MSP430FR4133 LaunchPad and TSL2561 Sensor example using Energia

In this article we take a look at the TSL2561 and connect it to a MSP430FR4133 LaunchPad

This TSL2561 is an I2C light-to-digital converter TSL2561 that transforms light intensity to a digital signal. The TSL2561 features a selectable light spectrum range due to its dual light sensitive diodes: infrared and full spectrum. You can switch among three detection modes to take your readings. They are infrared mode, full spectrum and human visible mode.

When running under the human visible mode, this sensor will give you readings just close to your eye feelings.

Features

Selectable detection modes
High resolution 16-Bit digital output at 400 kHz I2C Fast-Mode
Wide dynamic range: 0.1 – 40,000 LUX
Wide operating temperature range: -40°C to 85°C
Programmable interrupt function with User-Defined Upper and lower threshold settings

Here is a typical module that makes it easier to work with the sensor

Parts Required

Schematic/Connection

Here are the connectors on the launchpad

Code Example

[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]

Testing

Open the serial monitor window, mover the sensor to light sources, cover the sensor. you can see in the example below me moving to a bright light source and the value increasing

Full Spectrum(IR + Visible) :858.00
Infrared Value :525.00
Visible Value :333.00
Full Spectrum(IR + Visible) :464.00
Infrared Value :60.00
Visible Value :404.00
Full Spectrum(IR + Visible) :42.00
Infrared Value :32.00
Visible Value :10.00