This document demonstrates the use of the Pulse Width Modulation (PWM) block of the ADSP-21990 to generate three-phase sine-wave patterns. It provides an example of configuring the PWM registers and setting the PWM interrupts.
The document describes an implementation for generating three-phase sine-wave Pulse Width Modulation (PWM) patterns on the ADSP-21990 digital signal processor. It details a library routine that initializes the PWM block, configures interrupts for PWMSYNC and PWMTRIP events, and manages DSP registers such as AR, AYO, 14, MRO, SR, AX0, AF, and PX.
| PWM switching frequency example | 20kHz |
|---|---|
| Fundamental frequency example | 60Hz |
| Crystal clock example | 25MHz |
| Peripheral clock example | 12.5kHz |
| PWM dead time example | 2us |
The macro sets the PWMTRIP interrupt to USRO and the PWMSYNC interrupt to USR1.
The phase angle Theta is incremented such that phase A, B and C are 120° apart.
A smooth transition into full ON or full OFF conditions is ensured to avoid signal conflicts.