ad1988a Analog Devices, Inc., ad1988a Datasheet - Page 19
ad1988a
Manufacturer Part Number
ad1988a
Description
High Definition Audio Soundmax Codec
Manufacturer
Analog Devices, Inc.
Datasheet
1.AD1988A.pdf
(20 pages)
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HARDWARE VOLUME CONTROL
The AD1988A/AD1988B support external volume control on
Pin 2 (GPIO_0/VOLUME). The circuit diagram in Figure 4
allows up/down/mute control using only three switches and
four resistors external to the codec. The up/down switches can
also be replaced by a center-position-off SPDT toggle switch.
The mute switch is optional, but desirable, for a satisfactory user
interface.
VDD
R1
3.3kΩ
R2
10kΩ
SW1
UP
Figure 4 . Volume Control Circuitry
R3
5.1kΩ
SW2
DOWN
R4
3.3kΩ
SW3
MUTE
OPTIONAL
GPIO_0/VOLUME
Rev. 0 | Page 19 of 20
To use the GPIO_0/VOLUME pin (Pin 2) as a GPIO pin, it is
recommended to pull it down using a 10 kΩ resistor (Pin 2 to
DV
has no effect.
When the GPIO_0/VOLUME pin (Pin 2) is used as a volume con-
trol, pull-up Pin 2 to AV
the codec volumes only under software control. If one of the
buttons is pressed, the control volume setting is incremented
(up), decremented (down), or set Bit 7 (mute). The volume
control supports 40 steps (other than mute) and uses a range of
0 (0x00, minimum volume) to 63 (0x3F, maximum volume).
Pressing the mute switch (or both up and down simultaneously)
toggles Bit 7 which indicates mute on/off.
SS
). In the GPIO configuration, the volume control widget
DD
. The volume control widget operates
AD1988A/AD1988B