QF1Da512 Audio SavFIRe

Transcription

1 With the unique features of the QF1Da512 integrated circuit, Quickfilter Pro Software for QF1Da512, and, it is possible to create a stereo equalizer with spatialization in a single chip. The procedure outlined below will help the user design, implement and test this configuration. Setup In order to implement a single chip stereo equalizer with spatialization, the user must have the following: 1. QF1D512-DK - SavFIRe development kit 2. QF1Da512-DK Audio SavFIRe development kit (this is a daughter card that mounts to the QF1D512- DK) and 3. The latest version (1.3 or higher) of the Quickfilter Pro Software for QF1Da512. For more information on the operation of the QF1D512 Development Kit and software please refer to the QF1D512-DK User Guide. For more information on the operation of the QF1Da512 Development kit and software, please refer to the QF1Da512 User Guide. Both of these documents as well as the link to download the software can be found at 4. Mount the QF1Da512 daughter card as shown in figure 1. Figure 1 5. Connect power to the daughter card with the supplied power supply and connect the QF1D512-DK to the PC with the supplied USB cable (see respective User s Guides). 6. Launch Quickfilter Pro Software for QF1Da512. Rev A1, July

2 STEP 1 Create the original transfer It is assumed the user has created the original speaker transfer function. If not, then the user can create the initial transfer function using their preferred method. Quickfilter s spatialization solution will utilize source data for both channels and requires a common transfer function for both speakers. The resulting transfer function data needs to be in a 2-column text file with the first column being frequency and the second column being amplitude separated with a comma. Figure1A Original transfer function as a.txt file STEP 2 Import the original transfer function into QuickfilterPro Upon launching Quickfilter Pro Software for QF1Da512, the screen in Figure 2A should appear. If it does not, the user should make sure he is in Advanced User Mode by selecting Options then Advanced User Mode as shown in Figure 2B. Rev A1, July

3 Figure 2A Startup Screen Rev A1, July

4 Figure 2B Advanced User Mode As shown in Figure 2A, the chip defaults are I2S. If a different mode is required, then click Chip, then select Data Format Editor to change the QF1Da512 default data format (Figures 2C and 2D). For more information on the functions of the Data Format Editor, refer to the Quickfilter Pro Software for QF1Da512 User Guide. Rev A1, July

5 Figure 2C Select Data Format Editor Rev A1, July

6 Figure 2D Data Format Editor Next, press the New Filter button to design a new filter for Chip B. A new window opens up with a series of buttons for designing different types of filters. Select the Draw Freeform filter button. Rev A1, July

7 Figure 2E Design a new filter Rev A1, July

8 Figure 2F Choose Draw Freeform Filter Rev A1, July

9 Select the open file icon which will prompt you to locate the file you wish to import (this is the common speaker transfer function created in Step 1 for both speakers). Figure 2G Select open file Browse to the file and select it then press open (Figure 2H). The transfer function will be loaded into the filter editor window where you can then begin to design the filter (Figure 2I). Rev A1, July

10 Figure 2H Select file and load it Rev A1, July

11 Figure 2I Original transfer function loaded Quickfilter software sets the default sampling frequency at 48,000 Hz and the number of taps to the maximum value (511). The user may change these if so desired by highlighting the respective box and changing the value. Note that Dual Channel mode is required for Spatialization and will limit the maximum taps to 255 as is done for all Dual Channel mode options. STEP 3 Create the inverse transfer function in QuickfilterPro To create the inverse transfer function (equalization filter), click on the Invert Data Button (Figure 3A) and the original transfer function will be inverted and the coefficients scaled (Figure 3B). Rev A1, July

12 Figure 3A Invert Data Button Rev A1, July

13 Figure 3B Original transfer function inverted and scaled To use this curve to equalize both left and right channels in a single chip, select options then Dual Channel Mode (Figure 3C). A dialog box will appear (Figure 3D) which gives the user several options Rev A1, July

