PCM Audio

PCM stores sound as a sequence of numeric sample values. Each sample is the amplitude of the waveform at one point in time. If the sample rate is 48 kHz, the device expects 48,000 samples per second for each channel.

Term	Meaning
sample rate	samples per second
channel	mono/stereo layout
frame	one sample per channel
buffer	memory region sent to the device
amplitude	numeric signal level

The device consumes bytes, not musical intent. Your code must translate frequency and duration into sample counts, frame counts, and byte counts. A small mistake in those units can make the audio too short, too long, distorted, or silent.

Square Wave

A square wave alternates between positive and negative amplitude. It is easy to generate and easy to test:

positive for half period
negative for half period
repeat

It is not a beautiful sound, but it is an excellent first waveform because the expected buffer is easy to inspect. Once the square wave works, a sine wave, envelope, melody, or tracker pattern is a higher-level transformation that still ends in PCM samples.