nejohnson2
New member
I'm not much of an audio expert and I'm looking for a little advice on an issue. I've connected an ADMP401 MEMS mic to the Teensy 3.2 ADC pin A9 and I'm using the audio library to connect and calculate the RMS value of the incoming signal. The setup works, though the RMS output sits at 0.37 in quiet environments and max output is around 0.80. I expected the min and max values of 0-1 and I'm wondering why this is and how to resolve it.
I see in the Audio System Design documentation that the input signal range is 0 - 1.2v and since the mic specs indicate that the output signal sits at half of the VCC - 1.65v, I'm guessing this is the issue. Is this the case? And why is the input range 0-1.2v when I thought ADC input range is 0-3.3v?
Also, I'm still a bit perplexed on the sample rate and bit depth when using the ADC and/or the audio library. The audio library by default captures at 16bit/44.1k? I've come across the ADC library which enables various settings but I'm wondering if that applies and how to control sample rate and bit depth when using the Audio Library.
Thanks so much for the help!
I see in the Audio System Design documentation that the input signal range is 0 - 1.2v and since the mic specs indicate that the output signal sits at half of the VCC - 1.65v, I'm guessing this is the issue. Is this the case? And why is the input range 0-1.2v when I thought ADC input range is 0-3.3v?
Also, I'm still a bit perplexed on the sample rate and bit depth when using the ADC and/or the audio library. The audio library by default captures at 16bit/44.1k? I've come across the ADC library which enables various settings but I'm wondering if that applies and how to control sample rate and bit depth when using the Audio Library.
Thanks so much for the help!