EVAL-ADPD1081Z-PPG read sensor data

Hi support team

As you can see, I add the LED2, LED3 current from 5mA to 170mA

But the response of the sensor is almost the same.

I did not understand why l see almost the same photodiode response.

Is there any setting wrong ?

best regards

  • 0
    •  Analog Employees 
    on Oct 28, 2020 7:55 PM 26 days ago

    It is most likely some wrong setting with timing configuration or channel configuration. Could you please send your configuration file? I will try to help.

    Also could you please try to sweep the LED current with small steps and summarize what you see?

  • Hi support:

    I attach the file link.

    This setting is given by FAE.

    I do not know what setting is wrong.

    best regards

  • 0
    •  Analog Employees 
    on Oct 29, 2020 5:29 AM 26 days ago in reply to future


    You should work with your field apps person as they are the responsible people to get you up the speed. So, please be in touch with them frequently. 

    With that out of the way, the only channel that is enabled is CH1 of Timeslot B. And that is set to block average of N samples and 32-bit sum of all four channels. That's why you don't see any change at all for CH2,3 and 4. There is also nothing (no photodiode) connected to them, so what you see on those channels is garbage. Since it is block average on CH1, it's just averaging pulses. If you want to see a change, you should write Reg 0x11 bit 13 to 0. So, that will make reg 0x11 to 0x10A0. You will have change only in CH1. 

    You should consult to the ADPD1080 datasheet and your FAE in order to decide how to receive the output from the device. 

  • Hi Yigit Yoleri :

    I want to do some experiment for Red , IR LED.

    But I found the three green LED is connected to the same LEDX1.

    There is two more LED driving channel for use.

    But I can not use eval-adpd1081z-ppg to do this experiment.

    So I can not change LED2, LED3 to Red , IR LED.

    The only way is to cut the wire.

    And jump wire to LEDX2, LEDX3.

    Is there any shortcut for change LED2, LED3 to Red, IR LED and driving them?

  • 0
    •  Analog Employees 
    on Nov 3, 2020 1:25 AM 21 days ago in reply to future


    I found another version of EVAL-ADPD1081Z-PPG board and I want to make sure which version you have. The documentation (eval board user guide) is a bit old, so you may actually have received the newer version. 

    In the newer version, the spare pad that you see in the picture you attached is filled with a red and an IR LED. If you turn on the LEDx2 driver, is there a red light coming from the board? The red LED is attached to LEDx2 in this new board version. I attached the new board schematic in PDF at the end of this message.

    If there is no red light coming from the board, it means you have the old version that is on the user guide. Then what you do is to use that spare pad to solder red and IR LED. You could use a red and IR LED module like this one:


    By the way, for the best noise performance, I recommend you to check the newest AFE from Analog Devices, that is superior to ADPD1080.This new AFE is called ADPD4100.We recommend this AFE for new designs, especially it's much better for wrist SpO2 measurements.