TAOS TCS3471 Light-To-Digital Color Light Sensor Evaluation System User Guide

TAOS TCS3471 Light-To-Digital Color Light Sensor Evaluation System

Product Information

• Product Name: TCS3471 EVM
• Revision: 3.1
• User’s Guide: TCS3471 LIGHT-TO-DIGITAL COLOR LIGHT SENSOR EVALUATION SYSTEM
• Date: August 2011

Product Usage Instructions

Initial Hardware Setup:

1. Install the software before connecting any hardware to the computer. Refer to the Quick Start Guide (QSG) for instructions.
2. The hardware required for setup includes the Controller EVM v2.1 motherboard, the TCS3471 evaluation daughterboard, and a USB interface cable.
3. Connect the USB cable to the computer. The green LED should light up, indicating power is being received via the USB interface and the controller board processor is running.
4. If the green LED does not light up, check the USB cable connections. Unplug the USB cable and try again.
5. If there is still no green LED after re-trying, check the PC for USB error messages. For additional assistance, refer to the resources section at the end of the user manual.

Establishing Basic Functionality:

1. To start the software, either use the desktop icon “TAOS
   • DigitalLightSensor v4_20″ or double click on the “TAOS
   • DigitalLightSensor v4.20.exe” file from the installation directory.
2. The default installation directory path is:
   • C: Program FilesTAOSTCS3x71EVM (for Windows 32-bit operating systems)
   • C: Program Files (x86)TAOSTCS3x71EVM (for Windows 64-bit operating systems)
3. After starting the software, two windows will open on the PC. The bottom window is the main user interface child window and should be positioned on the screen for easy access. The top window, which is the parent window, is not typically needed and may be placed out of the way. The parent window can be used to reset the child window if necessary.

Additional Resources:

For customer support in various technical areas, Texas Advanced Optoelectronic Solutions (TAOS) provides assistance. However, TAOS assumes no responsibility for customer product design or the use or application of customers’ products, nor for any infringements of patents or rights of others that may result from TAOS’ assistance.

For more information, visit www.taosinc.com.

INITIAL HARDWARE SETUP

The software should be installed prior to connecting any hardware to the computer. Follow the instructions found in the Quick Start Guide (QSG). This will load the required driver for the USB interface and also the graphical user interface (GUI).
The hardware consists of the Controller EVM v2.1 motherboard, the TCS3471 evaluation daughterboard and a USB interface cable.

When the USB cable is connected the green LED should light up indicating that power is being received via the USB interface, and the controller board processor is running. If the green LED does not light up check the USB cable connections unplug the USB cable and try again. If after re-try no green LED check the PC for USB error messages. See resources section at end of this document for additional assistance.

ESTABLISHING BASIC FUNCTIONALITY

The software should be started using the desktop icon “TAOS DigitalLightSensor v4_20” or by double clicking the “TAOS DigitalLightSensor v4.20.exe” file from the installation directory. The default installation directory path is:

• C:\Program Files\TAOS\TCS3x71EVM Windows 32 bit operating systems
• C:\Program Files (x86)\TAOS\TCS3x71EVM Windows 64 bit operating systems

Although a different install path may be selected by the user. When started, the following windows will open on the PC. The bottom window is the main user interface “child window” and should be positioned on the screen for easy access. The top window “parent window” is not typically needed and may be placed out of the way. This window is the parent window (PW) to the child window (CW) and may be used to reset the CW.

Clicking on the red “X” on the PW will close both PW and CW. Clicking on the red “X” on the CW will close only the CW. The “Functional” tabs on both the left and right side of the CW will be selected by default each time the application software is opened On the right side numbers should be changing showing that the ALS and proximity functions are operational. By changing the ambient light source or waving your hand over the sensor at ~4 inch (100mm) separation you should see the ALS and proximity readings change correspondingly with light level reaching the sensor.

The balance of this document identifies and describes the controls available on the different tabs of the GUI. In combination with the TCS3471 datasheet, the quick start guide (QSG) and application notes available on the TAOS website www.TAOSinc.com there should be enough information to allow thorough evaluation of the TCS3471 device.

SOFTWARE OVERVIEW

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• This window has inputs organized on the left, and outputs organized on the right. Values for regi variables may be set using multiple techniques. The Functional tab is commonly used to quickly evaluate the device with nominal settings. The Input Register tab allows the register settings to be changed, and the Output Register tab allows registers to be viewed. Other tabs provide additional demonstration and test features for evaluation.

By default the “Functional” tabs have the focus. The values shown in this document will not exac match a users system but the basic window and controls should be identical. This document will identify the usage and operation of these items in detail.

