EVAL-AD7156EBZ

Evaluation Kit for AD7156 Ultralow Power Capacitance Converter EVAL-AD7156 GENERAL DESCRIPTION This data sheet describes the AD7156 evaluation board and PC software. Additional details about the AD7156, an ultralow power, 2-channel capacitance-to-digital converter (CDC) are available in the AD7156 data sheet, which should be consulted in conjunction with this data sheet when using the EVAL-AD7156. More information about the Analog Devices, Inc., family of CDC products can be found at www.analog.com/CDC. EVALUATION BOARD DESCRIPTION The flexible interface structure of the evaluation board allows it to be connected in several useful configurations. For example, the digital section of the evaluation board can be used independently as a convenient digital interface for a user’s own sensor design PCB or as a module containing the AD7156. Alternatively, an external microcontroller can be interfaced to the AD7156. Thus, the evaluation board can act as a complete analog front end for creating and debugging software on the user’s own digital platform. 08159-001 The AD7156 evaluation kit is a powerful tool for exploring and evaluating the AD7156 features at many different levels. The board is connected to a PC via a standard USB interface. The PC software allows the graphical display of real-time data, modification of the AD7156 internal settings, and generally assists in understanding the part features and performance. Figure 1. AD7156 Evaluation Board Rev. 0 Evaluation boards are only intended for device evaluation and not for production purposes. Evaluation boards are supplied “as is” and without warranties of any kind, express, implied, or statutory including, but not limited to, any implied warranty of merchantability or fitness for a particular purpose. No license is granted by implication or otherwise under any patents or other intellectual property by application or use of evaluation boards. Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Analog Devices reserves the right to change devices or specifications at any time without notice. Trademarks and registered trademarks are the property of their respective owners. Evaluation boards are not authorized to be used in life support devices or systems. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. www.analog.com Tel: 781.329.4700 Fax: 781.461.3113 ©2009 Analog Devices, Inc. All rights reserved. EVAL-AD7156 TABLE OF CONTENTS General Description ......................................................................... 1  Setup Window ...............................................................................6  Evaluation Board Description......................................................... 1  Mode of Operation........................................................................6  Revision History ............................................................................... 2  Capacitive Input Settings..............................................................8  Evaluation Software Installation ..................................................... 3  Evaluation Board Schematic and Artwork.................................. 10  Evaluation Board Hardware ............................................................ 4  Component ID ............................................................................ 12  Power Supply ................................................................................. 4  Layout .......................................................................................... 12  I C Interface Configuration Options ......................................... 4  Ordering Information .................................................................... 13  Evaluation Board Software .............................................................. 5  Bill of Materials ........................................................................... 13  Starting the Evaluation Software ................................................ 5  Ordering Guide .......................................................................... 14  Data Acquisition Window ........................................................... 5  ESD Caution................................................................................ 14  2 REVISION HISTORY 6/09—Revision 0: Initial Version Rev. 0 | Page 2 of 16 EVAL-AD7156 EVALUATION SOFTWARE INSTALLATION Install the AD7156 evaluation board software before connecting the AD7156 evaluation board to the PC. To do so, complete the following steps: 2. 