Implement audio wave generator using the Mbed API

• Theory of analog signal to digital signal conversion
• Common type of digital-to-analog converter(DAC)
• Common types of analog-to-digital converters(ADCs) and their advantages and disadvantages
• Properties of analog-to-digital conversion including range, resolution, quantization and sampling
• Demonstrate use of Mbed API functionality to capture and generate analog signals
• Implement a working microcontroller program