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2022-07-28
Audiohub Nano Analog
User Manual
4.3
Volume Unit (VU) meter display with onboard LEDs
The onboard LEDs turn on based on the measured sound pressure levels (dB SPL). The LEDs work as a volume
unit (VU) meter when streaming the audio data. The threshold for the LED turn-on is based on the sound
pressure level during the audio streaming, as shown in Table 4. In case only one microphone is connected both
LED bars will indicate the volume of the mono audio stream.
Table 4
VU meter setting based on sound pressure level
LED reference
dB SPL
dBFS
LED color
D1, D2
50
-80
green
D3, D4
65
-65
green
D5, D6
80
-50
green
D7, D8
94
-36
yellow
D9, D10
110
-20
orange
D11, D12
125
-5
red
4.4
Operating mode and gain configuration with mode switch
The mode switch push button S1 can be used to switch through various configurations in a sequence. The
settings are defined for configuring the power modes:
•
normal mode
and
•
low power mode
.
The mode switch button also enables different pre-defined gain configurations on the audio data stream. The
gain settings can be configured when the evaluation board is in idle mode and not recording the audio stream.
On power-on, the evaluation board is set to normal mode with 0 dB gain by default. This configuration is
indicated by LED D3.
Table 5 describes the different gain configurations and power modes that can be changed with the mode
switch push button.
Table 5
Operating mode and gain configuration LED reference
LED reference
Operating mode
Gain configuration (dB)
D3
Normal power mode
VDD of microphone at 2.75 V
0
D5
12
D7
18
D9
24
D4
Low power mode
VDD of microphone at 1.60 V
0
D6
12
D8
18
D10
24