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基于Nios驅(qū)動的AD7685 BeMicro FPGA方案

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資料介紹

This version (26 Jan 2021 01:27) was approved by Robin Getz.The Previously approved version (28 Sep 2012 09:16) is available.

BeMicro FPGA Project for AD7685 with Nios driver

Supported Devices

AD7685

Evaluation Boards

EVAL-AD7685SDZ

Overview

This lab presents the steps to setup an environment for using the EVAL-AD7685SDZ evaluation board together with the BeMicro SDK USB stick and the Nios II Embedded Development Suite (EDS). Below is presented a picture of the EVAL-AD7685SDZ Evaluation Board with the BeMicro SDK Platform.

For component evaluation and performance purposes, as opposed to quick prototyping, the user is directed to use the part evaluation setup. This consists of:

1. A controller board like the SDP-B ( EVAL-SDP-CS1Z)
2. The component SDP compatible product evaluation board
3. Corresponding PC software ( shipped with the product evaluation board)

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.

28 Sep 2012 09:00 · Adrian Costina

Below is presented a picture of SDP-B Controller Board with the EVAL-AD7685SDZ Evaluation Board.

The EVAL-AD7685SDZ 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 AD7685 circuits and reduce design time.

The AD7685 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 an analog input IN+ between 0 V to REF with respect to a ground sense IN-. The reference voltage, REF, is applied externally and can be set up to the supply voltage.

More information

AD7685 Product Info - pricing, samples, datasheet
EVAL-AD7685SDZ evaluation board user guide
BeMicro SDK
Nios II Embedded Development Suite (EDS)

Getting Started

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.

Hardware Items

Below is presented the list of required hardware items:

Arrow Electronics BeMicro SDK FPGA-based MCU Evaluation Board
BeMicro SDK/SDP Interposer adapter board
EVAL-AD7685SDZ evaluation board
Intel Pentium III or compatible Windows PC, running at 866MHz or faster, with a minimum of 512MB of system memory

Software Tools

Below is presented the list of required software tools:

Quartus II Web Edition design software v12.0sp2
Nios II EDS v12.0sp2

The Quartus II design software and the Nios II EDS is available via the Altera Complete Design Suite DVD or by downloading from the web.

Downloads

Lab Design Files

Extract the Lab Files

Create a folder called “ADIEvalBoardLab” on your PC and extract the ad7685_evalboardlab.zip archive to this folder. Make sure that there are NO SPACES in the directory path. After extracting the archive the following folders should be present in the ADIEvalBoardLab folder: FPGA, Hdl Software, DataCapture, NiosCpu.

Folder	Description
FPGA	Contains all the files necessary to program the BeMicro FPGA board in order to run the evaluation project. By executing the script program_fpga.bat the FPGA will be programmed with the evaluation project. New NIOS II applications can be created using the files from this folder. The ip subfolder contains the AD7685 NIOS II peripheral's source code.
Hdl	Contains the source files for the AD7685 HDL driver: - The doc subfolder contains a brief documentation for the driver. - The src subfolder contains the HDL source files. - The tb folder contains the sources of the driver's testbench.
NiosCpu	Contains the Quartus evaluation project source files . The ip subfolder contains the AD7685 Nios2 peripheral source code.
Software	Contains the source files of the Nios2 SBT evaluation project.
DataCapture	Contains the script files used for data acquisition

Install the USB-Blaster Device Driver

After the Quartus II and Nios II software packages are installed, you can plug the BeMicro SDK board into your USB port. Your Windows PC will find the new hardware and try to install the driver.

Since Windows cannot locate the driver for the device the automatic installation will fail and the driver has to be installed manually. In the Device Manager right click on the USB-Blaster device and select Update Driver Software.

In the next dialog box select the option Browse my computer for driver software. A new dialog will open where it is possible to point to the driver’s location. Set the location to altera//quartus/drivers/usb-blaster and press Next.

If Windows presents you with a message that the drivers have not passed Windows Logo testing, please click “Install this driver software anyway”. Upon installation completion a message will be displayed to inform that the installation is finished.

