void pwm_channel_set_period_and_duty_cycle( unsigned id, u32 period, u32 duty )
{
// Fix invalid parameters
if ( duty > period ) duty = period;
#if ASYNCHRONOUS_UPDATE
// If the channel is not active...
if ( ( AVR32_PWM.sr & ( 1 << id ) ) == 0 )
{
// ...write directly to the registers
AVR32_PWM.channel[id].cprd = period;
AVR32_PWM.channel[id].cdty = duty;
}
else
{
// ...otherwise we cannot write CPRD directly, but have to update them
// through the update register.
// You can't change both period and duty cycle in one cycle; you have to
// update one, wait for the end of the output waveform and then update the
// other. This means you always get one cycle of junk between one update
// and the other.
// We can only choose whether to output one cycle at the old frequency
// and the new duty cycle or at the old duty cycle and the new frequency.
// In either case we must ensure that duty <= period for the junk cycle.
// So one solution is, if the period decreases, update the duty cycle first
// or if the period increases, update the period first.
if ( period < AVR32_PWM.channel[id].cprd )
{
pwm_channel_set_duty_cycle( id, duty );
pwm_channel_set_period( id, period );
} else {
pwm_channel_set_period( id, period );
pwm_channel_set_duty_cycle( id, duty );
}
}
#else
// No nasty interrupts: just disable, configure and re-enable.
// In practice, it seems you don't even need to disable the channel
// like the User's Guide tells you to, so we don't bother.
{
//int was_enabled = AVR32_PWM.sr & (1 << id);
//if (was_enabled) AVR32_PWM.dis = 1 << id;
AVR32_PWM.channel[id].cprd = period;
AVR32_PWM.channel[id].cdty = duty;
//if (was_enabled) AVR32_PWM.ena = 1 << id;
}
#endif
}
void pwm_channel_configure2(void volatile *channel, pwm_channel_clock_t const clock, pwm_channel_alignment_t const alignment, pwm_channel_polarity_t const polarity, pwm_channel_update_mode_t const update_mode, uint32_t const period, uint32_t const duty_cycle) {
pwm_channel_configure(channel, clock, alignment, polarity, update_mode);
pwm_channel_set_period(channel, period);
pwm_channel_set_duty_cycle(channel, duty_cycle);
}
