WM8816-MICRO-EV1M データシートの表示（PDF） - Wolfson Microelectronics plc

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WM8816-MICRO-EV1M

WM8816 Micro-Controller Board User Handbook

Wolfson Microelectronics plc 

KEYPAD LAYOUT

.

WM8816-MICRO-EV1M

↑

VOL.

←

BAL.

CENTRE

BAL.

↓

VOL.

MUTE

DISP.

FRONT

→

BAL.

REAR

CENTRE

/LFE

P.REF P.STAT

Figure 2 Keypad Layout

The following sections describe the function of each of these keys.

SETTING THE VOLUME

The volume is set using the up and down arrow keys marked “Vol.”. The up arrow increments the

volume in 0.5dB steps whilst the down arrow decrements the volume in 0.5dB steps. The applied

gain can be varied between +15.5dB and –111.5dB. Holding down the keys causes the output

volume level to be changed faster.

When either of the “Vol.” keys are pressed, LED (D7) is illuminated, and the output display (U2 & U8)

is updated to show the latest volume, in dB.

ADJUSTING THE BALANCE SETTING

The left and right arrow keys, marked “Bal.”, are used to adjust the relative loudness of each channel.

Attenuating the opposite channel makes one channel (apparently) louder.

The left arrow shifts the balance towards the left channel in 0.5 dB steps. Similarly the right arrow

key shifts the balance towards the right channel in 0.5dB steps. Pressing the “Centre Bal.” key

equalises the volume emitting from both channels.

When any of the balance keys is pressed LED (D6) is illuminated and the output display (U2 & U8) is

updated to indicate the latest setting. Balance settings are displayed as a 3 digit number preceded

by an ‘L’ or ‘R’. The letter ‘L’ indicates that the left channel is the loudest channel, whilst the letter ‘R’

indicates that the right channel is the loudest channel. The following number indicates how many

dB’s the opposite channel has been attenuated to achieve the balance effect. For example a display

of R45.5 indicates that the balance is currently set towards the right channel – and that to achieve

this the left channel has been attenuated by 45.5dB.

Holding down either of the left / right balance keys causes the settings to change much faster. The

maximum volume difference that can be set between channels, in the current board implementation,

is 63.5 dB.

MUTE

Pressing the key marked MUTE causes the mute option to be toggled between on and off. LED (D8)

is illuminated when the WM8816 is muted.

The WM8816 Micro-Controller Board initiates what the data sheet calls a “Software Mute” - since it is

achieved by writing the code for –112dB to the digital serial interface of the WM8816 chip.

It is still possible to adjust the volume, balance and peak level detection settings whilst the device is

muted. However it should be noted that these settings will only come into effect once the device is

un-muted.

w

Rev 1.1, December 2002

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