This document presents the steps to setup an environment for using the EVAL-AD7687SDZ evaluation board together with the Xilinx KC705 FPGA board and the Xilinx Embedded Development Kit (EDK). Below is presented a picture of the EVAL-AD7687SDZ Evaluation Board with the Xilinx KC705 board.
For component evaluation and performance purposes, as opposed to quick prototyping, the user is directed to use the part evaluation setup. This consists of:
The SDP-B controller board is part of Analog Devices System Demonstration Platform (SDP). It provides a high speed USB 2.0 connection from the PC to the component evaluation board. The PC runs the evaluation software. Each evaluation board, which is an SDP compatible daughter board, includes the necessary installation file required for performance testing.
Note: it is expected that the analog performance on the two platforms may differ.
Below is presented a picture of SDP-B Controller Board with the EVAL-AD7687SDZ Evaluation Board.
The AD7687 is a 16-bit, charge redistribution, successive approximation, analog-to-digital converter (ADC) that operates from a single power supply, VDD, between 2.3 V to 5.5 V. It contains a low power, high speed, 16-bit sampling ADC with no missing codes, an internal conversion clock, and a versatile serial interface port. The part also contains a low noise, wide bandwidth, short aperture delay track-and-hold circuit. On the CNV rising edge, it samples the voltage difference between IN+ and IN− pins. The voltages on these pins usually swing in opposite phase between 0 V to REF. The reference voltage, REF, is applied externally and can be set up to the supply voltage. Its power scales linearly with throughput.
The EVAL-AD7687SDZ evaluation board is a member of a growing number of boards available for the SDP. It was designed to help customers evaluate performance or quickly prototype new AD7687 circuits and reduce design time. When using this evaluation board with the SDP board or Xilinx KC705 board, apply +7.5V as +Vs, a voltage between -2V and -5V as -Vs and +2.5V as VDD.
The first objective is to ensure that you have all of the items needed and to install the software tools so that you are ready to create and run the evaluation project.
The following table presents a short description the reference design archive contents.
|Bit||Contains the KC705 configuration file that can be used to program the system for quick evaluation.|
|DataCapture||Contains the script used to read data from the ADC and save it into a file on the PC.|
|Hdl||Contains the HDL driver for the AD7687 ADC.|
|Microblaze||Contains the EDK 13.2 project for the Microblaze softcore that will be implemented in the KC705 FPGA.|
|Software||Contains the source files of the software project that will be run by the Microblaze processor.|
Before connecting the ADI evaluation board to the Xilinx KC705 make sure that the VADJ_FPGA voltage of the KC705 is set to 3.3V. For more details on how to change the setting for VADJ_FPGA visit the Xilinx KC705 product page.
At this point everything is set up and it is possible to start the evaluation of the ADI hardware. To capture data from the ADC run the data_capture.bat script located in the DataCapture folder from the reference design .zip file. Every time the script is run a new batch of 8192 samples are read from the ADC at the ADC's maximum sampling rate and saved into the Acquisition.csv file located in the same folder as the data capture script. On the UART terminal messages will be displayed to show the status of the program running on the FPGA as shown in the picture below.
The first time the data capture script is run it is possible that an error will occur while the script is trying to connect to the system. Just run the script again and the error shouldn't appear anymore.