3. Follow the steps in the evaluation software installation wizard until the installation is completed. Connect the AD7156 evaluation board to your PC USB connector using the USB cable included in the evaluation kit. The POWER LED on the evaluation board turns on and the Found New Hardware Wizard starts automatically on the PC. Please install software before connecting board to USB port! E valuation kit docum entation including installation guideline m ay be found in file A D 7156E B .pdf on this C D AD7156 08159-002 08159-004 Evaluation Kit CD Figure 2. AD7156 Evaluation Kit CD 4. Follow the steps in the Found New Hardware Wizard window. If a message that the software has not passed Windows® Logo testing appears, click Continue Anyway. 08159-005 Insert the AD7156 evaluation kit CD in the CD-ROM drive of your PC. The evaluation software installation wizard should start automatically. If the wizard does not start, run Setup.exe from the AD7156 evaluation kit CD. Figure 5. Windows Logo Warning 08159-003 1. Figure 4. Found New Hardware Wizard 5. Figure 3. AD7156 Evaluation Software Installation Rev. 0 | Page 3 of 16 Follow the steps in the Found New Hardware Wizard window until the installation is completed. EVAL-AD7156 EVALUATION BOARD HARDWARE POWER SUPPLY AD7156 EVALUATION BOARD To use the AD7156 evaluation board, make sure that the link on the supply header (J7) is in place, either in V_EVB when using the on-board voltage supply or in V_EXT when using an external voltage source via J8. U1 U101 SDA MICROCONTROLLER SCL AD7156 In both cases, the LED labeled POWER on the board should turn on when connected to either of the supply sources. J5 I2C INTERFACE CONFIGURATION OPTIONS The AD7156 evaluation board allows different digital interface configurations by redirecting the I2C® signals, SDA and SCL, on J5. FINAL APPLICATION SDA Default AD7156 Links in the SDA and SCL positions of J5 connect the USB microcontroller as the I2C bus master to the on-board AD7156, as shown in Figure 6. This allows easy use of the evaluation board together with the PC software. AD7156 EVALUATION BOARD U101 SDA SCL Figure 7. AD7156 Evaluation Board as USB-to-I2C interface External Connection—AD7156 The AD7156 evaluation board can be used for software development by connecting a customer-specific external microcontroller board to Pin 5 and Pin 7 of J5, as shown in Figure 8, using the AD7156 CDC on the evaluation board as the sensing device. U1 MICROCONTROLLER 08159-007 SCL AD7156 AD7156 EVALUATION BOARD J5 08159-006 U1 U101 SDA MICROCONTROLLER SCL AD7156 Figure 6. AD7156 Evaluation Board in Default Configuration USB—External Connection J5 CUSTOMER BOARD SDA MICROCONTROLLER SCL 08159-008 The AD7156 evaluation board allows customers to connect their own specific AD7156 application board to Pin 6 and Pin 8 of J5. This enables customers, together with the PC evaluation software, to evaluate their application hardware using the AD7156 evaluation board only as a USB-to-I2C digital interface as shown in Figure 7. Figure 8. AD7156 Evaluation Board Software Development Platform Rev. 0 | Page 4 of 16 EVAL-AD7156 EVALUATION BOARD SOFTWARE STARTING THE EVALUATION SOFTWARE Start Acquisition Start the AD7156 evaluation software on the PC. Clicking the green Start Acquisition button in the AD7156 evaluation software window starts the data acquisition. The LED labeled RUN on the evaluation board turns on, the RUN indicator in the top right corner of the software window turns on red, and graphs in the software start displaying the measured data. Click the Start button, located at the bottom left-hand corner of your desktop. Select Programs, then Analog Devices, then AD7156 Evaluation Software, and then AD7156EB to run the software. If a connection between the software and the evaluation board is correctly established, the window shown in Figure 9 appears. The USB indicator in the top right corner of the software window turns on green, and the LED labeled RUN on the AD7156 evaluation board flashes in approximately 1 sec intervals. DATA ACQUISITION WINDOW Reset When Reset is clicked, the software accesses AD7156 Register Address 0xBF to reset the part. See the AD7156 data sheet for details on the serial interface. The data displays and the traces in the graphs represent realtime data read from the AD7156. Graphs The graphs show the history of data of up to 65,536 samples. You can modify the graph appearance. For example, the scale can be modified by typing minimum and maximum numbers when the autoscale is turned off. Place the cursor on the