AD7606 IIO Application

Supported Hardware

Supported Devices:

• AD7606B

• AD7606C-16

• AD7606C-18

• AD7605-4

• AD7606-4

• AD7606-6

• AD7606

• AD7608

• AD7609

Supported Evaluation Boards:

• EVAL-AD7606B-FMCZ

• EVAL-AD7606CFMCZ

• EVAL-AD7605-4

• EVAL-AD7606-4

• EVAL-AD7606-6

• EVAL-AD7606

• EVAL-AD7608

• EVAL-AD7609

Supported Carrier Boards:

• SDP-K1 With Mbed

Introduction

This guide gives an overview of using the IIO firmware application with Analog Devices AD7606 Evaluation boards and SDP-K1 (or other compatible) MCU controller board, leveraging Mbed-OS as a primary software platform. This firmware application leverages the ADI developed IIO (Industrial Input Output) ecosystem to evaluate the AD7606 (IIO) device by providing device configuration and data capture support.

The interface used for communicating with PC based IIO clients is either Virtual Serial Or UART. IIO Firmware leverages the ADI created no-os and platform driver software layers to communicates with IIO device.

Note

This code has been developed and tested on the SDP-K1 Controller Board with Arduino headers. However, the same code can be used with minimal modifications on any Mbed enabled board which has Arduino Header support on it. To find out all supported Mbed boards, refer this link: https://os.mbed.com/platforms/

Useful Links

• Source Code: Precision Converters Firmware

• no-OS: Software drivers for systems without OS

• Keil Studio Web IDE/Compiler

• SDP-K1 on Mbed

• Linux Drivers

• HDL Source Code

Note

Linux and HDL are not used in emebdded IIO firmware projects but they may be of interest if you require Linux and/or FPGA support.

Hardware Connections

Jumper Settings

SDP-K1:

Connect the VIO_ADJUST jumper on the SDP-K1 board to 3.3V position to drive SDP-K1 GPIOs at 3.3V

EVAL-AD7606B-FMCZ:

Make below jumper settings on the AD7606B FMC board. For other boards, refer respective user manual for more details.

Jumper	Position	Purpose
JP1	A	Ignored in software mode
JP2	B	The unregulated external supply to the on-board LDOs is taken from the P4 terminal block connector (9V screw terminal)
JP3	A	The AD7606B is supplied with 3.3V VDRIVE from the ADP7118
JP4	A	Ignored in software mode.
JP5	A	Serial interface is selected.
JP6	B	Internal reference is enabled and selected. R1 must be unpopulated.
OS Switches (S1)	Default (Open)	Open by default. The OS pins are controlled and set in the firmware as logic high.

Communication Interface

Note

For data transmission to IIO clients, IIO firmware applications uses Virtual Serial Or UART as primary communication links. Firmware by default uses the Virtual Serial interface for higher speed data transmission as SDP-K1 MCU board and Mbed firmware supports both Virtual Serial and UART interface. If you target a different MCU board that does not support Virtual Serial, just set UART as communication link in the firmware (app_config.h file).

SDP-K1 is powered through USB connection from the computer. SDP-K1 MCU board acts as a serial device when connected to PC, which creates a serial ports to connect to IIO client application running on PC. The serial port assigned to a device can be seen through the device manager for windows-based OS as shown below:

Note

The serial port naming is used differently on different operating systems. For example, Linux uses terms such as dev/ttyUSB* and Mac uses terms such as dev/tty.USB*. Please check serial port naming for your selected OS.

Identifying Virtual Serial Port (Windows-OS):

To identify if serial port is virtual, right click on the port name and select ‘Properties’. Select ‘Events’ from menu option and check for below highlighted VIDs/PIDs and firmware name which is currently running on MCU.

SDP-K1 can support high speed Virtual Serial USB interface, so by default Virtual Serial is configured as default interface in the Mbed firmware. The interface can be set to Physical (UART) serial port by defining macro USE_PHY_COM_PORT in the app_config.h file.

/* Enable the UART/VirtualCOM port connection (default VCOM) */
//#define USE_PHY_COM_PORT           // Uncomment to select UART

Build Guide

Build Prerequisites

Prior to building a firmware project, it is required to set up an environment so that the build process may find the necessary tools (compiler, linker, SDK etc.). Use the following steps to prepare your environment for building firmware projects for respective platform.

Windows

Mbed

For Web/Online Build

• Visit Arm Keil website to create an user account for accessing the web based Keil Studio IDE.

