Small sketch showing how to use two timers in the Arduino101 (Intel Curie) to generate PWM audio

This module uses two hardware timer/counters. The first timer is configured to generate a pulse-width modulated output (PWM) signal. The second timer is configured as a sample clock: it rolls over and generates an interrupt once every sample period. The interrupt routine fetches the next audio sample and adjusts the duty cycle of the PWM timer.

We use ARC_V2_TRM1 for the sample clock and one of the Quark PWM timers for PWM.

This pencil sketch plays 8KHz 8-bit precomputed samples from in-memory array (sounddata.h). A more comprehensive version would fetch data from an SD card or filesystem.

Modify this to use only Quark timers so audio playback could coexist with PWM generation for servo motors, etc.