graph and right-click the mouse to open the graph submenu, which allows different individual graph settings. When Clear Graphs is clicked, the graph and the graph history are cleared. Demo Setup Data Format and Units Clicking on Demo Setup configures the AD7156 to its default settings, as shown in Figure 10. Both displays show the data as hexadecimal codes read from the AD7156 and translated to picofarads (pF). The graphs can show the data in either hexadecimal codes or translated in picofarads. To switch between these two modes, click Display pF. The Display pF button switches to Display Code when clicked. Setup Click Setup to open the AD7156 setup window (see Figure 10), which provides access to the AD7156 settings. Log Data to File 08159-009 When Log data to file is clicked, the software allows you to log the acquisition data into a text file with the ASCII tab character as the delimiter to allow easy import to a data processing tool, such as Microsoft® Excel. Figure 9. AD7156 Evaluation Software Data Acquisition Window Rev. 0 | Page 5 of 16 EVAL-AD7156 08159-010 SETUP WINDOW Figure 10. AD7156 Evaluation Software Setup Window Register Field OK The register section of the setup window (left portion of the window) indicates the address, register name, and the current content in hexadecimal form for each AD7156 register. When OK is clicked, the evaluation software writes the current settings into the AD7156 registers, the setup window closes, and the software returns to the data acquisition window. Reset Cancel When Reset is clicked, the software accesses AD7156 Register Address 0xBF to reset the part. See the AD7156 data sheet for details on the serial interface. When Cancel is clicked, the evaluation software writes the register settings that were buffered from the time the setup window was opened into the AD7156 registers. The setup window then closes and the software returns to the data acquisition window. Demo Setup A click on Demo Setup configures the AD7156 to its default settings as shown in Figure 10. MODE OF OPERATION Mode Write When Write is clicked, the evaluation software writes the current settings shown in the setup window into the AD7156 registers. The Mode box allows you to put the AD7156 into the following operating modes: • Read When Read is clicked, the evaluation software reads the current register content of the AD7156 registers and the updates are shown in the setup window. • Save to File • When Save to File is clicked, a window opens to allow the current settings to be saved to a text file. Read from File When Read from File is clicked, a window opens to allow you to read back previously saved settings from a text file. • Vdd The Vdd box allows you to set the supply voltage for AD7156 within its specified limits between 1.8 V and 3.6 V. The default setting for the supply voltage is 3.3 V. Rev. 0 | Page 6 of 16 Standby mode (idle). The part is fully powered up, but not performing any conversion. Continuous conversion. The part is repeatedly performing conversions on the enabled channel(s). If two channels are enabled, the part is sequentially switching between them. Single conversion. The part performs a single conversion on the enabled channel. If two channels are enabled, the part performs two conversions, one on each channel. After finishing the conversions, the part goes to standby mode (idle). Power-down. Powers down the on-chip circuits, except the digital interface. EVAL-AD7156 Threshold Modes Positive Threshold The upper Threshold box allows you to set the AD7156 threshold to either adaptive or to fixed see Figure 17. The positive threshold is set above the average, used when a positive change on the capacitive input is expected. The change on the input is indicated when the input data goes above the threshold. When the upper mode box is set to adaptive mode, the lower Threshold box allows you to define the threshold level to be positive, negative, in-window, or out-window see Figure 17. POSITIVE CHANGE POSITIVE THRESHOLD Adaptive Mode In adaptive mode, the thresholds are dynamically adjusted, ensuring indication of fast changes (for example, an object moving close to a capacitive proximity sensor) and eliminating slow changes in the input (sensor) capacitance, usually caused by environment changes such as humidity or temperature. FAST CHANGE INPUT CAPACITANCE 08159-014 OUTPUT ACTIVE OUTPUT TIME Figure 14. Positive Threshold Mode Indicates Positive Change in Input Capacitance SLOW CHANGE INPUT CAPACITANCE In-Window Threshold THRESHOLD OUTPUT