LM4934 I2C/SPI Interface Software Manual v1.0

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1 LM4934 I2C/SPI Interface Software Manual v1.0 National Semiconductor Application Note 1492 Daniel Andersen May 2006 Table of Contents Introduction... 2 Installation... 2 Overview... 2 Default All Button... 4 BASIC Tab... 4 PLL Tab... 7 FIR Filter Tab... 9 Advanced Tab... 9 References Revision History LM4934 I2C/SPI Interface Software Manual v1.0 AN National Semiconductor Corporation AN

2 AN-1492 Introduction The LM4934 Software provides easy read/write access to the data registers of the LM4934 audio subsystem through an I2C/SPI control interface. This manual will provide instruction on how to use this software with the LM4934 demo board and associating USB interface card. Furthermore, examples will be provided on using the software to program the headphone and loudspeaker outputs, setting the PLL, and other features of the LM4934 audio subsystem. Installation The LM4934 software will run on all Microsoft Windows OS computers with USB support and is built on a new Microsoft.NET Framework. It may require that Microsoft.NET Framework Software Development Kit (SDK) version 1.1 be installed in your computer, which is downloadable through the Microsoft website 1. The LM4934 software setup does NOT include Microsoft.NET Framework Software Development Kit (SDK) version 1.1 if your PC requires it. An internet connection is required to download this patch if necessary since Microsoft.NET Framework Software Development Kit (SDK) version 1.1 is not included in the LM4934 software package and may or may not be present on your computer with other updates from Microsoft. Microsoft.NET Framework may be found at the following link: details.aspx?familyid=9b3a2ca f41- A333C6B9181D&displaylang=en Installation of the SDK may take a few minutes. Once that is completed the rest of the installation process is fast. The following steps should be followed: Step 1: Uninstall any previous version, if any, from Control Panel/Add Remove Program/LM4934 I2C SPI interface. Step 2: Unzip the LM4934 software. Step 3: Run the Setup.exe file. Step 4: The LM4934.exe file will be installed to your desktop as well as the folder you specified during the installation process. Step 5: Please make sure that the LM4934 demo board and USB Interface Card are properly connected to your PC and that proper power is applied to the LM4934 demo board. Step 6: Run the LM4934.exe file. The LM4934 software will run properly ONLY if Step 5 is completed, since a functioning USB connection is required. Overview The LM4934 Software is divided up into three main sections: Menu Bar, Control Tabs, and Status Register and Bar. (please refer to Figure 1) The Menu Bar contains File, Control, Settings and Help Options: File: Exits program Control: Switches between I2C and SPI mode. Switching between I2C and SPI will initialize all of the data registers back to their default settings of zero. Selecting I2C also allows the selection of the I2C address setting Address 0 or 1. These settings are automatically configured on the board when selected. Settings: Sets the USB interface board s regulated output voltage to 3V or 3.8V. Help: Contains the About box, which can be used to check Version number of the software. Control Tabs are further divided up to following: BASIC: Contains the main functionality of the LM4934 chip. PLL: Contains PLL control settings, DAC settings, and interface settings. FIR: Controls 5-tap digital FIR filter on DAC. Advanced: Provides read/write access to any register using brute force (register level controls). The Status Register and Bar provide feedback on the communication status between the USB interface card/lm4934 demo board to the LM4934 software. The Status Bar has useful messages that provide feedback on the communication status of the I2C/SPI control interface. Status Messages (please refer to Figure 1): 1) If there is a proper connection between the PC and the LM4934 demo board/usb interface card, the message USB Connected will appear. If there is not a proper connection than USB I/O error will appear. 2) For I2C mode, an I2C Mode message indicates operation in I2C control. For SPI mode the message SPI Mode appears. 3) Shows two hex numbers. The first number shows the data register address (0xch) and the second number shows the data byte (0x11h). (Figure 1) 2

Overview (Continued) AN-1492 20196601 FIGURE 1.

