Getting IS471F to work

Other Hardware Sensors
1

Hi everyone,

I am building an installation with a light barrier which can detect when people walk through a certain area. I am using a Sharp IS471F to detect light off an infra-red LED but I can't figure out how to make it work. I think this is more a wiring / hardware problem as I just can't get the sensor to read any values. Please find the attached setup.

As from what I understand I connected to 1: 5V, 2: Signal to Arduino, 3: GND, 4: To LED - but somehow it does not give me any input signals. I assume the IR-LED is working as it lights up when I use a regular LED. I use a condensator which has a higher value than suggested in the data sheet, but basically it should work without a condensator as well, right?

Here is the code I am using to test the signal:

int irinput = 6;    
int valir = 0;

void setup() {
 Serial.begin(9600);
 pinMode(irinput, INPUT);   
}
    
void loop(){
  valir = digitalRead(irinput);
  Serial.print("state = ");
  Serial.println(valir);
  delay(1000);
}

Data sheet of the IS471F: HTTP 301 This page has been moved

Any ideas what I am doing wrong? Any suggestions would be appreciated very much.

is471f.jpg
is471f.jpg1200×900 223 KB

2

What about the resistor 280 Ohm, shown on Fig. 4?

3

thanks for the hint magician. i forgot about this one. but then it also made me try it as an analogue read... and it worked. at least with a normal red led. so i think it might have been an issue of reflection and the led being too close for it to be true digital signal. will investigate further.