15 Sep 2011 15:23

AD7685 Evaluation Project Overview

The evaluation project contains all the source files needed to build a system that can be used to configure the AD7685 and capture data from it. The system consists of a Nios II softcore processor that is implemented in the FPGA found on the BeMicro board and a PC application. The softcore controls the communication with the Device Under Test (DUT) and the data capture process. The captured data is saved into the onchip RAM of the BeMicro board and aftwerwards it is read by the PC application and saved into a comma separated values (.csv) file that can be used for further data analysis.

The following components are implemented in the FPGA design:

Name	Address	IRQ
CPU	0x00000800	-
JTAG UART	0x00000090	0
uC-Probe UART	0x000000A0	1
EPCS FLASH CONTROLLER	0x00001800	2
OnChip RAM	0x00010000	-
LED GPIO	0x00000100	-
GPIO	0x00002080	-
CTRL GPIO	0x000020A0	-
SYS ID	0x00000040	-
TIMER	0x00000060	3
AVALON MASTER	-	-
Main PLL	0x00000080	-
AD7685 PERIPHERAL	0x00000120	-
Table 1 System components

The Nios II processor contains a peripheral that implements the communication protocol with the DUT. The peripheral is divided into three logical modules: a module which implements the interface with the Avalon bus and the communication with the onchip RAM, a module which implements an Avalon master interface which is used to write data directly in the onchip RAM and a module which is the actual driver of the DUT. The driver can also be used as standalone in FPGA designs which do not contain a softcore. Following is presented a block diagram of the HDL driver and a description of the driver's interface signals.

Table 2 describes the ports of the AD7685 HDL driver.

Port	Direction	Width	Description
Clock and reset ports
FPGA_CLK_I	IN	1	Main clock input.
RESET_I	IN	1	Active low reset signal.
ADC_CLK_I	IN	1	Clock to be sent to the ADC during the conversion process.
IP control and data ports
DATA_O	OUT	16	Outputs the data read from the ADC.
DATA_RD_READY_O	OUT	1	Active high signal to indicate the status of a read operation from the AD7685. The IP continuously reads the conversion results from the ADC and outputs them on the DATA_O bus. When this signal is high data can be read from the DATA_O bus.
AD7685 control and data ports
ADC_SDO	IN	1	ADC Serial Data Output. The conversion result is output on this pin. It is synchronized to SCLK
ADC_SDI	IN	1	ADC Serial Data Input. This pin is currently not used in the design.
ADC_SCLK_O	OUT	1	ADC Serial Data Clock Input. When the part is selected, the conversion result is shifted out by this clock.
ADC_CNVST_O	OUT	1	ADC Convert Input. This input has multiple functions. On its leading edge, it initiates the conversions and selects the interface mode of the part, chain, or CS mode. In CS mode, it enables the SDO pin when low. In chain mode, the data should be read when CNV is high.
Table 2 AD7685 driver ports description

The follwing figure presents the timing diagram for the read operations from the AD7685 driver.

Table 3 describes the ports of the Avalon peripheral:

Port	Direction	Width	Description
Clock and reset ports
CLK_I	IN	1	Main clock input
RESET_I	IN	1	System reset
ADC_CLK_I	IN	1	ADC clock
Avalon Slave Interface
AVALON_WRITEDATA_I	IN	32	Slave write data bus
AVALON_WRITE_I	IN	1	Slave write data request
AVALON_READ_I	IN	1	Slave read data request
AVALON_ADDRESS_I	IN	2	Slave address bus
AVALON_READDATA_O	OUT	32	Slave read data bus
Avalon Master Interface
AVALON_MASTER_WAITREQUEST	IN	1	Master wait request signal
AVALON_MASTER_ADDRESS_O	OUT	32	Master address bus
AVALON_MASTER_BYTEENABLE_O	OUT	4	Master byte enable signals
AVALON_MASTER_WRITEDATA_O	OUT	32	Master write data bus
External connectors
ADC_SDO	IN	1	ADC Serial Data Output. The conversion result is output on this pin. It is synchronized to SCLK
ADC_SDI	IN	1	ADC Serial Data Input. This pin is currently not used in the design.
ADC_SCLK_O	OUT	1	ADC Serial Data Clock Input. When the part is selected, the conversion result is shifted out by this clock.
ADC_CNVST_O	OUT	1	ADC Convert Input. This input has multiple functions. On its leading edge, it initiates the conversions and selects the interface mode of the part, chain, or CS mode. In CS mode, it enables the SDO pin when low. In chain mode, the data should be read when CNV is high.
Table 3 Avalon peripheral ports description

