MSP-EXP432P401R LaunchPad and TSL2561 light-to-digital converter

In this example we show how to connect a TSL2561 is a light-to-digital converter to a MSP-EXP432P401R LaunchPad, the example will use the Energia IDE.

I used a TSL2561 module in this example, which you can see below

The TSL2561 is a light-to-digital converter that transforms light intensity to a digital signal output capable of an I²C interface. Each device combines one broadband photodiode (visible plus infrared) and one infrared-responding photodiode on a single CMOS integrated circuit capable of providing a near-photopic response over an effective 20-bit dynamic range (16-bit resolution).

Two integrating ADCs convert the photodiode currents to a digital output that represents the irradiance measured on each channel. This digital output can be input to a microprocessor where illuminance (ambient light level) in lux is derived using an empirical formula to approximate the human eye response. The TSL2561 device supports a traditional level style interrupt that remains asserted until the firmware clears it.

More info – http://ams.com/eng/Products/Light-Sensors/Ambient-Light-Sensors/TSL2561

Connection

Here is a picture of the launchpad so you can see what pins we are referring to below in the table

launchpad pins1

Code

[codesyntax lang=”cpp”]

#include<Wire.h>

// TSL2561 I2C address is 0x39(57)
#define Addr 0x39

void setup()
{
  // Initialise I2C communication as MASTER 
  Wire.begin();
  // Initialise serial communication, set baud rate = 9600
  Serial.begin(9600);

  // Starts I2C communication
  Wire.beginTransmission(Addr);
  // Select control register
  Wire.write(0x00 | 0x80);
  // Power ON mode
  Wire.write(0x03);
  // Stop I2C Transmission
  Wire.endTransmission();

  // Starts I2C communication
  Wire.beginTransmission(Addr);
  // Select timing register
  Wire.write(0x01 | 0x80);
  // Nominal integration time = 402ms
  Wire.write(0x02);
  // Stop I2C Transmission
  Wire.endTransmission();
  delay(300);
  
}

void loop()
{ 
  unsigned int data[4];
  for(int i = 0; i < 4; i++)
  {
    // Starts I2C communication
    Wire.beginTransmission(Addr);
    // Select data register
    Wire.write((140 + i));
    // Stop I2C Transmission
    Wire.endTransmission();
    
    // Request 1 byte of data
    Wire.requestFrom(Addr, 1);
    
    // Read 1 bytes of data
    if(Wire.available() == 1)
    {
      data[i] = Wire.read();
     }
     delay(200);
  }
  
  // Convert the data
  double ch0 = ((data[1] & 0xFF) * 256) + (data[0] & 0xFF);
  double ch1 = ((data[3] & 0xFF) * 256) + (data[2] & 0xFF);

  // Output data to serial monitor
  Serial.print("Full Spectrum(IR + Visible) :");
  Serial.println(ch0);
  Serial.print("Infrared Value :");
  Serial.println(ch1);
  Serial.print("Visible Value :");
  Serial.println(ch0-ch1);
}

[/codesyntax]

Output

Open the serial monitor and you should see something like this

Full Spectrum(IR + Visible) :184.00
Infrared Value :25.00
Visible Value :159.00
Full Spectrum(IR + Visible) :176.00
Infrared Value :12.00
Visible Value :164.00
Full Spectrum(IR + Visible) :8.00
Infrared Value :2.00
Visible Value :6.00
Full Spectrum(IR + Visible) :8.00
Infrared Value :11.00
Visible Value :-3.00
Full Spectrum(IR + Visible) :141.00
Infrared Value :22.00
Visible Value :119.00

Links

1pcs GY-2561 TSL2561 Luminosity Sensor Breakout infrared Light Sensor module integrating sensor AL