TDS02 - Training Digital Signal Processing 02

© Harry Broeders - Hogeschool Rotterdam.

This page is meant for student of the minor Embedded Systems at Rotterdam University or anyone who wants to experiment with digital signal processing using the CC3200AUDBOOST Audio BoosterPack from Texas Instruments (shown on the left) in combination with their CC3220S LaunchPad development board (shown on the right). This introduction describes how to install the proper software to experiment with these boards. The two most important components on these boards are the CC3220S SimpleLink™ Wi-Fi® Wireless Microcontroller Unit and the TLV320AIC3254 Codec (coder-decoder). The CC3220S System-on-Chip (SoC) is a single-chip with two separate execution environments: an user application dedicated ARM® Cortex®-M4 MCU and a network processor MCU. The TLV320AIC3254 is a 20-bit stereo audio codec with embedded miniDSP which can operate with a sample rate of up to 192 ksps (kilo samples per second) and is optimized for low-power operation. The audio quality is higher than CD quality which uses 16-bits with a sample rate of 44.1 ksps.

Obtain hard- and software

Students which follow the minor Embedded Systems at Rotterdam University may buy the boards shown above at the shop at EAS. To prevent damaging the boards by Electro Static Discharge (ESD) you have to observe the following precautions while handling the board:

• Ground yourself, preferably by using a wrist-strap.
• Always use a shielded bag if you need to transport the boards.

There are four programs which we will use in combination with these boards:

• Tera Term.
  A terminal emulator is needed because a lot of TI's demo programs use a (virtual) terminal connection to report statuses and errors. Tera Term was chosen because it recognizes which (virtual) serial ports are available. TI also uses this terminal emulator in its tutorials.
• UniFlash.
  This program is used to program the flash memory on the CC3220S LAUNCHXL board.
• Soundcard Oscilloscope.
  In the lab you can use a normal oscilloscope but at home you can use this program to generate and measure signals. You can also use this this program to generate frequency response graphs.
• Code Composer Studio (CCS).
  This Integrated Development Environment (IDE) will be used to develop software for the CC3220S.
• MATLAB.

  You will use MATLAB to design your digital filters.

You can choose to work on your own laptop or on a PC avaiable in the lab.

• If you work on your own PC, you have to install the software as explained in the following two paragraphs.
• If you work on a PC in the lab, you can find all programs in the Liquit Workspace. As an example, we explain here how you can use the program Tera Term. Start Liquit Workspace and look for Tera Term in the Catalog.

  

  Click your right mouse button and click Request. The program will now be available in the Liquit Workspace.

  

  You can start the program by double clicking the icon. You now have to start Code Composer Studio from Liquit so this program including all drivers will be installed. You can skip the next three paragraphs and continue here.

Install Tera Term, UniFlash and Soundcard Oscilloscope

Tera Term can be downloaded from https://osdn.net/projects/ttssh2/releases/.

UniFlash can be downloaded from http://www.ti.com/tool/download/UNIFLASH.

Soundcard Oscilloscope can be downloaded from zeitnitz.eu/scms/scope_en.

The installation of these programs needs no further explanation.

Install MATLAB

You can find the instructions to install MATLAB on your own PC in the direcory \\artemis03\STUD02\Opleiding\Elektrotechniek\2019-2020\Minor Embedded Systems\TDS02\Software on the students network of Rotterdam University.

Install Code Composer Studio

CCS can be downloaded from http://processors.wiki.ti.com/index.php/Download_CCS.

After accepting the license and choosing the install directory, you need to select the product families to install. You have to select SimpleLink™ Wi-Fi® CC32xx Wireless MCUs.

Press Next and then press Finish.

The installation of CCS9 needs no further explanation. This tutorial assumes that CCS9 is installed in its default directory C:\ti\ccsv9.

Run the out of the box application on the CC3220S LAUNCHXL board

The CC3220S LAUNCHXL board comes with an out of the box application installed in its flash memory. We start by running this application. Connect your board with the PC using an USB cable. Now start Tera Term.

