AFE4404 in one LED Mode

Samuel Conti

Other Parts Discussed in Thread: AFE4404

Hello,

I use the AFE4404 to read the heartrate at wrist. I included the AFE4404 library in my project and I acquire a clean PPG signal, the library is able to calculate the HR correctly, of course when I'm static (without motion artefact).

As the timing engine of the AFE4404 is for 3 LED + 1 ambient I would like to optimize this to program it for 1 LED + 1 ambient. First I program the 2 unused LED with 0mA current (and it works) but I would like to do better deactivating unused timing engine part of the AFE4404 of these 2 LED especially the activation, the sampling and the ADC conversion of the LED (I keep the ADCRSTx as it's mentioned p24 in order to keep the ADC_RDY pulse). The aim is to increase the PDN length of the cycle. But with this manner the ADC_RDY pulse is no more generated.

So can you check my timing engine to see if there's an error ? or maybe my manner to do is not possible...

Action : Register start (hexa) / Value (dec) ; Register end (hexa) / value(dec)

- Activate LED 2 : 0x09 / 0 ; 0x0A / 0

- Sampling LED 2 : 0x01 / 0 ; 0x02 / 0

- ADC Reset 0 : 0x15 / 0 ; 0x16 / 6

- ADC Conversion LED 2 : 0x0D / 0 ; 0x0E / 0

- Activate LED3 : 0x36 / 0 ; 0x37 / 0

- Sampling LED 3 : 0x05 / 0 ; 0x06 / 0

- ADC Reset 1 : 0x17 / 7 ; 0x18 / 13

- ADC Conversion LED 3 : 0x0F / 0 ; 0x10 / 0

- Activate LED1 : 0x03 / 14 ; 0x04 / 413

- Sampling LED 1 : 0x07 / 94 ; 0x08 / 413

- ADC Reset 2 : 0x19 / 415 ; 0x1A / 421

- ADC Conversion LED 1 : 0x11 / 422 ; 0x12 / 881

- Sampling LED amb : 0x0B / 493 ; 0x0C / 812

- ADC Reset 3 : 0x1B / 883 ; 0x1C / 889

- ADC Conversion LED amb : 0x13 / 890 ; 0x14 / 1349

- PDN Cycle : 0x32 / 2149 ; 0x33 / 39199

Best Regards,

Sam

over 7 years ago

0 Praveen Aroul over 7 years ago

TI__Mastermind 49176 points

Hi Sam,

A ideal way to turn off conversions and still ensure the internal digital state machine works fine is to provide at least 1 clock cycle for the conversions.

I have highlighted the timing changes in red below.

Action : Register start (hexa) / Value (dec) ; Register end (hexa) / value(dec)

- Activate LED 2 : 0x09 / 0 ; 0x0A / 0

- Sampling LED 2 : 0x01 / 0 ; 0x02 / 0

- ADC Reset 0 : 0x15 / 0 ; 0x16 / 6

- ADC Conversion LED 2 : 0x0D / 7 ; 0x0E / 7

- Activate LED3 : 0x36 / 0 ; 0x37 / 0

- Sampling LED 3 : 0x05 / 0 ; 0x06 / 0

- ADC Reset 1 : 0x17 / 8 ; 0x18 / 14

- ADC Conversion LED 3 : 0x0F / 15 ; 0x10 / 15

- Activate LED1 : 0x03 / 14 ; 0x04 / 413

- Sampling LED 1 : 0x07 / 94 ; 0x08 / 413

- ADC Reset 2 : 0x19 / 415 ; 0x1A / 421

- ADC Conversion LED 1 : 0x11 / 422 ; 0x12 / 881

- Sampling LED amb : 0x0B / 493 ; 0x0C / 812

- ADC Reset 3 : 0x1B / 883 ; 0x1C / 889

- ADC Conversion LED amb : 0x13 / 890 ; 0x14 / 1349

- PDN Cycle : 0x32 / 2149 ; 0x33 / 39199

I tested this timing and I did not see any issues.

Please let me know if you still encounter the issue of ADC_RDY pulses not getting generated.

0 Samuel Conti over 7 years ago in reply to Praveen Aroul

Intellectual 510 points

Hi,

It works fine , thank you very much!

Regards,

Sam

0 Praveen Aroul over 7 years ago in reply to Samuel Conti

TI__Mastermind 49176 points

Sam,

Thanks for letting me know.
Glad to help.

0 Simon Busch over 6 years ago in reply to Praveen Aroul

Prodigy 90 points

Hi,

I´m also trying to use the AFE4404 in 1-LED Mode. I copied the code above which works fine but I also want to change the LED. I tried to redo the code so I can use LED 2 or LED 3 but I do not get any satisfying data. The choosen LED turns on, but it seems like I messed up the detector or ADC time. Could you have a look and help me?