Always visible along the bottom are the following controls:

• LED Off – ON/OFF/ON toggle for the green controller board LED. This LED is a good power-on indicator but can introduce errors in the optical tests. However it is recommended for accurate measurements to turn the LED off.

• A section containing logging controls and sampling status information:

  1. Toggles LED on the controller board.

  2. Text entered here is appended to the default file name. The file name contains the Part Name and address shown in the large “Child” window, an underscore “_” and the text entered. The default if nothing is entered is a period(“.”).

  3. Secondary comment box. Text entered here is also appended to the log file name. . The default if nothing is entered is a period(“.”).
     Sample :

  4. The start button tells the program to start logging. The fields entered in #2 and #3 will be used as field names in the output. If you change the values in #2 or #3, the corresponding field names will change in the output beginning at the time of the change, but the log file name will not change after logging is started.

  5. Clear –The Clear button will flush the previous optical sample readings and reset the elapsed time indicator (see #7).

  6. Log – Creates a text log file with data. The name will be assigned as explained in #3. This will cause the system to write out any data currently in the log buffer.

  7. Count of samples in the log buffer. When that number reaches the limit selected in #9, the system will show a file dialog to save the log in a named file.

  8. The elapsed time since the beginning of logging data.

  9. The number of log samples to collect before log entry is written to the log file.

INPUT SIDE, “FUNCTIONAL” TAB

Simple commonly used controls exist for the ALS functionality, the proximity detection functionality, the wait time between samples, and the proximity threshold level.

ALS SENSOR

• Gain – The gain control allows the user access to the AGAIN settings in the Control Register (0x0F). The gain amplifies the ADC signal to increase sensitivity. The gain options include 1x, 4x, 16x and 60x and are selected from the list box when the down arrow is depressed.
• Time (mS) – This list box has numerous preselected values for the integration time of all channels (Red, Blue, Green and Clear). If a value other than what is shown in the list box is desired it must be entered manually using the Register tab (documented later). Manually entering a value will NOT work in this location. The actual integration time is shown on the line below.
  • NOTE : The saturation level of the device is partially dependant on the integration time. Digital saturation occurs when the ADC output registers overflow. Digital saturation is reached at 65,536, thus the full-scale output of the TCS3471 is 65,535 (16-bits). If the integration time is set less than 172ms, however, the dynamic range of the device will be limited to the following: Integration Time > 172ms Saturation = 65,535 Integration Time < 172ms Saturation = ((Integration Time / 2.4) x 1024) – 1

WAIT TIME

When the software initializes, a default wait period of 2.4mS is inserted between the Prox execution and the ALS execution. This duration can be adjusted in 2.4mS steps from 0 to 614mS. A wait multiplier (WLONG=1) may also be used to multiply the wait period by 12x. Using these controls the duration of the wait may be adjusted from none (WEN=0) to 7.37 seconds (WEN=1, WLONG=1, WTIME=0x00).

The Wait Time list box provides a quick mechanism for setting preselected wait periods from 2.4mS to 614mS. The wait period is completely disabled by setting WEN=0 (Enable Register (0x00, bit3).

INPUT SIDE, “REGISTER” TAB

“Control” Sub Tab

The Register tab provides for direct control of the registers of the device.

The Control sub-tab allows enabling and disabling functionality in the part and also controls the wait time multiplier (WLONG).

Additionally, a list box provides options for turning ON all parts (All On) of the device or turning OFF all parts (All Off) of the device simultaneously.

• Enable Register (0x00) – Provides the ON/OFF control of the device.
• Check boxes are provided to allow selection of specific functions on the device:
  1. PON – Power on. Activates internal oscillator. When =0 device is in standby.
  2. AEN – ALS Enable. Writing a one (1) enables the ALS
  3. WEN – Wait Enable. Writing a one (1) activates the wait timer.
  4. AIEN – ALS Interrupt Enable. Writing a one (1) enables the ALS interrupt.
• WTIME (0x03) – Wait time in 2.4ms increments, unless the WLONG bit is set, in which case the wait time is multiplied by 12. The number to the right is the computed WTIME. See the ATIME note in the ALS Sub Tab description.
• Config Register (0x0D) – Controls the wait time multiplication factor of x12.
  1. WLONG – Wait Long. When checked (=1) enables the wait multiplier.

“ALS” Sub Tab

The ALS tab shows the registers associated with ambient light sensing control. Register values in hex are shown on the left, preselected values are available in list boxes in the middle, and actual values are shown on the right.

box value or clear the value from the list box so the screen is correct.

