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Kit Operation
To the right, the next group box contains controls for resetting the TLV320AIC33. A software reset can be
done by writing to a register in the TLV320AIC33, and this is accomplished by pushing the button labeled
Software Reset. The TLV320AIC33 also may be reset by toggling a pin on the TLV320AIC33, which is
done by pushing the Hardware Reset button.
CAUTION
In order to perform a hardware reset, the RESET jumper (JMP19) must be
installed and SW2-7 on the USB-MODEVM must be turned OFF. Failure to
do either of these steps results in not generating a hardware reset or
causing unstable operation of the EVM, which may require cycling power
to the USB-MODEVM.
The ADC Overflow and DAC Overflow indicators light when the overflow flags are set in the
TLV320AIC33. These indicators, as well as the other indicators on this panel, are updated only when the
software's front panel is inactive, once every 20ms. Below these indicators are other indicators that show
when the AGC noise threshold is exceeded. To the far right on this screen, the short-circuit indicators
show when a short-circuit condition is detected, if this feature has been enabled. Below the short-circuit
indicators is a bar graph that shows the amount of gain which has been applied by the AGC, and
indicators that light when the AGC is saturated.
6.6.1
Audio Analyzer
Near the left side of the screen is a button labeled Audio Analyzer, and this button can be set to ON or
OFF. Pressing the button to turn it ON opens another window (see
). This feature provides the
ability to generate signals to send to the TLV320AIC33 DACs as well as viewing and analyzing signals
read by the TLV320AIC33 ADCs. This ability to view and process the real-time streaming USB audio is a
demanding task. Use of the Audio Analyzer feature requires a computer with at least 512MB of memory
and reasonable processor speed (> 1GHz); computers with inadequate resources could still use the Audio
Analyzer to generate signals for the DACs, but will be unable to process signals from the ADCs because
the FFT, distortion analysis, and signal-to-noise ratio analysis will not be able to keep up with the data
processing requirements.
The Audio Analyzer features two tabs. The front tab, shown in
and titled Generator, creates
digital waveforms to send to the DACs. When first started, the function will be set to SNR (Output Zeros)
which feeds only zero codes to the DAC. This is commonly done to test for the noise floor of the DAC.
The second function available is THD (-1dB sinewave). This function sends a sinewave at a coherent
frequency to the 44.1kHz sample rate to the DACs; this is commonly used for testing THD+N.
These first two functions do not require any further settings; therefore, the frequency and amplitude knobs
below the function selector are not used. Selecting a function of Function Generator allows the choice of
waveform shape by using the pull-down menu next to the function selector, and the frequency and
amplitude of that signal can be varied using the knobs below.
The output waveforms for both left and right channels are displayed in the graph at the bottom of this
screen.
TLV320AIC33EVM and TLV320AIC33EVM-PDK User's Guide
12
SBAU114 – November 2005