Why is the PPG Signal acquired by the AFE 44x0 GUI software on the LED IR seems like a mirror image of what it should be?

Soumya Chakraborty

Other Parts Discussed in Thread: MSP430F2274, AFE4400

I have just hooked on my brand new AFE 4490 board to the computer and just got results which are quite similar to look at as those shown on your Page 36 of the AFE 4490 EVM Development Guide.I captured a few data points (Voltages) in an excel file and tried a moving average with an windows of 8 to try and remove the 0.5 Hz to 5 Hz. Unfortunately the shape of data remains t he same. In reality the PPG signals should look like the one shown below:

Please let me know where am I going wrong??

over 8 years ago

0 Amy Schnoor over 8 years ago

TI__Mastermind 18275 points

Soumya,

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

0 Soumya Chakraborty over 8 years ago

Prodigy 60 points

Dear All,

I am flummoxed, the PPG signal conventionally is the one shown in my previous message, where the dicroctic notch is on the right of the peak, however, in the AFE generated signal the dicrotic notch is appearing left of the peak. The dicrotic notch should appear on the right after the peak as it happens after it. Please explain as in your case the dicrotic notch appears to happen before the peak:

0 Amy Schnoor over 8 years ago in reply to Soumya Chakraborty

TI__Mastermind 18275 points

Soumya,

This e2e post might help you understand the PPG measurement from the AFE.

e2e.ti.com/.../420969

0 Soumya Chakraborty over 8 years ago in reply to Amy Schnoor

Prodigy 60 points

Thanks Amy, the answer was very helpful. It made sense to set an upper threshold and subtract the PPG Values and the new PPG Values look realistic.

0 Divya A N over 8 years ago in reply to Soumya Chakraborty

Prodigy 110 points

Hi
Can i get the code for AFE4400 interfaced with MSP430F2274 for acquiring PPG signal.
Please kindly help me. Am stuck with my code

0 Amy Schnoor over 8 years ago in reply to Divya A N

TI__Mastermind 18275 points

Divya,

We provide the source code for our EVM and that can be found on our product folder under "Tools & software"

www.ti.com/.../toolssoftware

0 Eyal Teerosh over 7 years ago in reply to Amy Schnoor

Prodigy 10 points

Hello Amy,

Can you please fix that link?
I want to hear that answer as well :)

0 Prabin Yadav over 7 years ago in reply to Eyal Teerosh

TI__Genius 12555 points

Hi Eyal,

Here is the link:
e2e.ti.com/.../1500265

Regards,
Prabin.

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Why is the PPG Signal acquired by the AFE 44x0 GUI software on the LED IR seems like a mirror image of what it should be?