Note :
The column on the right is the computed value for ATIME and is always correct. Sometimes the value shown in the list box will be one of the preselected values but it has not been selected. If this happens the number will not be the same as the computed number for WTIME on the Control Sub-Tab. The computed value is the one that is correct. This can be fixed by selecting a preselected value from the list box or by cycling the register value UP/DOWN or DOWN/UP. This will set the list

“ALS Interrupt” Sub Tab

This tab contains the settings for controlling the generation of ALS interrupts to a control processor.

The AILT and AIHT values are 16 bit thresholds for the upper and lower trigger points. Each is set using two 8-bit registers. Another control (APERS) establishes the required persistence of the interrupt signal.

Also on this screen is a control that will automatically generate the register values to provide threshold settings 25% higher and lower than the currently measured amount of ambient

Light:

• ALS Interrupt Low Threshold (0x04, 0x05) – Low light threshold for ALS interrupt.
  1. AILTL (0x04) – The lower 8 bits of the 16 bit low threshold value.
  2. AILTH (0x05) – The upper 8 bits of the 16 bit low threshold value.
• ALS Interrupt High Threshold (0x06, 0x07) – High light threshold for ALS interrupt.
  1. AIHTL (0x06) – The lower 8 bits of the 16 bit high threshold value.
  2. AIHTH (0x07) – The upper 8 bits of the 16 bit high threshold value.
• PERS (0x0C) – The APERS field (bits 3:0) allows the number of times the ALS interrupt threshold (AILT, AIHT) is exceeded before the interrupt is generated to be controlled. Setting a zero means an interrupt is generated on every ALS reading.
• The +/-25% button takes the current ambient light reading and automatically computes new values for the AILT and AIHT registers, each with a 25% wider latitude.

OUTPUT SIDE, “REGISTER” TAB

The value of internal registers is displayed on this tab. Register values cannot be set here. To set registers use the Register tab on the input side of the screen.

Controls are provided for clearing the ALS interrupt (AINT). The current interrupt status is also shown.

The CDATA, RDATA, GDATA, and BDATA are the ADC values from the Clear, Red, Green and Blue channel photodiodes. Each value is read via two 8-bit registers.

• Status (0x13) – Internal status. Interrupts active (2 bits) and ALS valid bits are here.
• ID (0x12) – The ID register provides the value for the part number.
• CDATA (0x14, 0x15):
  1. CDATA (0x14) – The lower 8 ADC bits of the Clear photodiode.
  2. CDATAH (0x15) – The upper 8 ADC bits of the Clear photodiode.
• RDATA (0x16, 0x17):
  1. IRDATA (0x16) – The lower 8 ADC bits of the Red photodiode.
  2. IRDATAH (0x17) – The upper 8 ADC bits of the Red photodiode.
• GDATA (0x18, 0x19):
  1. IRDATA (0x18) – The lower 8 ADC bits of the Green photodiode.
  2. IRDATAH (0x19) – The upper 8 ADC bits of the Green photodiode.
• BDATA (0x1A, 0x1B):
  1. IRDATA (0x1A) – The lower 8 ADC bits of the Blue photodiode.
  2. IRDATAH (0x1B) – The upper 8 ADC bits of the Blue photodiode.

OUTPUT SIDE, “FUNCTIONAL” TAB The Clear, Red, Green and Blue photodiodes output values are shown in ALS group.

OUTPUT SIDE, “PLOT” TAB

The Red, Green, Blue, and Clear photodiodes, can be displayed vs. time on the graph.

The graph shows all outputs for a static system. The X-axis plots 376 points then rolls over back to 1 on the graph. The Y-axis is set to range 0 to 1024; this range cannot be adjusted. However multipliers (selected from the list boxes) may be used to scale the display accordingly.

RESOURCES

• TCS3471 datasheet (included with EVM media)
• Quick Start Guide (QSG included with EVM media)
• Application Notes (available from website)

For additional information regarding the TCS3471, please refer to the datasheet. For information regarding the installation of the TCS3471 EVM host application please refer to the Quick Start Guide.

Application notes dealing with various aspects of optical measurement and optical measurement applications are available. All content is available on the TAOS website www.TAOSinc.com

TEXAS ADVANCED OPTOELECTRONIC SOLUTIONS (TAOS) PROVIDES CUSTOMER SUPPORT IN VARIED TECHNICAL AREAS. SINCE TAOS DOES NOT POSSESS FULL ACCESS TO DATA CONCERNING ALL OF THE USES AND APPLICATIONS OF CUSTOMERS’ PRODUCTS, TAOS ASSUMES NO RESPONSIBILITY FOR CUSTOMER PRODUCT DESIGN OR THE USE OR APPLICATION OF CUSTOMERS’ PRODUCTS OR FOR ANY INFRINGEMENTS OF PATENTS OR RIGHTS OF OTHERS WHICH MAY RESULT FROM TAOS’ ASSISTANCE.

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