Texas Instruments LDC131 Series User manual

LDC131x and LDC161x EVM User’s Guide
User's Guide
Literature Number: SNOU133
December 2014

Contents
1 Overview............................................................................................................................. 5
2 Quick Start Guide LDC131x/161x Evaluation Module................................................................ 6
2.1 LDC131x/161x Evaluation Module Overview......................................................................... 6
2.1.1 Set Up Requirements........................................................................................ 6
2.1.2 Loading and Running ........................................................................................ 6
3 Inductive Sensing GUI User’s Guide....................................................................................... 8
3.1 Inductive Sensing GUI Overview....................................................................................... 8
3.2 Host Platform Requirements............................................................................................ 8
3.3 Installation Process ...................................................................................................... 8
3.4 Reconnecting the EVM.................................................................................................. 8
3.5 EVM Information.......................................................................................................... 8
3.6 Icon Toolbar............................................................................................................... 9
3.7 Configuration Tab....................................................................................................... 10
3.8 Registers Tab ........................................................................................................... 11
3.9 Error Tab................................................................................................................. 12
3.10 Data Streaming ......................................................................................................... 13
3.10.1 Average, Point, Min, Max Values ......................................................................... 13
3.10.2 Zooming and Scaling....................................................................................... 13
3.10.3 Frequency Count............................................................................................ 14
3.11 Saving and Loading .................................................................................................... 14
3.11.1 Configurations............................................................................................... 14
3.11.2 Plot Data ..................................................................................................... 14
3.11.3 Data Logging ................................................................................................ 15
3.12 Input Clock Options..................................................................................................... 15
3.13 Using Multiple EVMs Simultaneously................................................................................ 15
3.14 EVM Sensors............................................................................................................ 16
4 LDC1312/1612 EVM Schematics and Layout .......................................................................... 18
5 LDC1314/1614 EVM Schematics and Layout .......................................................................... 23
6 Bill of Materials .................................................................................................................. 28
Revision History.......................................................................................................................... 36
2Table of Contents SNOU133–December 2014
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List of Figures
1 LDC1312/1612 Evaluation Module........................................................................................ 5
2 Perforations of the Evaluation Module.................................................................................... 5
3 System Level Diagram of EVM ............................................................................................ 6
4 Configuration and Streaming Icons........................................................................................ 6
5 Configuration Registers..................................................................................................... 7
6 Start Streaming .............................................................................................................. 7
7 Streaming Data from Two Channels ...................................................................................... 7
8 Icon Toolbar .................................................................................................................. 9
9 Configuration Section...................................................................................................... 10
10 Reading and Setting Values .............................................................................................. 10
11 Register Settings ........................................................................................................... 11
12 Read/Write Register Dialog............................................................................................... 11
13 Error Tab .................................................................................................................... 12
14 Error Configuration......................................................................................................... 12
15 Streaming Configuration................................................................................................... 13
16 Switching Display Units between Inductance and Frequency Count................................................ 14
17 Save Icon.................................................................................................................... 14
18 Open Icon ................................................................................................................... 14
19 Data Logging................................................................................................................ 15
20 EVM LC Tanks ............................................................................................................. 16
21 Plots of L and R vs. Frequency........................................................................................... 16
22 Plots of Q vs. Frequency.................................................................................................. 17
