TSL2561 sensor and LPC1768 example

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.

Parts List

Label Part Type
MBED1 mbed LPC1768
Part2 Adafruit TSL2561



mbed and TSL2561
mbed and TSL2561


The following example uses the MBed online compiler and is imported from https://os.mbed.com/components/Grove-Digital-Light-Sensor/

#include "mbed.h"
#include "TSL2561.h"
#define PC_PRINTX(z,x)             if(z==1) PC.printf(x);
#define PC_PRINTLNX(z,x)           if(z==1) {PC.printf(x);        PC.printf("\r\n");}
#define PC_PRINTXY(z,x, y)         if(z==1) PC.printf(x, y);
#define PC_PRINTLNXY(z,x, y)       if(z==1) {PC.printf(x, y);     PC.printf("\r\n");}
DigitalOut myled(LED1);
TSL2561 tsl2561(TSL2561_ADDR_FLOAT);
Timer setuptimer;
Timer executetimer;
void setup(void){
    if (tsl2561.begin()) {    
        PC_PRINTLNX(1,"TSL2561 Sensor Found");        
    } else {    
        PC_PRINTLNX(1,"TSL2561 Sensor not Found");   
    // You can change the gain on the fly, to adapt to brighter/dimmer tsl2561 situations
  tsl2561.setGain(TSL2561_GAIN_0X);         // set no gain (for bright situtations)
  //tsl2561.setGain(TSL2561_GAIN_16X);      // set 16x gain (for dim situations)
  // Changing the integration time gives you a longer time over which to sense tsl2561
  // longer timelines are slower, but are good in very low tsl2561 situtations!
  //tsl2561.setTiming(TSL2561_INTEGRATIONTIME_13MS);  // shortest integration time (bright tsl2561)
  //tsl2561.setTiming(TSL2561_INTEGRATIONTIME_101MS);  // medium integration time (medium tsl2561)
  tsl2561.setTiming(TSL2561_INTEGRATIONTIME_402MS);  // longest integration time (dim tsl2561)
  // Now we're ready to get readings!
int main() {  
    PC_PRINTLNXY(1,"Setup time: %f",setuptimer.read());
    uint16_t x,y,z;
    while(1) {      
        // Simple data read example. Just read the infrared, fullspecrtrum diode 
        // or 'visible' (difference between the two) channels.
        // This can take 13-402 milliseconds! Uncomment whichever of the following you want to read
        x = tsl2561.getLuminosity(TSL2561_VISIBLE);     
        y = tsl2561.getLuminosity(TSL2561_FULLSPECTRUM);
        z = tsl2561.getLuminosity(TSL2561_INFRARED);
        PC_PRINTLNXY(1,"Visible: %d",x);
        PC_PRINTLNXY(1,"Full Spectrum: %d",y);
        PC_PRINTLNXY(1,"Infrared: %d",z);
        PC_PRINTLNXY(1,"Execution Time: %f",executetimer.read());
        //More advanced data read example. Read 32 bits with top 16 bits IR, bottom 16 bits full spectrum
        //That way you can do whatever math and comparisons you want!
         // uint32_t lum = tsl2561.getFullLuminosity();
       // uint16_t ir, full;
      //  ir = lum >> 16;
      //  full = lum & 0xFFFF;
     //   PC_PRINTLNXY(1,"Visible: %d",full - ir);
     //   PC_PRINTLNXY(1,"Full Spectrum: %d",full);
     //   PC_PRINTLNXY(1,"Infrared: %d",ir);  
    //    wait(1);


Using a terminal program such as Teraterm you should see something like

Visible: 372
Full Spectrum: 1764
Infrared: 2116
Execution Time: 1.213755
Visible: 3818
Full Spectrum: 9853
Infrared: 2750
Execution Time: 1.213749
Visible: 38
Full Spectrum: 221
Infrared: 164
Execution Time: 1.213792
Visible: 46
Full Spectrum: 212
Infrared: 165
Execution Time: 1.213857


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