3 Overview (Continued) AN FIGURE 1. A Main View of LM4934 Software (BASIC Tab) 3

AN-1492 Default All Button Pressing this button (located in upper right, Figure 1) will reset the software back to its default state and will initialize all of the data registers back to their

4 AN-1492 Default All Button Pressing this button (located in upper right, Figure 1) will reset the software back to its default state and will initialize all of the data registers back to their default setting of zero. BASIC Tab i) Mode Control Register (Mode Control 0x00h) The LM4934 can be placed in one of eight modes. The mode dictates whether the part is in shutdown and also controls input source mixing for all outputs. Modes 0 through 7 are described in the table below. Additionally, each output will show either its shutdown status or mix ratio in the window above the Mode Control buttons as shown in Figure FIGURE 2. Mode Control Mode Mono Lineout Mono Earpiece Loudspeaker L Loudspeaker R Headphone L Headphone R 0 SD SD SD SD SD SD 1 M M M M M M 2 AL+AR AL+AR AL AR AL AR 3 M+AL+AR M+AL+AR M+AL M+AR M+AL M+AR 4 DL+DR DL+DR DL DR DL DR 5 DL+DR+AL+AR DL+DR+AL+AR DL+AL DR+AR DL+AL DR+AR 6 M+DL+AL+DR+AR M+DL+AL+DR+AR M+DL+AL M+DR+AR M+DL+AL M+DR+AR 7 M+DL+DR M+DL+DR M+DL M+DR M+DL M+DR SD = Shutdown M = Mono Input AL = Analog Left Channel AR = Analog Right Channel DL = I2S DAC Left Channel DR = I2S DAC Right Channel FIGURE 3. Mode Control Mixer Window (Mode 0, all shutdown, shown) 4

Output Control simply toggles whether the output is on or off. AN-1492 20196604 FIGURE 4. LM4934 Output Control iii) Volume Control and Gain Operations 20196605 FIGURE 5.

5 BASIC Tab (Continued) ii) Output Control Register (Output Control 0x01h) Each output may be toggled active by selecting the check box next to it. Any combination of outputs may be selected including all or none. Source mixing is done by the Mode Control and is viewable in the Mode Control Mixer Window (see Figure 3). Output Control simply toggles whether the output is on or off. AN FIGURE 4. LM4934 Output Control iii) Volume Control and Gain Operations FIGURE 5. Output Volume Controls 1) MONO VOLUME (0x02h). Controls the volume of the Mono earpiece output. 2) HEADPHONE VOLUME LEFT (0x05h). Controls the volume of the left channel headphone output. This volume may be locked to match the right headphone volume by checking the key button next to it. This enables simultaneous volume control of both channels equally. 3) HEADPHONE VOLUME RIGHT (0x06h). Controls the volume of the right channel headphone output. This volume may be locked to match the left headphone volume by checking the key button next to it. This enables simultaneous volume control of both channels equally. 4) LOUDSPEAKER VOLUME LEFT (0x03h). Controls the volume of the left channel loudspeaker output. This volume may be locked to match the right loudspeaker volume by checking the key button next to it. This enables simultaneous volume control of both channels equally. 5) LOUDSPEAKER VOLUME RIGHT (0x04h). Controls the volume of the right channel loudspeaker output. This volume may be locked to match the left loudspeaker volume by checking the key button next to it. This enables simultaneous volume control of both channels equally. 5

AN-1492 BASIC Tab (Continued) 20196606 FIGURE 6. Preamp Controls 6) Left DAC Gain Select (0x08h). Controls the left channel DAC preamp gain before the mode control mixer.

Controls the mono analog input level before it reaches the mode control mixer. 9) LEFT Analog Input Amplifier Gain Select (0x07h).

Controls the right channel analog input level before it reaches the mode control mixer.

6 AN-1492 BASIC Tab (Continued) FIGURE 6. Preamp Controls 6) Left DAC Gain Select (0x08h). Controls the left channel DAC preamp gain before the mode control mixer. 7) Right DAC Gain Select (0x08h). Controls the right channel DAC preamp gain before the mode control mixer. 8) Mono Analog Input Amplifier Gain Select (0x08h). Controls the mono analog input level before it reaches the mode control mixer. 9) LEFT Analog Input Amplifier Gain Select (0x07h). Controls the left channel analog input level before it reaches the mode control mixer. 10) RIGHT Analog Input Amplifier Gain Select (0x07h). Controls the right channel analog input level before it reaches the mode control mixer. iv) 3D Enhancement Controls 3D is an effect used with headphones or near-field stereo speaker setups (where the speakers are very close to each other). The 3D audio effect on the LM4934 is a form of crossfeed network that may be modified by both software control (level settings below) and hardware modification by changing the external capacitance value on the R3DOUT and L3DOUT pins. 1) 3D enables or disables the effect. 2) 3D Mode Control selects whether 3D type 1 or 2 is used. 3) 3D Enhancement Level Select determines the amount of crossfeed between the two channels. The selected percentage translates to roughly that amount of the left channel being fed into the right, and vice versa. v) Headphone Mode Control Headphone mode may be selected in software as either OCL (output-capacitor-less) or SE (single-ended). Hardware must be correctly in place before selection. OCL mode requires direct connections to the headphone load (no DC blocking caps, headphone sleeve is 1 2 V DD ). SE mode requires DC blocking caps on each channel and a ground connection to the headphone sleeve. Operating the LM4934 in OCL mode with the sleeve tied to GND may result in higher current use and possible shutdown of the part FIGURE 8. Headphone Mode Control FIGURE 7. 3D Enhancement Controls 6