• Open Keil Studio Web IDE with registered user account

For Make Build

• Clone Precision Converters Firmware repository with the –recursive flag (not needed if building with web IDE for Mbed platform):

git clone --recursive https://github.com/analogdevicesinc/precision-converters-firmware

• If however you’ve already cloned the repository without the –recursive flag, you may initialize all the submodules in an existing cloned repo with:

git submodule update --recursive --init

• Install Make in the root of ‘C’ drive without any spaces in the installation path. The path must be C:\GnuWin32\…. Add this path into the system environmental path variable (as shown in below screenshot).

• Install Git and add a path of C:\Program Files\Git\usr\bin\ directory into system environmental path variable (please verify your git installation path is correct).

• Install Mbed CLI 1 as per guide here.

• Install GNU Arm Embedded compiler (for the development, 9-2019-q4-major version is used) and add a path of GNU Arm Embedded Toolchain bin directory into the system environmental path variable (as shown in below screenshot).

• Configure the compiler location with Mbed CLI. This can be carried out by running the mbed config -G GCC_ARM_PATH <path-to-your-gcc-compiler> in Command Prompt. For example you can run mbed config -G GCC_ARM_PATH “C:\Program Files (x86)\GNU Tools ARM Embedded\9 2019-q4-major\bin” in command prompt. It will set mentioned compiler path to all the Mbed Projects.

  

STM32

For STM32 IDE based Build

• Install STM32CubeIDE

• Install STM32CubeMX

  

Building a project

Once the build enviornment is setup, follow the guide below to build your project and generate executable file (.bin/.hex)

Windows

Mbed

Build Using Web/Online IDE

• Clone the Precision Converters Firmware repository into Keil Studio using “File->clone…” menu.

  

• Once the project repository is imported, wait until all library dependencies are imported as shown in below screenshot. Now, open the ‘.medignore’ file present in the root directory of repository. Add comment syntax (two forward slashes) in front of the project name which you want to build. This will ignore all other projects and build only the comment syntax selected project.

  

• Select the target device (default used for development is SDP-K1) and click on ‘Clean build’ option to build the project. After a successful build a binary will be downloaded to your computer- store this on your drive. Drag and drop this binary to the USB drive hosted by your controller board to flash the MCU.

  

Note

If you intend to build different project, then modify the .medignore file in the root directory as mentioned in step2 and clean build project as mentioned in step3

Build Using Make

• Open Git bash and change current directory to project directory (eg. precision-converters-firmware/projects/ad4130_iio directory) which you want to build.

• Type make on the git bash command prompt to build a project.

• After successful build, binary file will be created into the Project_Name/build directory.

• If you want to clean build, type make reset on git bash command which deletes all generated build files for the given project.

Note

Default TARGET_BOARD is SDP_K1 and COMPILER is GCC_ARM. Current Make based build only support GCC_ARM Compiler.

• By default project is built for “SDP_K1” Board and “GCC_ARM” Compiler. If you want to build for other Mbed Board, For example If you want to build the project for “DISCO_F769NI” Board then run make TARGET_BOARD=DISCO_F769NI command in git bash command prompt. If you want to clean build, run make reset TARGET_BOARD=DISCO_F769NI command to delete the generated build files for the given project.

STM32

Build Using STM32 IDE

• Open the respective project directory by navigating into the “precision_converters_firmware/projects/” folder.

• In the “STM32” folder present within the project directory, double click and open the .ioc file present within.

  

• Click on the “Generate Code” option seen on the top right corner

  

• Upon successful generation of drivers for the selected MCU, the autogenerated files would be seen in the same directory where the .ioc file was present. Double click and open the “.project” file seen in the list of files

  

• After the project is loaded to the STM32CubeIDE, unfold the adxxxx_iio project seen in the project explorer, right click the “app” folder, select “Settings” under the “C/C++ Build” section on the left pane and un-check the “Exclude resources from build” checkbox. This would ensure that the project specific files are included by the build system

  

• In order to choose STM32 platform in the firmware, select the “ACTIVE_PLATFORM” as “STM32_PLATFORM” in the app_config.h from the respective project. Alternately , add compiler flag “ACTIVE_PLATFORM=value of STM32_PLATFORM in app_config.h” for selecting stm32 platform.

• Add compiler flags “-u _printf_float” to the project settings.