ACTIVE 08159-011 OUTPUT TIME Figure 11. Adaptive Threshold Indicates Fast Changes and Eliminates Slow Changes in Input Capacitance The in-window threshold has two thresholds, one above and one below the average. The output stays high as long as the input data stays inside threshold window. A change on the input is indicated by a low on the output when the input data goes either above the positive threshold or below the negative threshold. POSITIVE THRESHOLD Fixed Mode INPUT INSIDE THRESHOLD WINDOW INPUT CAPACITANCE In fixed mode, the threshold is fixed to a defined value, and changes in the input capacitance are indicated when the input data crosses the fixed threshold. NEGATIVE THRESHOLD OUTPUT ACTIVE FAST CHANGE 08159-015 OUTPUT SLOW CHANGE INPUT CAPACITANCE TIME Figure 15. In-Window (Adaptive) Threshold Mode THRESHOLD Out-Window Threshold OUTPUT 08159-012 OUTPUT ACTIVE TIME Figure 12. AD7156 in Fixed Mode The out-window threshold has two thresholds, one above and one below the average. A change on the input is indicated when the input data goes either above the positive threshold or below the negative threshold. Negative Threshold INPUT OUTSIDE THRESHOLD WINDOW The negative threshold is set below the average, used when a negative change on the capacitive input is expected. The change on the input is indicated when the input data goes below the threshold. POSITIVE THRESHOLD INPUT CAPACITANCE NEGATIVE THRESHOLD 08159-016 OUTPUT ACTIVE NEGATIVE CHANGE INPUT CAPACITANCE OUTPUT NEGATIVE THRESHOLD TIME Figure 16. Out-Window (Adaptive) Threshold Mode TIME 08159-026 OUTPUT 08159-013 OUTPUT ACTIVE Figure 13. Negative Threshold Mode Indicates Negative Change in Input Capacitance Rev. 0 | Page 7 of 16 Figure 17. Threshold Mode Select Options EVAL-AD7156 DATA CAPACITIVE INPUT SETTINGS The AD7156 has two capacitive input channels that can be set up independently via the I2C-compatible interface. These AD7156 settings are described in the following sections and are valid for both channels. POSITIVE THRESHOLD SENSITIVITY DATA AVERAGE SENSITIVITY NEGATIVE THRESHOLD 08159-019 OUTPUT ACTIVE TIME Figure 20. Threshold Sensitivity Timeout Approaching, Timeout Receding The Timeout Approaching box and Timeout Receding box allow you to set a time after which the adaptive average and the threshold adapt to a fast and seemingly permanent change in input capacitance to ensure normal operation after the event. 08159-017 TIMEOUT APPROACHING INPUT CAPACITANCE THRESHOLD Figure 18. AD7156 Capacitive Input Setup DATA AVERAGE Ch1, Ch2 OUTPUT Cin Range TIME 08159-020 OUTPUT ACTIVE The Ch1 and Ch2 boxes allow you to enable or disable the capacitive input channels individually. Figure 21. Approaching Timeout in Negative Threshold Mode Shortens False Output Trigger The Cin Range box allows you to select the following capacitive input ranges for each channel: 4 pF, 2 pF, 1 pF, or 0.5 pF. TIMEOUT RECEDING Hysteresis The Hysteresis box allows you to enable or disable threshold hysteresis when operating in adaptive mode. The hysteresis is fixed to ±¼ of the threshold sensitivity and can be programmed on or off. DATA LARGE CHANGE INPUT CAPACITANCE THRESHOLD POSITIVE THRESHOLD OUTPUT ACTIVE OUTPUT TIME DATA AVERAGE 08159-021 HYSTERSIS Figure 22. Receding Timeout in Negative Threshold Mode Shortens Period of Missing Output Trigger OUTPUT TIME 08159-018 OUTPUT ACTIVE The number of conversion cycles, NC, required for the timeouts to elapse can be calculated using the following equation: Figure 19. Threshold Hysteresis ⎛ 2 16 − 1 ⎞ ⎟ with P value of register nibble N C = Roundup⎜ 15 − P + 1 ⎜2 − 1 ⎟⎠ ⎝ Threshold Sensitivity The Threshold Sensitivity box allows you to set a defined sensitivity. This is defined as the distance between the data average and the threshold in codes, as a fixed portion in the range of the lower eight bits out of the 12-bit CDC full-scale range of 0xA000 codes (d40944). Therefore, it represents a different capacitive input value for each capacitive input range. Average Time Constant The Average Time Constant box allows you to determine how fast the moving average adjusts to changes of the capacitive input data. The adaptive threshold algorithm is based on an average calculated from the previous CDC output data, using the following equation: Average(N ) = Average(N − 1) + Rev. 0 | Page 8 of 16 Data(N ) − Average(N − 1) 2 ThrSettling + 1 EVAL-AD7156 CapDAC The CapDAC box allows you to enable the CAPDACs that compensate for capacitive offsets on the input (nonchanging). The CapDAC Value box contains