Table 4 describes the registers of the Avalon peripheral:

Name	Offset	Width	Access	Description
CONTROL_REGISTER	0	32	RW	Bit 0 is used to start data acquisition Bit 1 is used to initiate software reset of the core Bit 2 is used to configure the Avalon write master core to write data to the same location Bit 3 is used to write data to the AD7685 evaluation board
ACQ_COUNT_REGISTER	1	32	RW	Register used to configure the number of samples to be acquired when acquisition is started
BASE_REGISTER	2	32	RW	Register used to configure the base address of the memory location where the acquired data is to be written
STATUS_REGISTER	3	32	R	Bit 0 is used to signal that the acquisition is complete Bit 1 is used to signal that the internal memory buffer has been overflown Bit 2 is used to signal that the user has performed a read of an unavailable register
Table 4 Avalon peripheral registers description

Quick Evaluation

The next sections of this lab present all the steps needed to create a fully functional project that can be used for evaluating the operation of the ADI platform. It is possible to skip these steps and load into the FPGA an image that contains a fully functional system.The first step of the quick evaluation process is to program the FPGA with the image provided in the lab files. Before the image can be loaded the Quartus II Web Edition tool or the Quartus II Programmer must be installed on your computer. To load the FPGA image run the program_fpga.bat batch file located in the ADIEvalBoardLab/FPGA folder. After the image was loaded the system must be reset. Now the FPGA contains a fully functional system and it is possible to skip directly to the Demonstration Project User Interface section of this lab.

03 Sep 2012 17:42 · Adrian Costina

NIOS II Software Design

This section presents the steps for developing a software application that will run on the BeMicroSDK system and will be used for controlling and monitoring the operation of the ADI evaluation board.

Create a new project using the NIOS II Software Build Tools for Eclipse

Launch the Nios II SBT from the Start → All Programs → Altera 12.0sp2→ Nios II EDS 12.0sp2 → Nios II 12.0sp2 Software Build Tools for Eclipse (SBT).

NOTE: Windows 7 users will need to right-click and select Run as administrator. Another method is to right-click and select Properties and click on the Compatibility tab and select the Run This Program As An Administrator checkbox, which will make this a permanent change.

1. Initialize Eclipse workspace

When Eclipse first launches, a dialog box appears asking what directory it should use for its workspace. It is useful to have a separate Eclipse workspace associated with each hardware project that is created in SOPC Builder. Browse to the ADIEvalBoardLab directory and click Make New Folder to create a folder for the software project. Name the new folder “eclipse_workspace”. After selecting the workspace directory, click OK and Eclipse will launch and the workbench will appear in the Nios II perspective.

2. Create a new software project in the SBT

Select File → New → Nios II Application and BSP from Template.

Click the Browse button in the SOPC Information File Name dialog box.
Select the uC.sopcinfo file located in the ADIEvalBoardLab/FPGA directory.
Set the name of the Application project to “ADIEvalBoard”.
Select the Blank Project template under Project template.
Click the Finish button.

The tool will create two new software project directories. Each Nios II application has 2 project directories in the Eclipse workspace.

The application software project itself - this where the application lives.
The second is the Board Support Package (BSP) project associated with the main application software project. This project will build the system library drivers for the specific SOPC system. This project inherits the name from the main software project and appends “_bsp” to that.

Since you chose the blank project template, there are no source files in the application project directory at this time. The BSP contains a directory of software drivers as well as a system.h header file, system initialization source code and other software infrastructure.

Configure the Board Support Package

Configure the board support package to specify the properties of this software system by using the BSP Editor tool. These properties include what interface should be used for stdio and stderr messages, the memory in which stack and heap should be allocated and whether an operating system or network stack should be included with this BSP.
Right click on the ADIEvalBoard_bsp project and select Nios II → BSP Editor… from the right-click menu.

The software project provided in this lab does not make use of an operating system. All stdout, stdin and stderr messages will be directed to the jtag_uart.

Select the Common settings view. In the Common settings view, change the following settings:
- Select the jtag_uart for stdin, stdout and stderr messages. Note that you have more than one choice.
- Select none for the sys_clk_timer and timestamp_timer.

Select File → Save to save the board support package configuration to the settings.bsp file.
Click the Generate button to update the BSP.
When the generate has completed, select File → Exit to close the BSP Editor.

