Low frequency oscilloscope. The bandwidth is about 30 to 5000 Hz, the narrow bandwidth and input filter makes the use limited. The mic ADC sends packets of 2048 bytes and 60 bytes are used to draw the trace.
Input is to the microphone socket. Input voltage divider allows signals of 5V P-P. Alternative way is to use an existing headset and connect the input in place of the mic. When no input plugged in the scope shows the signal from the internal mic. The 18-22 ohm resistors simulate speakers, it lets the device switch to external mic.
8.1.2023 The layout scaling was corrected and runtime permission was added so it can work on newer phones.
Input is to the microphone socket. Input voltage divider allows signals of 5V P-P. Alternative way is to use an existing headset and connect the input in place of the mic. When no input plugged in the scope shows the signal from the internal mic. The 18-22 ohm resistors simulate speakers, it lets the device switch to external mic.
8.1.2023 The layout scaling was corrected and runtime permission was added so it can work on newer phones.
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