How to verify and get accurate IR LED data of AFE4400 for Heart Rate measurement application?

Ajinkya R. Shinde

Other Parts Discussed in Thread: CC3200, AFE4400, AFE4400SPO2EVM

Hello,

I have successfully interfaced AFE4400 chip of AFE4400SPO2EVM with CC3200 Simple-link micro-controller.

Now I am reading LED1_ALED1VAL (IR LED - LED1AMBIENT Value) for Heart rate measurement.For that, I have checked the waveform of LED1_ALED1VAL on PC HRM software setting PRF value by 200Hz and for 500Hz . So I got 30 bpm value for 200Hz (5 ms sampling rate) and 60 bpm for 500Hz (2ms sampling rate).

Above reading shows that measurement is not accurate, where I am looking forward to achieve near about accurate HR measurements.

So, please let me know how to achieve accurate measurement for HRM like by Filtering data or any adjustments in AFE4400 registers values.

Best Regards,

Ajinkya Shinde

over 8 years ago

0 Amy Schnoor over 8 years ago

TI__Mastermind 18275 points

Ajinkya,

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

0 Ajinkya R. Shinde over 8 years ago in reply to Amy Schnoor

Intellectual 385 points

Hello Amy,

Thanks for consideration. Also I would like to know, if I chang the TIA Gain register setting will help to get more HRM accurate result or not.

Because When I changed the TIA gain 0 db to 3 dB or to 6 dB, gives me somehow more accurate result. So can you explain me effects of TIA gain on measurement? or How the TIA Gain working?

Waiting for your answer.

Mit freundlichen Grüssen,
Ajinkya Shinde

0 Amy Schnoor over 8 years ago in reply to Ajinkya R. Shinde

TI__Mastermind 18275 points

Ajinkya,

It depends. You should try to get at least 1mV AC for accurate HRM results. TIA gain will help you achieve this.

The receiver front end has the TIA that converts the current from the photodiode into an appropriate voltage. This is shown in Figure 34 of the datasheet. Refer to section 8.3.1 for more information on the Receiver Channel.

0 Ajinkya R. Shinde over 8 years ago in reply to Amy Schnoor

Intellectual 385 points

Hi Amy,

Your last post was very much helpful. Can you please clarify the sentence "You should try to get at least 1mV AC for accurate HRM results."

What is 1mV AC, where I can measure AC?

Please reply ASAP. required urgently.

Best Regards,

Ajinkya Shinde.

0 Amy Schnoor over 8 years ago in reply to Ajinkya R. Shinde

TI__Mastermind 18275 points

Ajinkya,

AC is the peak to peak voltage on the PPG signal

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How to verify and get accurate IR LED data of AFE4400 for Heart Rate measurement application?