schnoor
    TI__Mastermind 18285 points
    Debi,

    Can you attach a screenshot of the error?

    Are you using our AFE4490 EVM GUI?
  • 0 in reply to Amy Schnoor
    Prodigy 140 points

    Hi Amy,

    I am not using AFE4490 EVM GUI. I resolved that error by enabling the channel buffers.

    From my afe4490 driver , I am getting some DAC values. By computing those values, I am able to get some heart rate value in BPM(using the sample source for calculating the heart rate provided  in TI health hub heart rate monitor evm)

    In our design we are using the DCM03-AFE4490 as per the reference design,  the issue that we are facing is, without placing the sensor on the wrist, the algorithm computes Heart rate, with the DAC values that we get from the registers. We are using IR LED - IR LED AMBIENT, we also tried the same with LED2 - LED2AMBIENT

    So, we would want to know what settings we have to make for canceling the ambient noise, so that the heart rate should not be computed for this.

     Also we observed that the BPM that we get is always above 100 when the sensor is placed on the wrist. Could you please suggest what settings we should do for the AFE4490.

    We tried the default values as mentioned in the datasheet for AFE4490 as below. We also tried the setting as in EVM that was using AFE4403.


            { AFE4490_LED2STC,  6050},
            { AFE4490_LED2ENDC, 7998},
            { AFE4490_LED2LEDSTC, 6000 },
            { AFE4490_LED2LEDENDC, 7999 },
            { AFE4490_ALED2STC, 50 },
            { AFE4490_ALED2ENDC, 1998 },
            { AFE4490_LED1STC, 2050 },
            { AFE4490_LED1ENDC, 3998 },
            { AFE4490_LED1LEDSTC, 2000 },
            { AFE4490_LED1LEDENDC, 3999 },
            { AFE4490_LED2STC,  6050},
            { AFE4490_LED2ENDC, 7998},
            { AFE4490_LED2LEDSTC, 6000 },
            { AFE4490_LED2LEDENDC, 7999 },
            { AFE4490_ALED2STC, 50 },
            { AFE4490_ALED2ENDC, 1998 },
            { AFE4490_LED1STC, 2050 },
            { AFE4490_LED1ENDC, 3998 },
            { AFE4490_LED1LEDSTC, 2000 },
            { AFE4490_LED1LEDENDC, 3999 },
            { AFE4490_ALED1STC, 4050 },
            { AFE4490_ALED1ENDC, 5998 },
            { AFE4490_LED2CONVST, 4 },
            { AFE4490_LED2CONVEND, 1999 },
            { AFE4490_ALED2CONVST, 2004 },
            { AFE4490_ALED2CONVEND, 3999 },
            { AFE4490_LED1CONVST, 4004 },
            { AFE4490_LED1CONVEND, 5999 },
            { AFE4490_ALED1CONVST, 6004 },
            { AFE4490_ALED1CONVEND, 7999 },
            { AFE4490_ADCRSTSTCT0, 0 },
            { AFE4490_ADCRSTENDCT0, 3 },
            { AFE4490_ADCRSTSTCT1, 2000 },
            { AFE4490_ADCRSTENDCT1, 2003 },
            { AFE4490_ADCRSTSTCT2, 4000 },
            { AFE4490_ADCRSTENDCT2, 4003 },
            { AFE4490_ADCRSTSTCT3, 6000 },
            { AFE4490_ADCRSTENDCT3, 6003 },
            { AFE4490_PRPCOUNT, 7999 },
            { AFE4490_CONTROL1, 0x0101 },
            { AFE4490_TIAGAIN, 0x0000 },
            { AFE4490_TIA_AMB_GAIN, 0x0002 },
            { AFE4490_LEDCNTRL, 0x11414 },
            { AFE4490_CONTROL2, 0x0000 },

    Thanks,

    Debi

     
     

  • 0 in reply to Debi Biswal
    TI__Mastermind 18285 points
    Debi,

    The settings needed to get a good PPG signal will differ depending on the subject. There are many adjustments you can make to the AFE such as TIA gain, LED current, etc. I would suggest adjusting these so that the signal is what you expect. Please keep in mind that these settings will not be the same for every subject.