PLL Tab This tab programs the settings of the Phase Lock Loop (PLL) and has controls for the DAC and I2C setup. AN-1492 20196609 FIGURE 9.

7 PLL Tab This tab programs the settings of the Phase Lock Loop (PLL) and has controls for the DAC and I2C setup. AN FIGURE 9. PLL Tab i) MCLK Drop Down Menu Mode 1) In the drop down combo box of MCLK (which is based on common system clock values) the user can select from a list of pre-programmed MCLK inputs (see Figure 10). Based on the value of MCLK that is chosen from the drop down menu, the LM4934 software will automatically update the M, N, N_MOD and P values according to the MCLK input value and the frequency of the PLL OUTPUT will be calculated in real time. The LM4934 runs optimally with a PLL OUTPUT of 12 MHz or MHz. 2) In the PLL_OUTPUT drop down combo box, a 12 MHz (Fs = 48 khz) or MHz (Fs = 44.1 khz) target value can be selected and again the M, N, N_MOD and P values will be calculated based on the value chosen in the PLL OUTPUT and MCLK drop down combo boxes. (see Figure 9) 3) The Program PLL Registers button should be clicked after the correct PLL register fields have been set. 4) The audio DAC input sources must be set for PLL OUTPUT if the PLL is to be used. 5) The PLL must then be enabled. 6) The PLL settings also include a FAST CLOCK option that divides the input clock to the PLL by 2 and an R DIVIDER option that divides the PLL output clock in any ratio from 1 to

AN-1492 PLL Tab (Continued) 1) DAC MODE Oversampling controls the oversampling ratio of the DAC, from 128x to 32x. Most common usage will be 125 and 128 times.

3) DAC dither may be controlled here, as well as whether dither is always present or not. 20196612 20196610 FIGURE 10.

The M, N, N_MOD and P values are not automatically updated as they were when using the MCLK Drop Down Menu Mode.

8 AN-1492 PLL Tab (Continued) 1) DAC MODE Oversampling controls the oversampling ratio of the DAC, from 128x to 32x. Most common usage will be 125 and 128 times. 2) DAC channels may be muted independently. Enabling mute on either DAC channel will result in no output from the DAC on that channel. 3) DAC dither may be controlled here, as well as whether dither is always present or not FIGURE 10. MCLK Dropdown ii) User Defined MCLK or I2S CLK Mode The user can also choose their own MCLK or I2S CLK value by simply entering that value into the corresponding input field. The M, N, N_MOD and P values are not automatically updated as they were when using the MCLK Drop Down Menu Mode. The M, N, N_MOD and P should be adjusted manually by the user to achieve a PLL OUTPUT calculated value of 12 MHz (Fs = 48 khz) or MHz (Fs = 44.1 khz). The only time that the M, N, N_MOD and P values are automatically calculated is when MCLK is chosen from the pre-programmed list of values on the drop down menu for MCLK. INTERFACE AND DAC SETUP FIGURE 12. Interface Control The Interface Control (see Figure 12. Also bottom right, Figure 8) controls the interface configuration for both the digital audio bus (I2S) and the main control bus (I2C only). 1) The I2S bus may be set as either a master or slave. In master mode, the master I2S clock (BITCLOCK) and frame clocks (FCLK) are generated by the LM4934 based on the PLL and MCLK configurations. In slave mode the LM4934 will respond to external I2S clocks. 2) I2S MODE selects the format for the I2S data: either typical I2S data (2 bit shift to the right after frame clock edge) or left justified data (data starts on frame clock edge). 3) I2S resolution may be selected as either 16 or 32 bits. This is relevant for master mode only. 4) The I2C clock may be set as FAST to allow I2C operation of up to 3.4 MHz. Disabling allows typical I2C operation of up to 400 khz FIGURE 11. DAC Setup Interface The 18-bit stereo audio DAC may be configured with the DAC setup controls (see Figure 11. Also top right, Figure 8). Care should be taken that changes to the DAC setup are done when in either an analog-only mode or when the part is in mode 0 (shutdown). Failure to do this may result in DAC malfunction. 8