  AFE_Disable_Read();             //Beschreiben der Register ermöglichen

  if (befehl == 6)                //only green (LED 1)
  {
    AFE_Reg_Write(9, 0);        
    AFE_Reg_Write(1, 0);
    AFE_Reg_Write(10, 0);
    AFE_Reg_Write(2, 0);
    AFE_Reg_Write(21, 0);
    AFE_Reg_Write(22, 6);
    AFE_Reg_Write(13, 7);
    AFE_Reg_Write(14, 7);
    AFE_Reg_Write(54, 0);
    AFE_Reg_Write(55, 0);
    AFE_Reg_Write(5, 0);
    AFE_Reg_Write(6, 0);
    AFE_Reg_Write(23, 8);
    AFE_Reg_Write(24, 14);
    AFE_Reg_Write(15, 15);
    AFE_Reg_Write(16, 15);
    AFE_Reg_Write(3, 16);
    AFE_Reg_Write(4, 415);
    AFE_Reg_Write(7, 96);
    AFE_Reg_Write(8, 415);
    AFE_Reg_Write(25, 417);
    AFE_Reg_Write(26, 423);
    AFE_Reg_Write(17, 425);
    AFE_Reg_Write(18, 884);
    AFE_Reg_Write(11, 496);
    AFE_Reg_Write(12, 815);
    AFE_Reg_Write(27, 885);
    AFE_Reg_Write(28, 892);
    AFE_Reg_Write(19, 893);
    AFE_Reg_Write(20, 1352);

    farbe = 1;
  }else if (befehl == 7)                //only red (LED 3)
  {
    AFE_Reg_Write(9, 0);        
    AFE_Reg_Write(1, 0);
    AFE_Reg_Write(10, 0);
    AFE_Reg_Write(2, 0);
    AFE_Reg_Write(21, 0);
    AFE_Reg_Write(22, 6);
    AFE_Reg_Write(13, 7);
    AFE_Reg_Write(14, 7);
    AFE_Reg_Write(54, 8);
    AFE_Reg_Write(55, 407);
    AFE_Reg_Write(5, 87);
    AFE_Reg_Write(6, 407);
    AFE_Reg_Write(23, 408);
    AFE_Reg_Write(24, 424);
    AFE_Reg_Write(15, 426);
    AFE_Reg_Write(16, 885);
    AFE_Reg_Write(3, 0);
    AFE_Reg_Write(4, 0);
    AFE_Reg_Write(7, 0);
    AFE_Reg_Write(8, 0);
    AFE_Reg_Write(25, 886);
    AFE_Reg_Write(26, 892);
    AFE_Reg_Write(17, 893);
    AFE_Reg_Write(18, 893);
    AFE_Reg_Write(11, 0);
    AFE_Reg_Write(12, 0);
    AFE_Reg_Write(27, 894);
    AFE_Reg_Write(28, 900);
    AFE_Reg_Write(19, 0);
    AFE_Reg_Write(20, 0);

    farbe = 3;
  }else if (befehl == 8)                // only IR (LED 2)
  {
    AFE_Reg_Write(9, 0);        
    AFE_Reg_Write(1, 80);
    AFE_Reg_Write(10, 399);
    AFE_Reg_Write(2, 399);
    AFE_Reg_Write(21, 400);
    AFE_Reg_Write(22, 406);
    AFE_Reg_Write(13, 407);
    AFE_Reg_Write(14, 866);
    AFE_Reg_Write(54, 0);
    AFE_Reg_Write(55, 0);
    AFE_Reg_Write(5, 0);
    AFE_Reg_Write(6, 0);
    AFE_Reg_Write(23, 867);
    AFE_Reg_Write(24, 873);
    AFE_Reg_Write(15, 0);
    AFE_Reg_Write(16, 0);
    AFE_Reg_Write(3, 0);
    AFE_Reg_Write(4, 0);
    AFE_Reg_Write(7, 0);
    AFE_Reg_Write(8, 0);
    AFE_Reg_Write(25, 874);
    AFE_Reg_Write(26, 880);
    AFE_Reg_Write(17, 0);
    AFE_Reg_Write(18, 0);
    AFE_Reg_Write(11, 0);
    AFE_Reg_Write(12, 0);
    AFE_Reg_Write(27, 881);
    AFE_Reg_Write(28, 887);
    AFE_Reg_Write(19, 0);
    AFE_Reg_Write(20, 0);

