TSL2771

LIGHT-TO-DIGITAL CONVERTER

with PROXIMITY SENSING

TAOS100B − FEBRUARY 2011

12

r

r

Copyright

E 2011, TAOS Inc.

The LUMENOLOGY

r Company

www.taosinc.com

Interrupts

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

light intensity or proximity 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 proximity interrupt enable (PIEN) or ALS interrupt enable (AIEN) fields in the enable register (0x00).

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

proximity 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). Likewise, an out-of-range proximity interrupt can be generated when

the proximity data (PDATA) falls below the proximity interrupt low threshold (PILTx) or exceeds the proximity

interrupt high threshold (PIHTx). 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 or proximity occurrences before an interrupt

is generated. The persistence register (0x0C) allows the user to set the ALS persistence (APERS) and the

proximity persistence (PPERS) values. 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).

Prox

ADC

Prox

Data

CH0

ADC

CH0

Data

Prox

Integration

CH0

CH1

Upper Limit

Upper Limit

Lower Limit

Lower Limit

Prox Persistence

PILTH(r 09), PILTL(r 08)

AIHTH(r 07), AIHTL(r 06)

ALS Persistence

AILTH(r 05), AILTL(r 04)

PIHTH(r 0x0B), PIHTL(r 0x0A)

PPERS(r 0x0C, b7:4)

APERS(r 0x0C, b3:0)

Figure 12. Programmable Interrupt