23 Sensor Capacitor Setting.................................................................................................. 17
24 LDC1312/1612 USB Connection......................................................................................... 18
25 LDC1312/1612 Power Circuit............................................................................................. 18
26 LDC1312/1612 Clocking .................................................................................................. 19
27 LDC1312/1612.............................................................................................................. 19
28 LDC1312/1612 MSP430 Connections................................................................................... 20
29 LDC1312/1612 Layout Top Layer – Signals and Components ...................................................... 21
30 LDC1312/1612 Layout MidLayer 1 – Ground Plane................................................................... 21
31 LDC1312/1612 Layout MidLayer 2 – Signals and Power Plane..................................................... 22
32 LDC1312/1612 Layout Bottom Layer – Signals Plane ................................................................ 22
33 LDC1314/1614 USB Connection......................................................................................... 23
34 LDC1314/1614 Power Circuit............................................................................................. 23
35 LDC1314/1614 Clocking .................................................................................................. 24
36 LDC1314/1614.............................................................................................................. 24
37 LDC1314/1614 MSP430 Connections................................................................................... 25
38 LDC1314/1614 Layout Top Layer – Signals and Components ...................................................... 26
39 LDC1314/1614 Layout MidLayer 1 – Ground Plane................................................................... 26
40 LDC1314/1614 Layout MidLayer 2 – Signals and Power Plane..................................................... 27
41 LDC1314/1614 Layout Bottom Layer – Signals Plane ................................................................ 27
3
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List of Tables
1 Icon’s Description............................................................................................................ 9
2 Modes Description ......................................................................................................... 13
3 Zooming and Scaling Options ............................................................................................ 13
4 BOM for LDC1312 EVM................................................................................................... 28
5 BOM for LDC1612 EVM................................................................................................... 30
6 BOM for LDC1314 EVM................................................................................................... 32
7 BOM for LDC1614 EVM................................................................................................... 34
4List of Tables SNOU133–December 2014
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Perforation # 2
Perforation # 1
Perforation # 3
MSP430
Channel 0 Sensor Connector for custom coil
330pF capacitor
LDC131x/161x IC
LEDs
Channel 1 Sensor
User's Guide
SNOU133–December 2014
LDC131x and LDC161x EVM User’s Guide
1 Overview
The LDC131x/161x EVM demonstrates the use of inductive sensing technology to sense and measure the
presence or position of conductive target objects. The EVM contains two example LC tank sensors that
are connected to the LDC131x/161x input channels. The latter is controlled by an MSP430, which
interfaces to a host computer.
Figure 1. LDC1312/1612 Evaluation Module
The LDC1312/1612 EVM includes two example PCB sensors which are PCB inductors with 330 pF 1%
COG/NP0 capacitors connected in parallel to form an LC tank. LDC1314/1614 includes two additional
spaces to which two sensors can be connected.
When the evaluation module first powers up from the USB port, it will flash a series of green and red LED
lights to indicate self-test. When the self-test is finished, the green LED turns on, which indicates the
connection of the EVM to the host computer.
Figure 2. Perforations of the Evaluation Module
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Streaming Icon
Configuration Icon
LDO 3.3V
LDC131x/161x MSP430
Clocking
LDO 1.8V
I2C
5V
Sensor 0
Sensor 1
Perforation # 2 Perforation # 3
3.3V
Sensor 3(*)
Sensor
4
(*)
* Available only for LDC1314
and LDC1614
Quick Start Guide LDC131x/161x Evaluation Module www.ti.com
2 Quick Start Guide LDC131x/161x Evaluation Module
This section describes how to properly connect, set up and use the LDC131x/161x EVM.
2.1 LDC131x/161x Evaluation Module Overview
The LDC131x/161x Evaluation Module enables the user to test out the capabilities of the LDC131x/161x,
Inductance-to-Digital Converter. The EVM is a micro USB device used with a host computer and
configured using the Inductive Sensing Graphical User Interface (GUI) software.
Figure 3. System Level Diagram of EVM
2.1.1 Set Up Requirements
The LDC131x/161x GUI and drivers must be installed on the host. Driver installation will launch
automatically once the device is plugged in. See Section 3.3 for more information on software installation.
2.1.2 Loading and Running
1. Plug the EVM into the host computer. The host computer should automatically detect the device as a
LDC131x/161xEVM.
2. Launch the GUI. It should automatically detect the presence of the EVM.
3. By default, GUI is configured to stream in single channel mode. To stream the data from both
channels, change Channel Config in the Configuration tab. First, select Configuration on the icon
toolbar.
Figure 4. Configuration and Streaming Icons
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www.ti.com Quick Start Guide LDC131x/161x Evaluation Module
4. By default, the EVM will be performing conversions only on Channel 0 and Channel 1. If other channel
conversion is desired, select the appropriate channel in the Channel Config toolbar: Go back to the
Streaming tab.
Figure 5. Configuration Registers
5. Select Start in order to begin streaming the data.
Figure 6. Start Streaming
6. The data will update in the graph shown in Figure 7: Zoom into each tab if needed by right clicking on
it and selecting "Zoom to".
Figure 7. Streaming Data from Two Channels
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Inductive Sensing GUI User’s Guide www.ti.com
3 Inductive Sensing GUI User’s Guide
3.1 Inductive Sensing GUI Overview
The inductive sensing GUI provides graphical configuration and streaming support for the LDC131x/161x.
