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5.1.6 DLP Spectrum Library
The DLP spectrum library is a collection of C-language routines that provide the fundamental pieces to
use a DLP system in a spectroscopy application. The DLP spectrum library is resolution and host
processor independent, allowing the routines to be used with different DMD resolutions and processor
systems. The routine sources are shared by the Tiva code, the GUI code, and the iOS App. The DLP
Spectrum Library are classified into three main categories:
•
Scan: Performing a column or Hadamard scan by:
– Generating the appropriate full-frame DMD patterns based on a specific scan configuration.
– Computing reflectance and absorbance data form the intensity data during a scan.
– Handling serialization and deserialization of scan configuration and scan data.
•
Calibration: Calibrating a system at the factory by:
– Finding peaks from a scan of a calibrated lamp.
– Finding the full width half maximum of specific peaks data of a calibration scan.
– Computing the calibration coefficients for a system.
•
Utilities: Utilities to handle:
– Conversion between DMD mirror column position to a calibrated wavelength or wave number, and
vice versa.
– Spectrum data calculations, such as: absorbance, reflectance, and spectrum comparisons.
– Matrix operations.
– Binary pattern packing.
The DLP NIRscan Nano utilizes a previously-created scan configuration (through the GUI or stored on the
NIRscan Nano) to perform a scan. This scan configuration is created on the NIRscanNanoGUI and
transferred to the system in serialized fashion. The system's Tiva processor deserializes this data and
generates a set of full-frame DMD patterns based on the scan configuration and the factory-stored
calibration data. Then, the Tiva turns on the lamps and streams the full-frame DMD patterns to perform a
scan. Tiva collects several data points for each pattern from the detector's ADC conversion. This data is
stored in a structure, and is then serialized and transferred to the PC through USB or Bluetooth. The
NIRscanNanoGUI or the iOS App deserializes this scan data, interprets it using the DLP Spectrum
Library, and plots the resulting spectrum.
5.1.7 DLP Spectrum Library Workflow
The following sections show the use of the DLP Spectrum Library workflow to read scan configuration
information, decode scan data, and compute reference, absorbance, and reflectance.
5.1.7.1
Scan Configuration Workflow
The DLP Spectrum Library routine to interpret scan configuration information is
dlpspec_scan_read_configuration(). This routine takes as input the serialized scan configuration
transferred through USB or Bluetooth and deserializes to extract all the scan configuration information.
Figure 5-2
shows the typical workflow to view configuration information. The white input box denotes USB
scan configuration data, while the blue input box denotes Bluetooth scan configuration data.
Configuration
Buffer Size
dlpspec_scan_read_configuration()
Configuration
Figure 5-2. DLP Spectrum Library View Configuration Information Workflow
DLPU030B – June 2015 – Revised July 2015
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Copyright © 2015, Texas Instruments Incorporated
Cast to scanConfig struct
DLP NIRscan Nano Software
Overview
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