Datasheet

The library is fairly simple to use. The first line of code in the example is the 'constructor' where you

can supply the I2C ADDR (in case you want to change it), and a unique ID to attach to this sensor

(you can just leave this to the default value of 12345 for now). By modifying the I2C address we can

have up to three TSL2561 sensors connected on the same board:

// The address will be different depending on whether you leave

// the ADDR pin float (addr 0x39), or tie it to ground or vcc. In those cases

// use TSL2561_ADDR_LOW (0x29) or TSL2561_ADDR_HIGH (0x49) respectively

Adafruit_TSL2561 tsl = Adafruit_TSL2561(TSL2561_ADDR_FLOAT, 12345);