User Manual

98
Lesson 19 Sound Sensor
Introduction
Sound sensor is a component that receives sound waves and converts them into electrical
signal. It detects the sound intensity in ambient environment like a microphone.
Components
- 1 * Raspberry Pi
- 1 * Breadboard
- 4 * Jumper wires (Male to Male, 2 red and 2 black)
- 1 * Network cable (or USB wireless network adapter)
- 1 * PCF8591
- 1 * Sound sensor module
- 1 * 3-Pin anti-reverse cable
- Several Jumper wires (Male to Female)
Experimental Principle
The microphone on the sensor module can convert audio signals into electrical signals
(analog quantity), then convert analog quantity into digital quantity by PCF8591 and transfer
them to MCU.
LM358 is a dual-channel operational amplifier. It contains two independent, high gain, and
internally compensated amplifiers, but we will only use one of them in this experiment. The
microphone transforms sound signals into electrical signals and then sends out the signals to
pin 2 of LM358 and outputs them to pin 1 (that's, pin SIG of the module) via the external circuit.
Then use PCF8591 to read analog values.
PCF8591 is an 8-bit resolution, 4-channel A/D，1-channel D/A conversion chip. We connect
the output terminal (SIG) to AIN0 of PCF8591 so as to detect the strength of voice signal in a
real-time manner.