QRE1113 Analog Sensors Generating Unpredictable Numbers

Other Hardware General Electronics
1

Hello Everyone,
I have 3 sparkfun qre1113 sensors which are analog. I am trying to make a maze solver that utilizes all three sensors but all three are reporting big gaps between numbers.

Sensors Are Hooked Up To Separet Battery For Power. They Are Connected on pins A0, A1, and A2.

Heres My Debugging Code

void setup(){
  pinMode(A0, INPUT);
  pinMode(A1, INPUT);
  pinMode(A2, INPUT);
  Serial.begin(9600);
}

void loop(){
  
Serial.println(analogRead(A0));
Serial.println(analogRead(A1));
Serial.println(analogRead(A2));
Serial.println("_____________");
delay(1000);
}

Here Is Serial Output(I Put them in code brackets because there is so many numbers)

539
842
585
_____________
606
845
634
_____________
664
846
682
_____________
592
842
620
_____________
556
844
599
_____________
673
845
685
_____________
582
843
619
_____________
538
845
582
_____________
616
843
639
_____________
631
843
652
_____________
537
845
586
_____________
556
842
598
_____________
627
843
649
_____________
550
846
592
_____________
547
842
587
_____________
537
843
583
_____________
568
844
603
_____________
653
842
670
_____________
643
843
660
_____________
552
846
599
_____________
545
841
584
_____________
659
842
675
_____________
520
844
569
_____________
549
840
593
_____________
580
843
614
_____________
541
843
583
_____________
566
840
600
_____________
529
843
578
_____________
634
842
655
_____________
543
841
588
_____________
487
843
544
_____________
516
841
563
_____________
538
840
579
_____________
575
843
614
_____________
578
841
614
_____________
596
841
626
_____________
729
843
727
_____________
599
840
626
_____________
438
841
507
_____________
661
843
677
_____________
630
840
650
_____________
716
841
715
_____________
517
842
572
_____________
704
838
704
_____________
522
840
570
_____________
584
842
613
_____________
526
838
575
_____________
532
841
573
_____________
632
841
651
_____________
533
838
575
_____________
582
841
616
_____________
619
839
642
_____________
578
838
611
_____________
538
841
580
_____________
592
839
619
_____________
777
840
761
_____________
721
843
717
_____________
676
839
686
_____________
663
841
675
_____________
607
841
632
_____________
604
839
629
_____________
614
842
641
_____________
609
839
636
_____________
619
840
642
_____________
636
843
661
_____________
606
839
631
_____________
Above When Off A Line

Below On A Line

652
1009
739
_____________
626
1009
716
_____________
609
1009
697
_____________
591
1009
689
_____________
599
1009
699
_____________
636
1009
729
_____________
652
1009
736
_____________
656
1009
733
_____________
624
1009
712
_____________
610
1009
705
_____________
647
1009
739
_____________
760
1009
817
_____________
709
1009
775
_____________
658
1009
736
_____________
778
1009
831
_____________
556
1009
667
_____________
597
1009
695
_____________
605
1010
703
_____________
619
1009
708
_____________
614
1009
705
_____________

Thank You SO Much!

2

You have commoned the ground together of course?

3

At the time the arduino was powered by the computer and the sensors by battery. How do I common the grounds together and read serial output?

Thank You So Much
Jordan

4

Hi, all three negative terminals of your sensor supplies must be connected together and then connected to the gnd pin on the arduino.

Without the grounds connected, the arduino analog inputs have no reference point.

Tom..... :slight_smile:

5

Voltage is also called "potential difference" - a difference can only be measured between two signals. Without the grounds connected each circuit is using the other as a radio antenna.