  

• Program by clicking on the “Run adxxxx_iio” option seen or by performing a copy->paste option of the .hex file seen in the STM32/Debug folder

  

Running a project

Once the firmware build is successful and binary file is generated, copy the generated binary into USB drive hosted by your MCU board (e.g. USB drive hosted by SDP-K1 board on windows). This will flash the binary file into MCU present on the controller board. Programming might vary based on the tools used for building a project. The ‘Project Build’ section above talks about this exception at the end of all build steps.

Using the IIO Ecosystem

IIO (Industrial Input/Output) is a flexible ecosystem that allows various client tools to communicate with IIO device to configure the device, capture device data, generate waveforms, access registers, etc. Below diagram demonstrates the high level architecture of IIO ecosystem.

https://wiki.analog.com/resources/tools-software/linux-software/libiio

IIO Tools:

IIO Oscilloscope ADI IIO Oscilloscope is a cross platform GUI application, which demonstrates how to interface different evaluation boards within an IIO ecosystem. It supports raw data capture, FFT analysis, DMM measurement, device configuration, register read/write and data streaming.

pyadi-iio: Python interfaces Analog Devices python interfaces for hardware with Industrial I/O drivers. It provides python based scripts for raw data capture, device configuration and register read/write.

ACE ADI’s “Analysis, Control, Evaluation” (ACE) is a desktop software application which allows the evaluation and control of multiple evaluation systems.

Precision Converters MATLAB Toolbox Toolbox created by ADI to be used with MATLAB and Simulink with ADI Precision products.

IIO Command Line Command line interface for accessing IIO device parameters.

Pocketlab ADI Pocketlab is a display based GUI client. It supports raw data capture, FFT analysis, DMM measurement, device configuration, register read/write.

Note

These are the general evaluation and prototyping tools for Precision Converters but not all converters are supported. In some cases these tools provide generic IIO support (e.g. ACE, IIO Oscilloscope) and can provide basic functionality with any IIO based system. In other cases if a part is not currently supported, it is possible to add support for converters that you need due to the open source nature of the tools.

Calibrating AD7606B/C Devices

ADC Gain Calibration:

ADC gain calibration can be done in 3 easy steps as mentioned in below diagram. The gain calibration needs to be done for selected gain filter register as specified in the datasheet (refer ‘System Gain Calibration’ section from the AD7606B/C datasheet). The gain calibration can be done for each channel depending upon the filter resistor placed in series with each channel analog input.

References: Source file: iio_ad7606.c, Function: get_chn_calibrate_adc_gain()

ADC Offset Calibration:

ADC offset calibration should only be done when ADC input is 0V. The purpose is to reduce any offset error from the input when analog input is at 0V level. The ADC offset calibration can be done for each input channel. To perform ADC offset calibration, select the ‘calibrate_adc_offset’ attribute. It should automatically perform the calibration. Also, if ‘Read’ button is pressed, the calibration should happen one more time.

References: Source file: iio_ad7606.c, Function: get_chn_calibrate_adc_offset()

Open Circuit Detection on AD7606B Device

AD7606B device provides an open circuit detection feature for detecting the open circuit on each analog input channel of ADC. There are 2 modes to detect open circuit on analog inputs (Refer AD7606B datasheet for more details):

• Manual Mode

• Auto Mode

Manual Mode Open Circuit Detect:

The manual open circuit detection needs ‘Rpd’ to be placed at analog input as shown in figure below. The firmware is written to perform the open circuit detection @50Kohm of Rpd value. The common mode change threshold has been defined as 15 ADC count in the firmware at above specified configurations (as specified in the datasheet).

References: Source file: iio_ad7606.c, Function: get_chn_open_circuit_detect_manual()

Auto Mode Open Circuit Detect:

The auto open circuit detection on each individual ADC channel can be done by performing 3 easy steps mentioned in below screenshot.

References: Source file: iio_ad7606.c, Function: get_chn_open_circuit_detect_auto()

Diagnostic Multiplexer on AD7606B/C Devices

Using diagnostic multiplexer on AD7606B/C devices, the internal analog inputs can be sampled to provide a diagnostic voltages and parameters on IIO client application such as reference voltage (vref), DLO voltage (ALDO/DLDO), temperature and drive voltage (vdrive).

Note: The diagnostic mux control must operate when input range is +/-10V

IIO Firmware Structure

Below diagram illustrates the architecture of Precision Converters IIO firmware applications.

Support

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