14 Figure 3C Selecting Dual Channel Mode Rev A1, July

15 Figure 3D Dual Channel Mode Options The default option is for single channel mode (one filter for either left or right channels). Selecting either of the next two options allows a single filter to operate on both left and right channels in a single chip. The final option adds spatialization. If the final option is selected, it defaults to allow a single filter to operate on both left and right channels as well as adding the spatialization effect. For spatialization, a number between 0 and 0.6 can be entered in the box depending upon the user preference. A value is settled upon by an iterating the spatialization constant and listening to the result until the user is satisfied with the listening experience. Pressing the OK button in this dialog returns the user to the filter editor window, with the selected options enabled (Figure 3E). Rev A1, July

16 Figure 3E Filter with Dual Mode and spatialization enabled Note that the number of taps has decreased from the default of 511 to a new default of 255. At this point, the user is able to add gain to the filter. Generally, FIR filters, when used in equalization, will have the effect of reducing gain through the filter block. If the target system can not compensate for the gain then, enabling the gain function will set the filter block to unity gain (from input to output of the QF1Da512 chip). To add gain, click on the checkbox Apply Gain and Compression (Figure 3F). The user can then accept Quickfilter s default gain and compression settings, or by clicking the Override QF Calculated Values checkbox, input his own values for gain and compression (for a full discussion of how the gain and compression block operates, please refer to the Quickfilter Pro Software for QF1Da512 Help Guide and the QF1Da512-DK Users Guide). Rev A1, July

17 Figure 3F Adding Gain Press the design filter button and the final filter will be displayed (Figure 3G). At this point, it is recommended that user save the inverted transfer function data in case additional editing is required. To save the inverted transfer function data, click the Disk icon and save the filter to the location of choice. (For a complete discussion of editing the designed filter, please refer to The Quickfilter Pro Software for QF1Da512 Help Guide, and Application Brief QFAB004 Creating Inverse Transfer Functions with the QuickfilterPro Software. Pressing done will load the filter into Chip B of the configuration screen (Figure 3H). Rev A1, July

18 Figure 3G Design Filter Rev A1, July

19 Figure 3H Final filter loaded into Chip B Notice that the Data Select Edge box indicates that the chip will filter data on both the rising and falling edges of DSEL. This is what enables a single chip to filter both channels of a stereo audio stream. At this point, it is recommended that user save the configuration in case later editing is required. To save the configuration for Chip B, go to File, then Save, and save the filter to the location of choice. (For a complete discussion of editing the designed filter, please refer to The Quickfilter Pro Software for QF1Da512 Help Guide, and Application Brief QFAB004 Creating Inverse Transfer Functions with the QuickfilterPro Software When filtering both channels and adding spatialization in a single chip (in this case Chip B), it is necessary to bypass Chip A. This is done by clicking the Bypassed check box under Chip A (Figure 3I). Rev A1, July

20 Figure 3I Bypassing Chip A It is also recommended that a flat (0dB) filter be placed into Chip A. To do this, click the new button, then click the Draw Freeform Filter button (as in the beginning of this Step 3) to enter the filter Editor. The Create Line button is automatically highlighted (Figure 3J). The dashed line in the screen is the 0dB line. Using the line tool, place a couple of points on the 0dB line, then hit Design Filter and a 0dB flat filter will have been created (Figure 3K). Clicking Done returns the user to the configuration screen where the flat filter is loaded into Chip A (Figure 3L). Rev A1, July

21 Figure 3J Create Line function Rev A1, July

22 Figure 3K 0dB flat filter Rev A1, July

23 Figure 3L Flat filter loaded into chip A Pressing Start will load the filters into the QF1Da512 development kit and the user can view the FFT for each chip in the window (Figure 3M). With an audio source and the measured speakers connected to the QF1Da512 development kit, the user can listen to equalized and spatialized audio. To do comparison testing, the user needs only to check the Pass-through Chip B box to bypass the filter and listen to un-equalized and unspatialized audio. This mode also allows the user to perform real time edits to both the equalization filter and the spatialization constant. To do this, the user clicks Stop, then Edit under Chip B and edits can be made and loaded. When loaded, pressing start loads the edited filter into Chip B. Rev A1, July

