AN1250 STMicroelectronics, AN1250 Datasheet - Page 13

• Manufacturer Part Number: AN1250
• Description: STA014/STA015 MPEG LAYER III DECODER AND ADPCM CODEC
• Manufacturer: STMicroelectronics

Should the test fail check the PC parallel port settings: most PC, infact, can configure their LPT interface in dif-
ferent modes (SPP/EPP/ECP) and it could happen that some of these configurations are not well suited to con-
trol our evaluation kit
Moreover, in order to be able to operate the PC parallel port at maximum speed, it's important to properly setup
the 'I/O recovery time' in the machine BIOS; this setting is tipycally available in the 'Chipset Features' page. The
minimum available value must be set for both 8 and 16 bits I/O recovery time; choose NA (not available) option
if present.
Improperly settings of these options could prevent the LPT interface to work up to the minimum required speed
in order to correctly decode 320kbit/s MP3 streams and to encode/decode highest bitrate ADPCM messages.
8 CONTROL SOFTWARE
In order to control and evaluate the STA014/STA015 board a dedicated control panel has been developed: it
runs on Win95/98 operating system and allows both MP3 and ADPCM capabilities to be evaluated.
Hereby is a quick description of the various controls available on it.
8.1 Main page
Figure 12. Main page
§ 1 : The 'Controls' section groups the MP3 audio controls such as volumes, tones and global attenuation.
The left/right volume sliders can be linked together checking the 'Left/Right Lock' box. The dual band
equalizer can be adjusted both in frequency and enhancement. Special care must be taken before
enhancing bass/treble: infact, in order to avoid any distortion, the 'Tone Attenuation' slider must be
previously set to the maximum value of bass/treble desired enhancement.
AN1250 APPLICATION NOTE
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