EVAL-AD7143-1EBZ Analog Devices Inc, EVAL-AD7143-1EBZ Datasheet

Page 1

... Rev. 0 Evaluation boards are only intended for device evaluation and not for production purposes. Evaluation boards as 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 ...

Page 2

... CDC Converter Dialog Box...................................................... 15 Calibration Engine Dialog Box ................................................ 16 Excitation Source Dialog Box ................................................... 19 Ambient Compensation Dialog Box ....................................... 20 Interrupt Configuration Registers Dialog Box....................... 21 Power Control Dialog Box ........................................................ 22 CDC Status Register................................................................... 23 Setup Registers............................................................................ 24 Evaluation Board Schematics and Artwork ................................ 25 Ordering Information.................................................................... 28 Ordering Guide .......................................................................... 28 ESD Caution................................................................................ 28 Rev Page ...

Page 3

... V and 3.6 V. The AD7143 is available in a 16-lead × LFCSP-VQ and operates from a 2 3.6 V supply. The operating current consumption is less than 1 mA, falling to 50 μA in low power mode (conversion interval of 400 ms). Rev Page EVAL-AD7143 2 C serial interface operating voltages ...

Page 4

... Figure block diagram of the AD7143 evaluation board, showing all the main components and how they are connected. Figure 22 shows the silkscreen for the evaluation board to aid in locating components on the board. The main component on the board is the AD7143 capacitive- to-digital converter connected to eight capacitance sensors forming one scroll wheel ...

Page 5

... mini-USB socket. The USB cable should be connected to this socket. The USB signals, D+ and D−, along with power and ground for the evaluation board, are also connected to this socket 4-way header connector. Power and ground signals, along with RxD and TxD signals from the ADuC841, are available on this connector ...

Page 6

... Analog Devices. To download the firmware to the ADuC841, the user must use the software serial download utility program, called WSD, which installs as part of the evalua- tion software. A cable is required to connect the PC serial port to the evaluation board. This cable, EVAL-ADUC-CABLE1, is available from Analog Devices ...

Page 7

... INSTALLING THE SOFTWARE The software should be installed before the evaluation board is plugged into the host computer. The evaluation software is installed by running the AD7143EvaluationSoftwareInstall.exe program, found at www.analog.com/AD7143, under the Evaluation Boards heading. The user must agree to the Analog Devices licensing agreement before the software will install ...

Page 8

... The Control tab provides access to the conversion and control registers on the AD7143, whereas the Scrollwheel tab shows the eight segment sensors that form the scroll wheel. TURNS BLUE IF CLICKED. TURNS RED WHEN WHEEL IS CLICKED. Figure 3. Evaluation Demo Mode Configuration Dialog Box, Demo Tab Rev Page HAND INDICATES FINGER POSITION. ...

Page 9

... If proximity is set for a period longer than the Low Power Mode Timer Control value in low power mode, or longer than the Full Power Mode Timer Control value in full power mode, the AD7143 automatically recalibrates the on-chip algorithm. Rev Page EVAL-AD7143 ...

Page 10

... EVAL-AD7143 Figure 4. Evaluation Demo Mode Configuration Dialog Box, Control Tab Rev Page ...

Page 11

... BLUE BARS INDICATE THE AMPLITUDE MEASURED BY EACH ONE OF THE EIGHT SEGMENTS. Figure 5. Evaluation Demo Mode Configuration Dialog Box, Scrollwheel Tab The absolute position value is also shown as a number between 0 and 127. The scroll wheel requires eight sequencer stages on the AD7143: one for each segment represented S7. The level measured by each of the segments on the scroll wheel is shown at the bottom left side of the screen ...

Page 12

... The calibration engine contains blocks that represent the calibration setup for each sequencer stage. The AD7143 has many registers that must be programmed for the part to function correctly. The AD7143 evaluation software has an easy setup utility that programs the AD7143 registers with appropriate setup values. This utility is run by clicking Easy SetUp at the lower left of the Register Configuration dialog box ...

Page 13

... CDC. Each of the segments of the scroll wheel on the AD7143 evaluation board can be set up to use one sequencer stage in a similar manner. For more information on configuring the sequencer stage connection setups for particular sensors, see the Conversion Sequencer section of the AD7143 data sheet ...

Page 14

... EVAL-AD7143 Analog Front-End Offset Control To ensure that the full range of the AD7143 for each sensor, an offset can be added to or subtracted from the voltage at the input of the converter. When the sensor is not being touched, the output of the converter should be midscale, around 32,768. Program the offset DACs so that the converter output is as close as possible to midscale ...

