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 

USING THE PEAK LEVEL DETECTOR

WM8816-MICRO-EV1M

The WM8816 Datasheet describes the full functionality of the peak level detector.

Pressing the key marked “P.REF.” cycles through, on the output display (U2 & U8), all the values

which can be written to the Peak Reference Register (0,1,2….255). Once 255 is reached the display

wraps back round to zero. These values are written instantaneously to the Peak Reference Register.

When the output display (U2 & U8) is showing peak reference information the first letter of the output

display will be a ‘P’ (i.e. P102) and the LED (D5) will be illuminated.

In order to read the information stored in the Peak Status Register the user should press the key

marked “P.STAT”. If the left channel output has exceeded the value held in the Peak Reference

register then the LED (D4) will be illuminated. If the right channel output has exceeded the value

held in the Peak Reference Register then the LED (D2) will be illuminated. If the left or right channel

outputs have not exceeded the value held in the Peak Reference Register then the LED’s (D3 & D1)

are illuminated as appropriate.

Users should be aware that once the output level has exceeded the reference level that the Peak

Status Register will remain set until read (i.e. when the “P.STAT” key is pressed).

Pressing any key, other than “P.STAT” switches off all the Peak Status output LED’s (D1…D4).

TOGGLING THE DISPLAY MODE

Users can toggle between the Volume, Balance, and Peak Reference display modes by pressing the

key marked “DISP.”. This key cycles through the three output display options, without making any

adjustments to the current settings.

The three LED’s in the top right hand corner of the board (D5, D6, and D7) indicate the current

display mode. This can also be deduced from the first letter of the four digit display (U2 & U8).

Volume displays are preceded by either a ‘-‘ sign or blank digit, depending on whether attenuation or

gain is being applied. An ‘L’ or ‘R’ precedes Balance displays’ depending on which channel is

currently louder. Peak Reference displays are preceded by a ‘P’.

SETTING UP A 6 CHANNEL VOLUME CONTROL

It is possible to use more than one WM8816_EV1B board to accommodate a multi-channel system.

The same DATA, and CCLK signals can be used for many WM8816’s with different CSB lines used

to select which chip is currently active.

Figure 6 shows how three WM8816’s can be used with a single Micro-Controller to create a 6

channel volume control.

The three WM8816_EV1B’s should be set up and connected to a ±25V power supply as described in

the “WM8816_EV1BM” user manual. For correct operation it is vital the links on each board are set

up as described in table 1.

The WM8816_EV1B Evaluation Board that is being used to control the front stereo pair of speakers

should have a 10 pin ribbon cable from its serial interface to header J5 on the Micro-controller board,

marked “front”.

Similarly the WM8816_EV1B Evaluation Board that is being used to control the Rear stereo pair of

speakers should have a 10 pin ribbon cable from its serial interface to header J4 on the Micro-

controller board marked “Rear”.

Finally the WM8816_EV1B Evaluation Board that is controlling the Centre & LFE speakers should

have ribbon connection from the serial interface to header J2 on the Micro-Controller board – marked

“Centre / LFE”. This third WM8816_EV1B is slightly different in that it uses its left channel to control

the gain applied to the Centre speaker and its right channel to control the gain applied to the LFE.

Input to the three evaluation boards can come from any 6 channel analogue source; say a DVD

player or the WM8770 Codec.

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Rev 1.1, December 2002

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