    farbe = 2;
  }else if (befehl == 9)                //all LEDs 
  {  
    AFE_Reg_Write(1, 100);    //AFE_LED2STC
    AFE_Reg_Write(2, 399);    //AFE_LED2ENDC
    AFE_Reg_Write(3, 802);    //AFE_LED1LEDSTC
    AFE_Reg_Write(4, 1201);   //AFE_LED1LEDENDC
    AFE_Reg_Write(5, 501);    //AFE_ALED2STC
    AFE_Reg_Write(6, 800);    //AFE_ALED2ENDC
    AFE_Reg_Write(7, 902);    //AFE_LED1STC
    AFE_Reg_Write(8, 1201);   //AFE_LED1ENDC
    AFE_Reg_Write(9, 0);      //AFE_LED2LEDSTC
    AFE_Reg_Write(10, 399);   //AFE_LED2LEDENDC
    AFE_Reg_Write(11, 1303);  //AFE_ALED1STC
    AFE_Reg_Write(12, 1602);  //AFE_ALED1ENDC
    AFE_Reg_Write(13, 409);   //AFE_LED2CONVST
    AFE_Reg_Write(14, 1468);  //AFE_LED2CONVEND
    AFE_Reg_Write(15, 1478);  //AFE_ALED2CONVST
    AFE_Reg_Write(16, 2537);  //AFE_ALED2CONVEND
    AFE_Reg_Write(17, 2547);  //AFE_LED1CONVST
    AFE_Reg_Write(18, 3606);  //AFE_LED1CONVEND
    AFE_Reg_Write(19, 3616);  //AFE_ALED1CONVST
    AFE_Reg_Write(20, 4675);  //AFE_ALED1CONVEND
    AFE_Reg_Write(21, 401);   //AFE_ADCRSTSTCT0
    AFE_Reg_Write(22, 407);   //AFE_ADCRSTENDCT0
    AFE_Reg_Write(23, 1470);  //AFE_ADCRSTSTCT1
    AFE_Reg_Write(24, 1476);  //AFE_ADCRSTENDCT1
    AFE_Reg_Write(25, 2539);  //AFE_ADCRSTSTCT2
    AFE_Reg_Write(26, 2545);  //AFE_ADCRSTENDCT2
    AFE_Reg_Write(27, 3608);  //AFE_ADCRSTSTCT3
    AFE_Reg_Write(28, 3614);  //AFE_ADCRSTENDCT3
    AFE_Reg_Write(54, 401);   //AFE_LED3LEDSTC
    AFE_Reg_Write(55, 800);   //AFE_LED3LEDENDC

    farbe = 4;
  }
    
  // general settings

  AFE_Reg_Write(29, 39999);         //AFE_PRPCOUNT
  AFE_Reg_Write(30, 0x000103);      //Timer Engine aktivieren und NUMAV auf 4 Werte setzen
  AFE_Reg_Write(32, 0x008003);      //TIA Einstellungen: Seperate Gain = ON, LED2/LED3 Gain = 50K
  AFE_Reg_Write(33, 0x000003);       //TIA Einstellungen: LED1 Gain = 50K
  AFE_Reg_Write(58, 0x000000);      //Offset Einstellungen
  AFE_Reg_Write(34, 0x0063C5);      //Einstellen der LED Durchlassströme: Rot = 4,8 mA, Grün = 4 mA, IR = 5 mA
  AFE_Reg_Write(35, 0x124218);      //Internen Taktgeber und Dynamic Power Down aktivieren
  AFE_Reg_Write(41, 0x2);             //Verhindern, dass der interne Taktgeber nach außen übergeben wird
  AFE_Reg_Write(49, 0x000020);      //PD Einstellungen 
  AFE_Reg_Write(57, 0);             //CLKDIV_PRF
  AFE_Reg_Write(50, 5475);          //AFE Dynamic Power Down
  AFE_Reg_Write(51, 39199);         //AFE Dynamic Power On

0 Prabin Yadav over 6 years ago in reply to Simon Busch

TI__Genius 12555 points

Hi Simon,

As mentioned in the previous comments the ideal way to turn off the conversion phase is to give at-least 1 clock period. This ensures that the internal state machine works as expected. So can you please try the following setting for "befehl == 8".
AFE_Reg_Write(9, 0);
AFE_Reg_Write(1, 80);
AFE_Reg_Write(10, 399);
AFE_Reg_Write(2, 399);
AFE_Reg_Write(21, 400);
AFE_Reg_Write(22, 406);
AFE_Reg_Write(13, 407);
AFE_Reg_Write(14, 866);
AFE_Reg_Write(54, 1);
AFE_Reg_Write(55, 0);
AFE_Reg_Write(5, 1);
AFE_Reg_Write(6, 0);
AFE_Reg_Write(23, 867);
AFE_Reg_Write(24, 873);
AFE_Reg_Write(15, 874);
AFE_Reg_Write(16, 874);
AFE_Reg_Write(3, 1);
AFE_Reg_Write(4, 0);
AFE_Reg_Write(7, 1);
AFE_Reg_Write(8, 0);
AFE_Reg_Write(25, 875);
AFE_Reg_Write(26, 881);
AFE_Reg_Write(17, 882);
AFE_Reg_Write(18, 882);
AFE_Reg_Write(11, 1);
AFE_Reg_Write(12, 0);
AFE_Reg_Write(27, 882);
AFE_Reg_Write(28, 888);
AFE_Reg_Write(19, 889);
AFE_Reg_Write(20, 889);

Regards,
Prabin

0 Simon Busch over 6 years ago in reply to Prabin Yadav

Prodigy 90 points

Hi Prabin,

Thanks for your reply. I tested your suggestions butI still only get a constant value which is different every time I start the measurement.

Regards,

Simon

0 Prabin Yadav over 6 years ago in reply to Simon Busch

TI__Genius 12555 points

Hi Simon,

What NUMAV are you setting? Can you try lowering it?
Also can you change my suggestion as,

AFE_Reg_Write(27, 883);
AFE_Reg_Write(28, 889);
AFE_Reg_Write(19, 890);
AFE_Reg_Write(20, 890);

Regards,
Prabin

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AFE4404 in one LED Mode