Select Serial and select the XDS110 Class Application/User UART. This can be a different (virtual) COM port as shown below.

Choose Setup, Serial port... from the menu.

Adjust the Baud rate as shown below.

Now reset the CC3220S LAUNCHXL board by pressing the reset button which is located next to the USB connector.

If all goes well, the output shown below, will be displayed in Tera Term.

.

The out of the box application has started and some properties of the system are reported (e.g. the MAC address). The board is now waiting to be provisioned. In telecommunication, provisioning involves the process of preparing a network node to allow it to provide services to its users. The board supports two methods for provisioning AP + SC:

• Access Point (AP) - During AP provisioning, an unprovisioned Wi-Fi device temporarily operates as an AP. This allows a device such as a smartphone or tablet to connect to it over Wi-Fi and transmit the network information for the desired network connection.
• SmartConfig (SC) - SmartConfig is a TI proprietary provisioning method that uses a smartphone or tablet to broadcast network credentials to a TI Wi-Fi device.

You can now use your smartphone to connect to connect to the access point named mysimplelink-XXXXXX, where XXXXX are the last 6 (hexadecimal) digits from your MAC address. When your smartphone is connected to this access point you can open the website which is embedded in the out of the box application running on the CC3220S LAUNCHXL board. Just type the IP address 10.123.45.1 into the address bar of your favorite browser. You should be able to switch the red led on and off and to see the output of the accelerometer.

If you can see something similar to the figure above, you know that your board is working properly. It is now time to remove the out of the box application from the board's flash memory. Because otherwise we will have a lot of Wi-Fi access points in the lab which will interfere with the school's Wi-Fi network. You can always reinstall the out of the box application later.

Replace the out of the box application with a simple blinking led application

The code for the blinking led application is contained in a zip file which you can download here: images/knipper_groene_led_180512203400.zip. Download this file to your PC.

Open the UniFlash program and connect your CC3220S LAUNCHXL board to the PC. If all goes well UniFlash will recognize your board and you can press Start.

Now click on Manage Projects.

Click on the Import Project from ZIP file icon and select the file knipper_groene_led_180512203400.zip that you have downloaded earlier.

Select the project knipper_groene_led and click on the Open Selected Project icon.

Now click the Connect button.

Click the Burn button.

Finally, click on the Connect, Create and Program Image button.

The blinking led application is now programmed into the flash memory on theCC3220S LAUNCHXL board. After programming this application will start and, if all went well, the green led will blink. Now every time you reset the board this blinking led application will run. No Wi-Fi access point will be created by the board anymore.

Warnings!

• If you use Code Composer Studio (CCS) in the lab do not update the software! Because you don't have the necessary access rights CCS will refuse to start after the 'update'.
• If you start CCS in the lab for the first time, a pop-up window tells you that a Workspace will be created on the C-drive. It is more convenient to place your Workspace on your H-drive.

Install the SimpleLink CC32XX SDK (Software Development Kit) using CCS.

Open Code Composer Studio and choose View, Resource Explorer. Scroll down to find SimpleLink CC32XX SDK. Click on Download and install.

Check the SimpleLink Academy option.

Recompile the driverlib

To properly debug programs which use the driverlib (included in the SimpleLink SDK), the driverlib must be recompiled.

Choose Project, Import CCS projects... from the menu.

Click the Browse button and select the directory where the latest version of the simplelink_cc32xx_sdk has been installed: C:\ti\simplelink_cc32xx_sdk_3_20_00_06\source\ti\devices\cc32xx.

Click Select Folder.

Click Finish.

Choose Project, Build Project from the menu.

Wait until the message **** Build Finished **** appears in the Console window.

