8.3.3 Interrupt Operation, INT Pin, and Interrupt Reporting Mechanisms

The device has an interrupt reporting system that allows the processor connected to the I²C bus to go to sleep, or otherwise ignore the device results, until a user-defined event occurs that requires possible action. Alternatively, this same mechanism can also be used with any system that can take advantage of a single digital signal that indicates whether the light is above or below levels of interest.

The interrupt event conditions are controlled by the high-limit and low-limit registers, as well as the configuration register latch and fault count fields. The results of comparing the result register with the high-limit register and low-limit register are referred to as fault events. The fault count register dictates how many consecutive same-result fault events are required to trigger an interrupt event and subsequently change the state of the interrupt reporting mechanisms, which are the INT pin, the flag high field, and the flag low field. The latch field allows a choice between a latched window-style comparison and a transparent hysteresis-style comparison.

The INT pin has an open-drain output, which requires the use of a pull-up resistor. This open-drain output allows multiple devices with open-drain INT pins to be connected to the same line, thus creating a logical NOR or AND function between the devices. The polarity of the INT pin can be controlled with the polarity of interrupt field in the configuration register. When the POL field is set to 0, the pin operates in an active low behavior that pulls the pin low when the INT pin becomes active. When the POL field is set to 1, the pin operates in an active high behavior and becomes high impedance, thus allowing the pin to go high when the INT pin becomes active.

Additional details of the interrupt reporting registers are described in the Interrupt Reporting Mechanism Modes and Internal Registers sections.