24 Figure 3M Filters loaded and running When satisfied with the filters, select each channel and save the configuration (see Figure 3N and figure 3O). This operation is different than the save done in the Filter Editor. The Save in the Filter Editor is designed to save the points on the graph so that they can be re-imported for editing at a later time. The Save in the configuration window saves the coefficients, and the data mode and pin settings for each chip. This is the file that will eventually be used to create the production EEprom file. Rev A1, July

25 Figure 3N Saving the configuration for Chip A Rev A1, July

26 Figure 3O Saving the configuration for Chip B STEP 4 Stand-alone Mode With the QF1Da512-DK development kit, the user has 2 modes of operation. The first (what has been discussed so far) is the daughter card mode (the QF1Da512-DK is mounted on the QF1D512-DK). There is a second mode (Stand-alone mode) available, however. This stand-alone mode allows the user to connect to his audio devices without having to tether to a PC. To do this, the QF1Da512-DK must have the filter configurations programmed into it. Rev A1, July

27 STEP 5 Programming the QF1Da512-DK for Stand-alone mode Once the filters in Steps 1-4 have been designed, and the QF1Da512-DK still mounted to the QF1D512-DK, make sure that the filters are stopped (by pressing the Stop button) on the main screen (see Figure 5A) Figure 5A Stop Run Mode Go to the file menu, then to Export to External Host, and highlight AVR Flash On Board (Figure 5B) Rev A1, July

28 Figure 5B Export to External Host A new window pops up (see Figure 5C) and the user may load Configuration A and Configuration B into either Red or White Channels (these correspond to the RCA connectors on the QF1Da512-DK board. Rev A1, July

29 Figure 5C Loading the configurations Pressing download will then program the flash on the QF1Da512-DK development kit (see Figure 5D) Rev A1, July

30 Figure 5D Downloading configurations to Flash When done, click the Close Button, remove power from the QF1Da512-DK, disconnect the USB cable from the QF1D512-DK, and remove the QF1Da512-DK from the QF1D512-DK. The QF1Da512-DK is now capable of filtering and equalizing without the need for the motherboard. Apply power, connect an audio source and speakers, and perform listening tests. The QF1Da512-DK also has a bypass button, so that comparison tests can be done between equalized and un-equalized configurations. Rev A1, July

31 References: Datasheet QF1D512-DK User s Guide QF1Da512-DK User s Guide Quickfilter Pro for QF1Da512 Help Guide QFAB004 Creating Inverse Transfer Functions with the QuickfilterPro Software Contact Information: Quickfilter Technologies, Inc S. Greenville Avenue, Suite 100 Allen, TX General:info@quickfilter.net Applications:apps@quickfilter.net Sales:sales@quickfilter.net Phone: Fax: The contents of this document are provided in connection with Quickfilter Technologies, Inc. products. Quickfilter makes no representations or warranties with respect to the accuracy or completeness of the contents of this publication and reserves the right to make changes to specifications and product descriptions at any time without notice. No license, whether express, implied, arising by estoppels or otherwise, to any intellectual property rights is granted by this publication. Except as set forth in Quickfilter's Standard Terms and Conditions of Sale, Quickfilter assumes no liability whatsoever, and disclaims any express or implied warranty, relating to its products including, but not limited to, the implied warranty of merchantability, fitness for a particular purpose, or infringement of any intellectual property right. Rev A1, July

32 Quickfilter's products are not designed, intended, authorized or warranted for use as components in systems intended for surgical implant into the body, or in other applications intended to support or sustain life, or in any other application in which the failure of Quickfilter's product could create a situation where personal injury, death, or severe property or environmental damage may occur. Quickfilter reserves the right to discontinue or make changes to its products at any time without notice Quickfilter Technologies, Inc. All rights reserved. Quickfilter, the Quickfilter logo and combinations thereof, are trademarks of Quickfilter Technologies, Inc. Other product names used in this publication are for identification purposes only and may be trademarks of their respective companies Rev A1, July