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Original question:

AFE4490 SPI communication and initialization sequences

AFE4490: Issue on AFE4490 start

Cesar Abascal
Prodigy 90 points
Part Number: AFE4490

Hello,

I bought SPO2EVM module and it work very well.

So I decide to design my own AFE4490 custom board. But i'm having problem with it. I can start AFE4490 chip.
I review my board several times and it's consistent with my schematic.

Can you help me?
There is some error on my schematic?

I'm using a Raspberry Pi to communicate with it.

Thank you

  • 0
    TI__Genius 12575 points
    Hi Cesar,

    Can you please tell us more about the error you are facing in out board, is it the chip is not working at all or you have signal quality issue?
    Meanwhile we will review your schematic and get back to you by early next week.

    Regards,
    Prabin.
  • 0 in reply to Prabin Yadav
    Prodigy 90 points
    I guess the AFE4490 isn't working.
    I can't acquire any signal. My AFE4490 supply are okay.

    I realised that I made a mistake on DB9 connector. In this case I had wire wrong the TXN and TXP. Now I fixed my board.
  • 0 in reply to Cesar Abascal
    TI__Genius 12575 points
    Hi Cesar,

    Do you still have issue getting the signal?

    Regards,
    Prabin
  • 0 in reply to Prabin Yadav
    Prodigy 90 points

    Hello.

    In this morning I could fix that problem.

    But now I have another problem.
    I'm using on my custom SPO2 shield the exactly python code that I'm using on SPO2EVM (I made some hack to access SPI communication and I'm using RPi Zero), but on custom SPO2 I'm having 10x less time acquiring. For example, if I capture in SPO2EVM 10 seconds at 200Hz I get 2000 samples. But if I do the same in my custom shield, I'll only get 200 samples. Also, the signal is totally distorted.

    Should I manipulate some other pin in the acquisition? In addition to stePIN?

    Thank you.

  • 0 in reply to Cesar Abascal
    TI__Genius 12575 points
    Hi Cesar,

    To debug this please make sure that you are writing registers with the same value in both the boards. You can read out the registers to verify this ( except register 0). Also check if the oscillators are same. Finally you can probe the ADC RDY pin can confirm that its 200Hz in both the cases.

    Regards.
    Prabin