The GUI package includes drivers for use with the EVM. The EVM provides a device abstraction layer for
the GUI to communicate with the LDC131x/161x through I2C, and includes other extended functionality.
3.2 Host Platform Requirements
The Inductive Sensing GUI supports:
• 32-bit and 64-bit Windows 7
• 32-bit and 64-bit Windows XP
The host machine is required for device configuration and data streaming. The following steps are
necessary to prepare the EVM for the GUI:
• The GUI must be installed on the host.
• The EVM driver must be installed on the host.
• The EVM must be connected to a full speed USB port (USB 1.0 or above).
3.3 Installation Process
The EVM GUI can be downloaded from the TI website. Select LDC131x/161x-SW for software installation.
3.4 Reconnecting the EVM
If the EVM is disconnected from the host at any time, simply reconnect the device and the GUI will
automatically discover and re-establish the streaming abilities with the device. Connecting an EVM of a
different device (LDC1312, LDC1612, LDC1314, or LDC1614) requires GUI restart.
3.5 EVM Information
EVM Information
• Configure register data through I2C (SCL, SDA)
• Stream registers data through I2C
• Detect interrupts through I2C
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3.6 Icon Toolbar
The icon toolbar contains various icons which navigate between sections and perform various functions.
Figure 8. Icon Toolbar
Table 1. Icon’s Description
ICON FUNCTION DESCRIPTION
• EVM is connected
Indicates whether an EVM is connected to
Connection State the PC, and if so, provides details of the
• EVM is disconnected connected EVM
Opens saved register settings and
Open defaults
Saves all current register settings and
Save defaults
Register Settings Show LDC131x/161x Register Settings
Configuration Show EVM Configuration
Streaming Show Streaming Section
Error Window Show Error Section
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3.7 Configuration Tab
In the configuration section, the device functionality can be viewed and modified. Stop streaming before
making any changes on the tab.
Figure 9. Configuration Section
In the Configuration tab, select the parameter to change. Changes are applied immediately.
• Press “Read All” to refresh all configuration, status, and data settings.
• Press “Restore from Defaults” to write values from the default column (if they exist) to the current
register values.
• Press "Save Values as Defaults" to restore the current configuration to the default settings.
Figure 10. Reading and Setting Values
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3.8 Registers Tab
In the register settings section, all registers of the device can be accessed. Register settings can be
modified in either configuration or register tabs. Note that registers tab takes hexadecimal values, whereas
the configurations tab works with decimal values. Alike the configurations tab, access to the settings is
available after the streaming is stopped.
Figure 11. Register Settings
Double-click on a register in the table to read/write. If a register is read only, the selected register is read
immediately and the table value updated. If the register is read/write, a dialog pops up and the user can
set a new register value. If the value is not changed, it will default to a read.
Figure 12. Read/Write Register Dialog
• Press: “Save Values as Default” to save all configuration, status, and data.
• Press: “Restore from Defaults” to write values from the default column (if they exist) to the current
register value.
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3.9 Error Tab
In the error window sections, all device errors can be monitored. Error conditions are highlighted in red.
Green area indicates no errors were detected.
Figure 13. Error Tab
Ensure that errors are reported by selecting ‘Unmask’ the error in the configuration tab:
Figure 14. Error Configuration
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3.10 Data Streaming
Data is streamed from the EVM to the GUI when streaming is started. The sampling rate of the EVM and
the number of samples to plot can be configured. The sampling rate is the rate at which the
microcontroller on the EVM retrieves a measurement from the LDC131x/161x.
Figure 15. Streaming Configuration
The sampling rate can only be set when streaming is stopped. The limit on the sampling rate is 1000
times per second (1ms). For data logging, it is 100 times per second (10ms).
3.10.1 Average, Point, Min, Max Values
Average is the default display type. To toggle between sample point, min, and max values, right-click on
the plot region of the GUI. The various display modes are:
Table 2. Modes Description
NAME of the MODE FUNCTION of the MODE
Average Mode The average of all the data points currently in the plot
Point Mode The newest data point value currently in the plot
Min Mode The minimum data point value currently in the plot
Max Mode The maximum data point value currently in the plot
Standard Dev The standard deviation of the data currently in the plot
A larger number of samples results in a larger averaging window.
3.10.2 Zooming and Scaling
Plots are interactive. Zooming options are available by right-clicking the plot and selecting an option from
the context menu.
