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AFE4400: Questions about AFE4400 Chip Cable Off Detection

Jingjie Li
Prodigy 10 points
Part Number: AFE4400

Hello,

I'm currently developing something using AFE4400.

I found that when normally running, the PD_ALM and LED_ALM Pins are always 0v even when I unplug the SpO2 cable. 

I tried to set CONTROL0 Reg to enable Diagnostic Mode, still nothing in those two pins. What should I do to robustly read out cable off alarm from  PD_ALM and LED_ALM Pins?

best,

jingjie

  • 0
    TI__Genius 12575 points
    Hi Jingjie,

    Following can be the reasons for your observations.
    1) AFE is not functioning: Make sure that AFE is programmed with all the blocks enabled and functioning properly. You can probe the ADC_RDY pin to confirm this. There should be pulse trains on ADC_RDY pin with the frequency same as PRF.
    2) Insufficient Wait time: Ensure you wait for ~16mS before you probe PD_ALM and LED_ALM. Please also probe DIAG_END pins also

    You can also know the result of the diagnostics by reading the diagnostic flags.

    Regards,
    PRabin