FIR Filter Tab AN-1492 20196613 FIGURE 13. FIR Filter Control Tab This tab controls the FIR filter parameters on the digital section of the LM4934.

9 FIR Filter Tab AN FIGURE 13. FIR Filter Control Tab This tab controls the FIR filter parameters on the digital section of the LM4934. The LM4934 features a 5-tap FIR filter that may be used for frequency response modification on the digital audio portion of the part. The FIR filter is typically used as a digital decimation filter on the output of the DAC, but it may be used for other high-pass/low-pass/ band-pass filter configurations as well. Since an FIR filter is symmetric, only three filter coefficients need be specified. C0 is the same as C4. C1 is the same as C3. Coefficients in two s complement form and are specified from to Coefficients may easily be obtained by many filter design or math programs, but will typically be between 1 and 1. In this case, normalizing the coefficients to the to baseline is necessary. To do this, simply divide each coefficient value by the largest value of the group and then multiply all by For example, with a LPF design specifying a 48 khz sample frequency, filter cutoff 1 at 10 khz, filter cutoff 2 at 11 khz, 60 db of attenuation and a ripple factor of 0.1 gives me the following coefficients (obtained through a standard FIR filter design program): , , , , Notice they are symmetric. Next, divide all coefficients by (the largest value of the group). This gives: , , 1, , Multiplying all values by (half the range): , , 32767, , This gives us our final coefficient values. It is important to note that these values may then be linearly scaled up or down by multiplying all values by a constant. Exceeding DAC levels may result in clipping or improper DAC operation, so care should be taken the filter coefficients do not boost certain frequencies above clipping values. Use of the DAC preamp can also help mitigate this. The FIR filter slider bars may also be manipulated manually while the device is operating to observe the apparent effect on audio outputs. FIR filter compensation must be enabled and the LM4934 operating in a digital audio mode for this to work. Advanced Tab This tab allows the user to directly program a specific data register of their choosing. This tab is useful for system debug and verification of register-level commands. 9

AN-1492 Advanced Tab (Continued) 20196614 1) This drop down menu allows the user to select a specific data register to write to.

10 AN-1492 Advanced Tab (Continued) ) This drop down menu allows the user to select a specific data register to write to. 2) This row of 8 buttons sets the bit7 to bit0 data of the specified register. Each button press will trigger an I2C/SPI write. 3) This will write the current data field to the specified register. References 1) Microsoft framework.net 1.1 Direct download link details.aspx?familyid=9b3a2ca f41- A333C6B9181D&displaylang=en 10

11 Revision History Rev Date Description /25/06 Initial WEB release. National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications. For the most current product information visit us at LIFE SUPPORT POLICY NATIONAL S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. 2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. BANNED SUBSTANCE COMPLIANCE National Semiconductor follows the provisions of the Product Stewardship Guide for Customers (CSP-9-111C2) and Banned Substances and Materials of Interest Specification (CSP-9-111S2) for regulatory environmental compliance. Details may be found at: Lead free products are RoHS compliant. National Semiconductor Americas Customer Support Center new.feedback@nsc.com Tel: National Semiconductor Europe Customer Support Center Fax: +49 (0) europe.support@nsc.com Deutsch Tel: +49 (0) English Tel: +44 (0) Français Tel: +33 (0) National Semiconductor Asia Pacific Customer Support Center ap.support@nsc.com National Semiconductor Japan Customer Support Center Fax: jpn.feedback@nsc.com Tel: LM4934 I2C/SPI Interface Software Manual v1.0 AN-1492

The LM4935 Headset/Push-Button Detection Guide

The LM4935 Headset/Push-Button Detection Guide Overview The LM4935 features an advanced headset detection scheme that can sense the insertion or removal of any type of available headset. The headset detect