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This document presents the steps to setup an environment for using the EVAL-AD5235SDZ evaluation board together with the Xilinx KC705 FPGA board, the Xilinx Embedded Development Kit (EDK) and the Micrium µC-Probe run-time monitoring tool. Below is presented a picture of the EVAL-AD5235SDZ 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-AD5235SDZ Evaluation Board.
The EVAL-AD5235SDZ evaluation board is a member of a growing number of boards available for the SDP. Designed to help customers evaluate performance or quickly prototype new AD5235 circuits and reduce design time, the EVAL-AD5235SDZ evaluation board can operate in single-supply and dual-supply mode and incorporates an internal power supply powered from the USB.
The AD5235 is a dual-channel, 1024-position, nonvolatile memory digital potentiometer. With versatile programmability, the AD5235 allows multiple modes of operation, including read/write access in the RDAC and EEMEM registers, increment/decrement of resistance, resistance changes in ±6 dB scales, wiper setting read-back, and extra EEMEM for storing user-defined information, such as memory data for other components or a lookup table. The AD5235 supports dual-supply ±2.25 V to ±2.75 V operation and single-supply 2.7 V to 5.5 V operation, making the device suited for battery-powered applications and many other applications. In addition, the AD5235 uses a versatile SPI-compatible serial interface, allowing speeds of up to 50 MHz.
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.|
|Microblaze||Contains the EDK 13.4 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.|
|uCProbeInterface||Contains the uCProbe interface and the .elf symbols file used by uC-Probe to access data from the Microbalze memory.|
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 through the controls in the uC-Probe application provided in the reference design.
Launch uC-Probe from the Start → All Programs → Micrium → uC-Probe.
Select uC-Probe options.
Set target board communication protocol as RS-232
Setup RS-232 communication settings
The following figure presents the uC-Probe interface that can be used for monitoring and controlling the operation of the EVAL-AD5235SDZ evaluation board.
Section A is used to activate the board and monitor activity. The communication with the board is activated / deactivated by toggling the ON/OFF switch. The Activity LED turns green when the communication is active. If the ON/OFF switch is set to ON and the Activity LED is BLACK it means that there is a communication problem with the board. See the Troubleshooting section for indications on how to fix the communication problems.
Section B is used to send commands specific for the two RDAC channels available in the AD5235. Toggling to On the switches under a specific RDAC will send the command only to that RDAC. The following commands can be sent to the two RDAC channels individually:
Below the individual command options there is a set of generic switches which are used to send commands to both RDACs simultaneously. The following commands can be sent simultaneously to both RDACs:
Section C is used to send generic commands to the AD5235. The command list is available in table “Command Operation Truth Table” from the AD5235 datasheet . The request values will be updated based on the switch selections and displayed in the Request numeric boxes. The command is sent by toggling the Send Command switch to On. After the command a NOP will be sent on and the values from the SDO will be displayed in the Response numeric boxes.
Section D is used for setting the values for Write requests both for RDAC wiper writes and memory writes. In case of RDAC writes, the Address value is not used. In case of memory writes, the Address value is used to select the memory location. It is recommended to use the first slider for values that are stored in user memory locations and the second slider for values that are written in the RDAC wiper or RDAC memory location EEMEM0 and EEMEM1.
Section E is used to toggle the hardware pins. The functionality of the pins is described in the AD5235 datasheet , table “Pin Function Descriptions”. When the Write Protect switch is sent to On it isn’t possible to write to the memory nor change the RDAC values. Exceptions are the Restore/Reset function and toggling the \PR switch. In all cases the RDACs wipers will be reloaded with the values from the memory.
Section F displays the values stored in the EEPROM memories and the tolerance value. The displayed values are updated by toggling the Read switch to On. The Write switch controls the writing of the value specified by the slider Value for User Write to the memory address specified by the slider Address for EEMEM Write from Section D.
In case there is a communication problem with the board the follwing actions can be perfomed in order to try to fix the issues: