I am interested in using your Pi Audio Module B (SKU 0102133) for a project and want to add a volume control knob. Is it possible to wire in a potentiometer somewhere in the circuit to control the output audio volume?
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add a volume control knob For Raspberry Pi GPIO audio
2024-04-04 14:06:04 Ask
8answers
SpotPearUser4
- Answer time:
Adjust the voltage at pin 7 (VOLUME). The lower the voltage, the louder the sound becomes.
https://cdn.static.spotpear.com/uploads/picture/forum/240404-3.jpg
You can adjust the volume by varying the voltage of the above pin using a potentiometer.
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SpotPearGuest14b17
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Thanks for your very quick reply. Could you verify what chip is this? I think it says APA2068 but the image is blurry. If so, it seems simple for a pot to provide the range from VDD to GND.
However, in the schematic I see that VOLUME is connected to AUDIO_PWM. What signal is this?
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SpotPearGuest14b17
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Also, where is the closest VDD in the circuit?
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SpotPearGuestf9576
- Answer time:
Yes , APA2068
AUDIO_PWM have connected to GND
You can check from Physical image
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SpotPearGuestf9576
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VDD is 5V which can be from raspberry pi 5V GPIO PIN
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SpotPearGuestf9576
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Thank you for verifying the chip.
In the layout picture, you highlighted that VOL can be connected to GND.
I see in the earlier schematic that VOL is connected to AUDIO_PWM through R25. In the photo of the board's rear, it looks like R25 is unpopulated. Where does AUDIO_PWM come from? If it is connected to a Raspberry PI GPIO and I might be used with a RC circuit to create a DC voltage level for VOL.
Also, could you show in the layout where the closest VDD (+5V) to VOL pads?
Thank you
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SpotPearUser4
- Answer time:
https://cdn.static.spotpear.com/uploads/picture/forum/240404-4.jpg
】You can find 5V from this picture
】AUDIO_PWM is NC
】more information see picture
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SpotPearGuest48b7f
- Answer time:
Thank you very much for the high quality image. It makes it much easier to see.
So in conclusion, 5V is only available on the other side of the chip or from GPIO header directly.
AUDIO_PWM is a floating net and has no connection as the pad show no traces connected to it.
I think that's all I need to know.
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