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Application Report
SLAA482–January 2011
Setting TAS5717EVM/TAS5719EVM Environment Variables
Matt Lauer ................................................................................................................. Audio Products
ABSTRACT
This application report describes how to set the Microsoft
®
Windows
®
environment variables for correct
I
2
C™ operation of the TAS5717EVM and TAS5719EVM evaluation modules (EVMs). The proper
environment variables must be set in order for the TAS5717 and TAS5719 amplifiers to communicate
properly over the I
2
C interface.
Throughout this document, the abbreviation TAS57xx applies to the entire family of related devices, unless
otherwise indicated.
Contents
1 Introduction .................................................................................................................. 1
2 Equipment Configuration ................................................................................................... 1
3 Testing I
2
C Communication ................................................................................................ 3
4 Changing Environment Variables for Other Devices ................................................................... 4
5 Conclusion ................................................................................................................... 4
List of Figures
1 Selecting Properties from the Windows Start Menu.................................................................... 2
2 System Properties and Environment Variables Dialog Boxes ........................................................ 2
3 Edit User Variables Dialog................................................................................................. 3
4 I
2
C Communication Dialog................................................................................................. 3
1 Introduction
Most devices in the TAS57xx audio amplifier series have a 7-bit I
2
C address of 0x36 (0011 011). These
devices can also have an address of 0x34 (0011 010) if the A_SEL pin (or similar pin) is pulled low. Both
the TAS5717 and TAS5719 devices have an address of 0x54 (0101 010) or 0x56 (0101 011), depending
on the polarity of A_SEL (external pulldown for 0x54; external pullup for 0x56, respectively). The current
graphical user interface (GUI) software for the TAS57xx devices create a Windows environment variable
that references only the 0x36 address. Without the correct I
2
C address, the PC cannot properly
communicate with either the TAS5717EVM or TAS5719EVM, so the user must change this environment
variable to ensure valid communication. The next section explains how to set the Windows environment
variable correctly.
2 Equipment Configuration
2.1 Equipment/Setup
The user must have either the TAS5717EVM or TAS5719EVM, one of the MC57xxPSIA interface boards,
and a USB to mini-USB cable. Connect the respective EVM to the MC57xxPSIA board.
Microsoft, Windows are registered trademarks of Microsoft Corporation.
I
2
C is a trademark of NXP Semiconductors.
All other trademarks are the property of their respective owners.
1
SLAA482–January 2011 Setting TAS5717EVM/TAS5719EVM Environment Variables
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