Table 3. Zooming and Scaling Options
NAME of the TYPE FUNCTION of the TYPE
Toggle Data Type Displays inductance thresholds
Zoom to... Zooms to window
Autoscale Autoscales the data in the plot
Save Plot Data… Allows to save the streaming data to a file
Reset Resets the Zoom window to its default setting
Clear Data Clears the data and resets streaming
Help Clears the data and resets streaming
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3.10.3 Frequency Count
To display the raw frequency count output data instead of the inductance data, right click on the
Inductance plot and select "Toggle Data Type".
Figure 16. Switching Display Units between Inductance and Frequency Count
3.11 Saving and Loading
3.11.1 Configurations
Configurations can be saved and loaded. To save a configuration, click on the: "Save" icon in the toolbar.
Type a name for the file.
Figure 17. Save Icon
Configurations include all register names, current values, and default values. They are saved in Comma-
Separated Files (*.csv) and can be modified using a text or spreadsheet editor.
To load a configuration, click on the "Open" icon in the toolbar and select the configuration file:
Figure 18. Open Icon
3.11.2 Plot Data
Right-click a plot and select “Save Data…”
Data can be saved to a new file or an existing one. If an existing file is chosen, data will be appended.
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3.11.3 Data Logging
Measured data from the LDC131x/161x EVM can be saved to a text file by using the logging features,
which are located on the bottom of the main GUI window.
Figure 19. Data Logging
The data is saved in a comma separated text file which contains the time of data capture, the inductance
measurement, and the raw inductance data. Data can be logged either as a single measurement or as a
continuous stream of data. To save a single measurement, set the middle button to "Single". If a
continuous log is desired, change the setting to "Continuous". Once the mode is set, press the "Log Data"
button to save the file. A file save dialogue will open asking for the file name. It is recommended to add
".txt" to the end of the filename if a text editor is to be used to analyze the data, or use an extension of
".csv" if a spreadsheet program is to be used. When the Logging save mode is continuous, the GUI will
continuously save the data from the LDC131x/161x EVM. To stop the data saving, press the "Log Data"
button a second time.
3.12 Input Clock Options
By default, the input clock for LDC131x/161x is generated externally by PLL clock synchronizer and has a
value of 40 MHz. It is possible to remove R11 and connect an external clock by populating J2.
3.13 Using Multiple EVMs Simultaneously
To connect multiple EVMs to a single host, multiple instances of the GUI should be launched. Each EVM
will interface to only one instance of the GUI. Use the following procedure to setup multiple EVMs:
1. Connect the desired number of EVMs to the available USB ports.
2. Open one instance of the GUI; note the COM port number at the top of the GUI. This EVM is the
highest priority. Remove and replace each EVM individually until the COM port number changes. Note
the new COM port number.
3. This EVM is the next highest priority. Repeat this process until no EVMs are connected and the EVM
with the lowest priority have been identified.
4. When all of the EVMs are to be used simultaneously, open one GUI for each EVM and plug in the
EVMs from lowest priority to highest priority – each will claim their own instance of GUI.
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3.14 EVM Sensors
The sensor portion of the LDC131x/161x Evaluation Module is perforated so that it can be snapped off
and replaced with custom LC tanks. The EVM includes two 2 layer, 32 turn, 14mm diameter inductors with
330pF 1% COG/NP0 capacitors. The Inductance and series resistance of the LC tank is plotted versus
frequency below.
Figure 20. EVM LC Tanks
Figure 21. Plots of L and R vs. Frequency
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Figure 22. Plots of Q vs. Frequency
When the sensor capacitor value is changed as a result of replacing the default LC tank with a custom
inductive sensor, it is necessary to input the new capacitor value into the Sensor Capacitor field in the GUI
to ensure that the inductance data is calculated correctly.
Figure 23. Sensor Capacitor Setting
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LDC1312/1612 EVM Schematics and Layout www.ti.com
4 LDC1312/1612 EVM Schematics and Layout
Figure 24. LDC1312/1612 USB Connection
Figure 25. LDC1312/1612 Power Circuit
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www.ti.com LDC1312/1612 EVM Schematics and Layout
Figure 26. LDC1312/1612 Clocking
Figure 27. LDC1312/1612
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Figure 28. LDC1312/1612 MSP430 Connections
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