Light to Frequency help

Forum 2005-2010 (read only) Hardware Interfacing
#1

Hey everyone, I recently purchased a TSL230 from sparkfun As I understand it, this little guy outputs a square wave with a frequency that is influenced by the intensity of light. Looking around at previous posts I found this code

long pulseTime;
#define pulsePin  3    // change this to input pin
#define TSL_S0       5  
#define TSL_S1       6  
#define TSL_S2       7  
#define TSL_S3       8 

void setup(){
Serial.begin(9600);

#  pinMode(TSL_S0, OUTPUT);  
#  pinMode(TSL_S1, OUTPUT);  
#  pinMode(TSL_S2, OUTPUT);  
#  pinMode(TSL_S3, OUTPUT);  
#   
#  digitalWrite(TSL_S0, HIGH);  
#  digitalWrite(TSL_S1, LOW);  
#  digitalWrite(TSL_S2, HIGH);  
#  digitalWrite(TSL_S3, HIGH);


}


void loop(){
// first two lines prevent reading an incomplete pulse
pulseTime=0;                                     // clean out variable
while(digitalRead(pulsePin) == 1){};   // find a high pulse
while(digitalRead(pulsePin) == 0){};   // find a low pulse
while(digitalRead(pulsePin) == 1){       // we know we are at the beginning of a clean pulse now
pulseTime++;
}

Serial.println(pulseTime);     // debug variable

}

I'm not getting anything values sent back when I run this, it acts as if the arduino does not see any high/low pulses. It should send me some sign that the arduino is reading each pulse

if I try printing out the digitalRead value of the input pin, I get nothing but 0 if I try printing out the analogRead of the input pin, I see 0 and 1000, so I know there is some input coming from sensor. Isn't the 0 - 1000 a pulse, on/off?

I'm unfamiliar with how this is supposed to work, so forgive me ignorance.

The goal is to have the sensor see a bright object on my LCD TV screen and trigger an action through the arduino, I chose this chip because I'm hoping it will get me a very clean absolute input so I don't have to burden the Arduino with averaging out and cleaning up an analog signal.

thanks for the help

-joe

p.s. I have the chip wired up as instructed in this tutorial http://roamingdrone.wordpress.com/2008/11/13/arduino-and-the-taos-tsl230r-light-sensor-getting-started/

#2

hmm, you probably have something wrong with your circuit. the code looks short and fine. wiggle the wires around and see if anything changes

#3

I double checked, everything is plugged in right.

I printed out an analogRead of the input pin, it is still shifting between 0 and 1024 with nothing in between, which is what I think is what a pulse would look like, if I shine a bright light on it, the numbers range from 300-500 with a lot of inbetween numbers, so I know that the sensor is sending data to the arduino, the question is how to use that data.

If I print a digitalRead I get nothing but 0’s still.

I would think that a 1000 would read as high, and 0 as low.
I’ve read that the light should influence the frequency, with is the distance between low and high, but I can’t even get a reading of low and high.

am I making false assumptions on how this thing works?

Does that sound like a problem with the chip still? or maybe the Arduino? the code?

Im using an Arduino Mega if that makes any difference.

thanks again for the assistance!

-joe

#4

Problem solved, because I was using Arduino MEGA, the
#define TSL_S0 5
#define TSL_S1 6
#define TSL_S2 7
#define TSL_S3 8
where actually Analog Inputs

I hooked it up to a Duemilanove and it appears to be working now.

-joe

#5