TSL2571

LIGHT-TO-DIGITAL CONVERTER

TAOS117A − FEBRUARY 2011

9

The LUMENOLOGY

r Company

r

r

Copyright

E 2011, TAOS Inc.

www.taosinc.com

Interrupts

The interrupt feature simplifies and improves system efficiency by eliminating the need to poll the sensor for

light intensity values outside of a user-defined range. While the interrupt function is always enabled and it’s

status is available in the status register (0x13), the output of the interrupt state can be enabled using the ALS

interrupt enable (AIEN) field in the enable register (0x00).

Two 16-bit interrupt threshold registers allow the user to set limits below and above a desired light level range.

An interrupt can be generated when the ALS CH0 data (C0DATA) falls outside of the desired light level

range, as determined by the values in the ALS interrupt low threshold registers (AILTx) and ALS interrupt high

threshold registers (AIHTx). It is important to note that the low threshold value must be less than the high

threshold value for proper operation.

To further control when an interrupt occurs, the device provides a persistence filter. The persistence filter allows

the user to specify the number of consecutive out-of-range ALS occurrences before an interrupt is generated.

The persistence register (0x0C) allows the user to set the ALS persistence (APERS) value. See the persistence

register for details on the persistence filter values. Once the persistence filter generates an interrupt, it will

continue until a special function interrupt clear command is received (see command register).

CH0

ADC

CH0

Data

CH0

Upper Limit

Lower Limit

AIHTH(r 07), AIHTL(r 06)

ALS Persistence

AILTH(r 05), AILTL(r 04)

APERS(r 0x0C, b3:0)

Figure 7. Programmable Interrupt