Page 15

... CDC modulator bias current by using the drop- down menus provided. The number of required sequencer stages depends on the sensors attached to the AD7143. The decimation rate is the factor by which the CDC output is oversampled by the AD7143. Figure 9. CDC Converter Dialog Box Rev Page EVAL-AD7143 ...

Page 16

... EVAL-AD7143 CALIBRATION ENGINE DIALOG BOX To access the calibration engine settings for each sequencer stage, click the block representing that stage in the Calibration Engine area of the block diagram (see Figure 6). The dialog boxes shown in this section are opened by clicking the block representing Sequencer Stage 0 in the calibration engine. ...

Page 17

... When the lower sensitivity setting is changed, the minimum threshold is recalculated, and the graph is redrawn with the new value. Figure 11. Sequencer Stage 0 Dialog Box, Initial Setup Tab Figure 12. Minimum Threshold Formula Rev Page EVAL-AD7143 CHANGING THE SENSITIVITY CHANGES THE THRESHOLD VALUE. AMBIENT VALUE. ...

Page 18

... EVAL-AD7143 The dialog box for the RAM Data tab on the left-hand side of the Calibration Engine dialog box is shown in Figure 13. This box shows the contents of the on-chip RAM used during the calculation of the maximum and minimum thresholds for Sequencer Stage 0. These values reside in memory on the ...

Page 19

... The bit that controls this function is located in the control register. block diagram, Selecting the SRC Disable check box disables SRC. SELECT THIS CHECK BOX TO DISABLE THE SRC OUTPUT. Figure 14. Excitation Source Dialog Box Rev Page EVAL-AD7143 ...

Page 20

... EVAL-AD7143 AMBIENT COMPENSATION DIALOG BOX Clicking Ambient Compensation in the diagram opens the Ambient Compensation dialog box, which is shown in Figure 15. This box provides access to all four CDC conversion control registers. These registers contain the global conversion controls for the AD7143. In the Stage Calibration Enable 0x01 register, Bit 0 to Bit 7 are calibration enable bits for Sequencer Stage 0 to Sequencer Stage 7 ...

Page 21

... INT polarity to active high. Setting this bit to 0, sets INT polarity to active low. Figure 16. Interrupt Configuration Registers Dialog Box Rev Page EVAL-AD7143 SELECT THESE CHECK BOXES TO ENABLE THE LOW LIMIT INTERRUPT FOR EACH SEQUENCER STAGE. SELECT THESE CHECK BOXES TO ENABLE THE HIGH LIMIT INTERRUPT FOR EACH SEQUENCER STAGE ...

Page 22

... EVAL-AD7143 POWER CONTROL DIALOG BOX By clicking Power Control in the block diagram of the AD7143, the dialog box shown in Figure 17 opens. This box shows the contents of the control register that relate to power control for the AD7143. To perform a software reset, click SW_RESET. This bit is self- clearing ...

Page 23

... Stage High Limit Interrupt 0x09 register indicates which, if any, sequencer stage has exceeded its upper threshold. The Stage Complete Limit Interrupt 0x0A register indicates which, if any, sequencer stage has triggered a conversion complete interrupt. Figure 18. CDC Status Dialog Box Rev Page EVAL-AD7143 ...

Page 24

... EVAL-AD7143 SETUP REGISTERS The Setup Registers dialog box in the block diagram of the AD7143 allows AD7143 register settings to be saved and loaded to and from a text file. These setup registers contain values to set up the calibration and proximity detection routines on-chip for each sequencer stage, as well as general-purpose setup values for the AD7143 ...

Page 25

... EVALUATION BOARD SCHEMATICS AND ARTWORK Figure 20. AD7143 Evaluation Board Schematic, USB Section Rev Page EVAL-AD7143 06583-020 ...

Page 26

... EVAL-AD7143 Figure 21. AD7143 Evaluation Board Schematic, AD7143 Section Rev Page 06583-021 ...

Page 27

... Figure 22. AD7143 Evaluation Board Silkscreen Figure 23. AD7143 Evaluation Board Component View Figure 24. AD7143 Evaluation Board Solder Side View Rev Page EVAL-AD7143 ...

Page 28

... EVAL-AD7143 ORDERING INFORMATION ORDERING GUIDE Model Description 1 EVAL-AD7143-1EBZ Evaluation Board Pb-free part. ©2007 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. EB06583-0-2/07(0) ESD CAUTION Rev Page ...