Audio with PWM
From ArmadeusWiki
It is possible to generate sound with the APF9328 without any sound chip, just by using the PWM output and the i.MXL possibilities:
Quality
Achieved sound quality is low (8bits @ 8, 16 or 32KHz) but very sufficient to reproduce voice or small sounds. PWM activation/deactivation is generating "clac" each time you play a sound (for the moment) but using some electronic filters or playing "blank noise" could solve the problem.
