TSL2571
LIGHT-TO-DIGITAL CONVERTER
TAOS117A − FEBRUARY 2011
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).
AIHTH(r 07), AIHTL(r 06)
APERS(r 0x0C, b3:0)
Upper Limit
CH0
ADC
CH0
Data
Lower Limit
CH0
AILTH(r 05), AILTL(r 04)
ALS Persistence
Figure 7. Programmable Interrupt
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