Porting this code

[sreibs]

Hi guys,

I am trying to use this with a raspberry. I used this code and the BCM2835 for hardware management (GPIO etc....).

Most is working (communication, SPI, spo² value seems correct..) but the heartbeat is very unstable (78bpm then 150 then 90...).

Can you point at extra care to have to get this code working on another target? I have seen the "FS" constant that is supposed to be a sampling frequency, but I don't know how to adjust it for my target.

Thank you very much for your help.

[protocentralashwin]

@sreibs It looks you might be missing samples, can you please recheck your readback routines (to read data from the AFE4490's SPI)?

[adelalfusail]

its not stable except when there is no light in the room

[sreibs]

Hi all, I am sorry for being so late, this topic has been putting aside for a (too) long time. Here is the routine:

bool processAFE44xxMeasure(void){
    bool result = false;

//  if (drdy_trigger == HIGH)
    if(bcm2835_gpio_lev(PIN_DRDY) == HIGH)
     {
//        detachInterrupt(0);
        afe44xxWrite(CONTROL0,0x000001);  
        IRtemp = afe44xxRead(LED1VAL);
        afe44xxWrite(CONTROL0,0x000001);  
        REDtemp = afe44xxRead(LED2VAL);   
        afe44xx_data_ready = true;
     }  

    if(afe44xx_data_ready == true)
    {

        IRtemp = (unsigned long) (IRtemp<<10);
        seegtemp = (signed long) (IRtemp);
        seegtemp = (signed long) (seegtemp>>10);  

        REDtemp = (unsigned long) (REDtemp<<10);
        seegtemp2 = (signed long) (REDtemp);
        seegtemp2 = (signed long) (seegtemp2>>10);

        if(dec==20)
        {
          aun_ir_buffer[n_buffer_count]=(uint16_t) (seegtemp>>4);
          aun_red_buffer[n_buffer_count]=(uint16_t) (seegtemp2>>4);
          n_buffer_count++;
          dec=0;

        }
        dec++;

        if(n_buffer_count>99)
        {

          estimate_spo2(aun_ir_buffer, 100, aun_red_buffer, &n_spo2, &ch_spo2_valid,&n_heart_rate, &ch_hr_valid); 
          g_AFE44xxData.bpm = (float)n_heart_rate;
          g_AFE44xxData.spo2 = (float)n_spo2;
          printf("Estimate data : \tbpm:%.0f\tspo2:%0.1f\n", g_AFE44xxData.bpm, g_AFE44xxData.spo2);
          fflush(stdout);
          n_buffer_count=0;
          if(g_AFE44xxData.bpm >= 0 && g_AFE44xxData.spo2 >= 0){
              result = true;
            }
        }         

        afe44xx_data_ready = false;
        drdy_trigger = LOW;
//      attachInterrupt(0, afe44xx_drdy_event, RISING );  
        while(bcm2835_gpio_lev(PIN_DRDY) == HIGH);

    }        
    return result;
}

Do you think it is a matter of light in the room ?

Thank you for your feedback,