Connect the C3200AUDBOOST Audio BoosterPack with the CC3220S LAUNCHXL board

Now it is time to mount the C3200AUDBOOST Audio BoosterPack on top of the CC3220S LAUNCHXL board. The 2x10 pin Launchpad headers (P1, P2, P3, P4) connect the CC3200AUDBOOST board to the CC3220S LAUNCHXL. The headers provide the necessary interface to power up the audio boosterpack and access the I²C and I²S lines on the CC3220S LAUNCHXL board. While connecting to the CC3220S LAUNCHXL, ensure that the white 3V3 marker on the CC3220S LAUNCHXL board matches with the white triangle on the CC3200AUDBOOST boosterpack.

Run our demo program

The code and project files for the demo program are contained in a zip file which you can download here: line_in_2_line_out/line_in_2_line_out.zip. Download this file to your PC.

Start Code Composer Studio and choose a workspace directory. In this tutorial the workspace directory C:\workspace_v9\CC3220S is used. Choose Project, Import CCS Projects... from the menu.

Choose the Select archive file option and press Browse... Now select the file line_in_2_line_out.zip which you downloaded earlier and press Finish.

Now connect your board to the PC and press the debug button . The debugger will stop the program when the function main is entered.

Press the resume button .

The demo program will now copy the signals (left and right) on the line input to the line output. You can use a signal generator and an oscilloscope to test the program. The input signal should be about 1 V_pp. Take care to connect the output signal of the signal generator to the line input of your board. Connecting two outputs together can damage your board. Alternatively you can use your smartphone and headset to test the program.

Inconvenience while debugging.

Documentation

The datasheets and user guides for the CC3220S, Codec and boards can be found at:

• Codec documentation:
  • TLV320AIC3254 Ultra Low Power Stereo Audio Codec with Embedded miniDSP datasheet
  • TLV320AIC3254 Application Reference Guide
  • Design and Configuration Guide for the TLV320AIC3204 and TLV320AIC3254 Audio Codecs
• CC3220S documentation:
  • CC3220 SimpleLink™ Wi-Fi® Wireless and Internet-of-Things Solution, a Single-Chip Wireless MCU datasheet
  • CC3220 SimpleLink™ Wi-Fi® and Internet of Things Technical Reference Manual
  • SimpleLink MCU SDK User's Guide
  • CC3200 Peripheral Driver Library User's Guide Documentation
  • SimpleLink MCU SDK Driver API Reference
  • CC3220 SimpleLink™ Wi-Fi® and Internet of Things Solution, a Single-Chip Wireless MCU. Getting Started Guide
  • CC3x20, CC3x35 Simple Link™ Wi-Fi® and Internet of Things Network Processor Programmer's Guide
• CC3200AUDBOOST board:
  • CC3200AUDBOOST User's Guide
  • CC3200AUDBOOST schematics
• CC3220 LAUNCHXL board:
  • CC3220 SimpleLink™ Wi-Fi® LaunchPad™ Development Kit Hardware User's Guide
  • SimpleLink™ Wi-Fi® CC3220 Out-of-Box Application Quick Start Guide
  • SimpleLink™ Wi-Fi® CC3220 Out-of-Box Application User's Guide
  • UniFlash CC3x20, CC3x35 SimpleLink™ Wi-Fi® and Internet-on-a chip™ Solution ImageCreator and Programming Tool User's Guide

The CC3220S SOC and C3254 Codec are both complicated IC's and the documentation can be quite overwhelming at first.

Lab Work Handbook

The Lab Work Handbook used in the TDS02 course can be found here:

• Lab_Work_Handbook_TDS02.pdf. This version is meant to be printed on paper (double sided).
• Lab_Work_Handbook_TDS02_ebook.pdf. This version is meant to be read on a screen.
• The LaTeX sources can be found here: https://bitbucket.org/HR_ELEKTRO/tds02/. When you find an error, please report it to https://bitbucket.org/HR_ELEKTRO/tds02/issues?status=new&status=open.

Notes on developing an IIR filter using MATLAB's filter design tool

Developing an IIR filter using MATLAB's filter design tool proved to be more difficult than expected. See these notes: Notes on developing an IIR filter using MATLAB's filter design tool.