the current CAPDAC value set by the autoDAC. It also allows you to set the value when the autoDAC function is disabled. The CapDAC Auto box enables the autoDAC function, which ensures that the data input stays within 25% to 75% of the selected capacitive input range. Rev. 0 | Page 9 of 16 EVAL-AD7156 EVALUATION BOARD SCHEMATIC AND ARTWORK 08159-022 Figure 23. AD7156 Evaluation Board Schematic—Analog Part Rev. 0 | Page 10 of 16 EVAL-AD7156 08159-023 Figure 24. AD7156 Evaluation Board Schematic—Digital Part Rev. 0 | Page 11 of 16 EVAL-AD7156 08159-024 COMPONENT ID Figure 25. AD7156 Evaluation Board Layout—Silkscreen 08159-025 LAYOUT Figure 26. AD7156 Evaluation Board Layout—Component Side Rev. 0 | Page 12 of 16 EVAL-AD7156 ORDERING INFORMATION BILL OF MATERIALS Table 1. Bill of Materials Designator PCB U1 U2 Qty 1 1 1 U3 1 U4 U5 U101 1 1 1 U102 U103 D1 Q3, Q4 LED1 LED2 LED101, LED102 Y101 V1 to V4 C1 to C4 C5 to C7, C11, C14, C107 C12, C104 to C106 C13, C101, C102 C103 C108 to C118 R1 to R4, R12, R13, R16 R5 R6 R7, R8 R9, R10 R11 R14, R15, R18 R101, R102 R103, R104 R105 to R107, R109, R110 R108, R111 J1 to J4 J1 to J4 J5 J5 J6 J7 J7 J8 J101 CIN1, CIN2, EXC1, EXC2 B1 1 1 1 2 1 1 2 1 4 4 6 4 1 2 1 11 7 1 1 2 2 1 3 2 2 5 2 4 4 1 2 1 1 1 1 1 4 1 4 Description 2-layer FR4 PCB,1.6 mm × 75 mm × 115 mm CDC for proximity sensing, 10-lead MSOP Nonvolatile 256-position digital potentiometer, 10-lead MSOP Voltage regulator, adjustable voltage, low IQ, 8-lead MSOP 0.5 Ω CMOS dual 2:1 MUX/SPDT audio switch Mux Microcontroller, EZ-USB FX2LP microcontroller, 56-lead QFN EEPROM, I2C, 64 kb, 8-DFN Voltage regulator, 3.3 V, low IQ, SOT-23-6 Diode, Schottky, 40 V, 0.2 A, SOT-23 Transistor, N-MOSFET, 60 V, 0.23A, SOT-23 LED, red, high intensity (>100 mCd), 0805 LED, orange, high intensity (>100 mCd), 0805 LED, green, high intensity (>50 mCd), 0805 Crystal, 24 MHz, 12 pF, CMS-8 series Protection component, 0402 Capacitor ceramic Capacitor ceramic, 0.1 μF, 16 V, X7R, 0603 Capacitor ceramic,10 μF, 6.3 V, X5R, 0603 Capacitor ceramic, 2.2 μF, 16 V, X5R, 0603 Capacitor ceramic, 12 pF, 50 V, C0G, 0402 Capacitor ceramic, 1 μF, 6.3 V, X5R, 0402 Capacitor ceramic, 0.1 μF, 16 V, X7R, 0402 Resistor, 0.0 Ω, 0603 Resistor, 100 Ω, 1%, 0603 Resistor, 62 kΩ, 1%, 0603 Resistor, 1.0 kΩ, 1%, 0603 Resistor, 100 kΩ, 1%, 0603 Resistor, 36 kΩ, 1%, 0603 Resistor Resistor, 1.0 kΩ, 1%, 0402 Resistor, 2.2 kΩ, 1%, 0402 Resistor, 100 kΩ, 1%, 0402 Resistor, 10 kΩ, 1%, 0603 Header, straight, 2.54 mm pitch, 1 × 3-pin Jumper, 2-way, 2.54 mm pitch Header straight, 2.54 mm pitch, 2 × 5-pin Jumper, 2-way, 2.54 mm pitch Header, straight, 2.54 mm pitch, 1 × 4-pin Header, straight, 2.54 mm pitch, 2 × 2-pin Jumper, 2-way, 2.54 mm pitch 2-pin terminal block, 5 mm pitch Connector, USB Mini-B, SMD Connector, SMB 50 Ω, PCB straight Clip for 9 V battery, PCB mounting Feet, stick-on, 9.5 mm diameter, 3.8 mm height Rev. 0 | Page 13 of 16 Manufacturer Analog Devices Analog Devices Part No. EVAL-AD7156EBZ AD7156BCPZ AD5259BCPZ Analog Devices ADP1720ARMZ Analog Devices Not inserted Cypress ADG884BRMZ-REEL7 Not inserted CY7C68013A-56LFXC Microchip Analog Devices Philips Infineon Kingbright Kingbright Kingbright ECS Not inserted Not inserted Murata Murata Murata Murata Murata Murata Phycomp Phycomp Vishay Phycomp Phycomp Vishay Not inserted Phycomp Phycomp Phycomp Phycomp Samtec FCI OUPIIN FCI Samtec Samtec FCI Lumberg Molex Amphenol Keystone 3M 24LC64T-I/MC ADP3330ARTZ3.3 BAT721C BSS138N KP-2012SURC KP-2012SEC KP-2012MGC ECS-240-12-20A-TR Not inserted Not inserted GRM188R71C104K GRM188R60J106M GRM188R61C225K GRM1555C1H120J GRM155R60J105K GRM155R71C104K 232270296001 232270461001 CRCW060362K0FKEA 232270461002 232270461004 CRCW060336K0FKEA Not inserted 232270671002 232270672202 232270671004 232270671003 TSM-103-01-T-SV 68786-202LF 3012-A10G00DBA 68786-202LF TSM-104-01-T-SV TSM-102-01-T-DV 68786-202LF KRM 02 54819-0578 SMB1251B1-3GT30G-50 593+594 SJ5306TRANS EVAL-AD7156 ORDERING GUIDE Model EVAL-AD7156EBZ1 1 ESD CAUTION Description Evaluation Board Z = RoHS Compliant Part. Rev. 0 | Page 14 of 16 EVAL-AD7156 NOTES Rev. 0 | Page 15 of 16 EVAL-AD7156 NOTES Purchase of licensed I2C components of Analog Devices or one of its sublicensed Associated Companies conveys a license for the purchaser under the Philips I2C Patent Rights to use these components in an I2C system, provided that the system conforms to the I2C Standard Specification as defined by Philips. ©2009 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. EB08159-0-6/09(0) Rev. 0 | Page 16 of 16