Arduino Spy Bug

A simple voice recorder for Arduino using an SD card and an electret microphone amplifier circuit.

Independent of any third-party libraries.

Wiring (also documented in spybug/spybug.ino)

SD Card Wiring

SD	Nano
D0 (DO)	D12 (MISO)
VSS	GND
CLK	D13 (SCK)
VDD	5V or 3V3
CMD (DI)	D11 (MOSI)
D3 (CS)	D10 (SS)

WARNING: SD cards are not designed for 5V; I have been using 5V anyways and everything seems fine, but beware that there is a significant risk of immediate or premature failure when not using a buffer circuit.

SD pin D3 is the chip select pin. It can be set manually in PIN_SS.

Microphone Wiring (MAX9814 w/ electret microphone)

Mic	Nano
VCC	5V
GND	GND
Out	A0

Out defaults to A0 (AdcChannel0), but can be set manually in ADC_CHANNEL.

Power Consumption (Arduino Nano)

Mode	Unmodified	No voltage regulator	No TTL module or voltage regulator
Waiting	~10mA	~5.8mA	~6μA
Recording	~30mA	~25.1mA	~25mA