Configure BSP Project Build Properties

In addition to the board support package settings configured using the BSP Editor, there are other compilation settings managed by the Eclipse environment such as compiler flags and optimization level.

Right click on the ADIEvalBoard_bsp software project and select Properties from the right-click menu.
On the left-hand menu, select Nios II BSP Properties.
During compilation, the code may have various levels of optimization which is a tradeoff between code size and performance. Change the Optimization level setting to Level 2
Since our software does not make use of C++, uncheck Support C++.
Check the Reduced device drivers option
Check the Small C library option
Press Apply and OK to regenerate the BSP and close the Properties window.

Add source code to the project

In Windows Explorer locate the project directory which contains a directory called Software. In Windows Explorer select all the files and directories from the Software folder and drag and drop them into the Eclipse software project ADIEvalBoard.

Select all the files and folders and drag them over the ADIEvalBoard project in the SBT window and drop the files onto the project folder.

A dialog box will appear to select the desired operation. Select the option Copy files and folders and press OK.

This should cause the source files to be physically copied into the file system location of the software project directory and register these source files within the Eclipse workspace so that they appear in the Project Explorer file listing.

Configure Application Project Build Properties

Just as you configured the optimization level for the BSP project, you should set the optimization level for the application software project ADIEvalBoard as well.

Right click on the ADIEvalBoard software project and select Properties from the right-click menu.
On the left-hand menu, select the Nios II Application Properties tab
Change the Optimization level setting to Level 2.
Press Apply and OK to save the changes.

Compile, Download and Run the Software Project

1. Build the Application and BSP Projects

Right click the ADIEvalBoard_bsp software project and choose Build Project to build the board support package.
When that build completes, right click the ADIEvalBoard application software project and choose Build Project to build the Nios II application.

These 2 steps will compile and build the associated board support package, then the actual application software project itself. The result of the compilation process will be an Executable and Linked Format (.elf) file for the application, the ADIEvalBoard.elf file.

2. Verify the Board Connection

The BeMicroSDK hardware is designed with a System ID peripheral. This peripheral is assigned a unique value based on when the hardware design was last modified in the SOPC Builder tool. SOPC Builder also places this information in the .sopcinfo hardware description file. The BSP is built based on the information in the .sopcinfo file.

Select the ADIEvalBoard application software project.
Select Run → Run Configurations…
Select the Nios II Hardware configuration type.
Press the New button to create a new configuration.
Change the configuration name to BeMicroSDK and click Apply.
On the Target Connection tab, press the Refresh Connections button. You may need to expand the window or scroll to the right to see this button.
Select the jtag_uart as the Byte Stream Device for stdio.
Check the Ignore mismatched system ID option.
Check the Ignore mismatched system timestamp option.

3. Run the Software Project on the Target

To run the software project on the Nios II processor:

Press the Run button in the Run Configurations window.

This will re-build the software project to create an up–to-date executable and then download the code into memory on the BeMicroSDK hardware. The debugger resets the Nios II processor, and it executes the downloaded code. Note that the code is verified in memory before it is executed.

The code size and start address might be different than the ones displayed in the above screenshot.

04 Sep 2012 09:08 · Adrian Costina

Demonstration Project User Interface

* Execute data_capture.bat script. At this point 16 Kbyte of data will be acquired from the ADC and saved into the BeMicro SDK memory. The data stored in the BeMicro SDK memory is transfered to the PC. After the data is transferred to the PC it is converted to 16 bit values.

The data captured from the ADC is saved into a comma separated values (.csv) file named Acquisition.csv, located in the same folder as the data_capture.bat file.
The data capture status is also displayed in the opened command window as shown in the figure below.

A new acquisition can be started by executing the data_capture.bat script.

Note: If several consecutive data acquisitions are performed the captured data is appended to the Acquisition.csv file.

Troubleshooting

In case there is a communication problem with the board the follwing actions can be perfomed in order to try to fix the issues:

Check that the evaluation board is powered.
Check that the USB connection cable is properly connected to the device and to the computer and that the USB Blaster Device Driver driver is installed correctly. If the driver is not correctly installed perform the steps described in the Getting Started → Install te USB-Blaster Device Driver section.

04 Sep 2012 09:24 · Adrian Costina