TSL2540 EVM User Guide
Page 8
4.7
“ALS” Tab
The main portion of the screen contains a tab labeled ALS. The controls in this tab are divided into 3
sections, each performing a separate function.
Figure 9. ALS Tab
4.7.1 ALS Controls
The left side of the ALS tab contains controls to set various ALS settings.
The
ATIME
control sets the time of the ALS integration. ATIME can be adjusted in 2.778ms steps.
The
AGAIN
control is a pulldown menu which sets the analog gain of the ALS sensor. The values
available are 1/2x, 1x, 4x, 16x, 64x, and 128x.
The
WEN
checkbox controls the ALS Wait feature. When this box is checked, the values for
WTIME and WLONG are used to determine the time between ALS cycles. When this box is
unchecked, there is no wait period between ALS cycles and the values of WTIME and WLONG are
ignored.
The
WTIME
control sets the time to wait between ALS cycles. WTIME can be adjusted in 2.778ms
steps.
The
WLONG
checkbox controls sets the WTIME factor. When this box is checked, the wait time
between ALS cycles is extended by a factor of 12x.
4.7.2 ALS Lux Coefficients
The TSL2540 ALS supplies information that is used to calculate Lux (unit of illumination). The Lux
equation for the TSL2540 uses a combination of data from the sensor and various coefficients to
calculate the Lux value. The software is pre-configured with coefficients for an open-air
configuration. When the sensor is placed behind glass, different coefficients should be loaded into
the software to update the Lux equation. The coefficients can be loaded or saved to an XML file
using the File menu. To ensure the proper XML format first save the current coefficients using
File
>
Lux Coefficients
>
Save
. Once the file is saved located the XML file created and edit with a text
