Commit 522bd7b3 authored by Jan Kasprzak's avatar Jan Kasprzak
Browse files

pwm.c: switch off PLL when not needed

parent ab58f34d

projects/step-up/pwm.c

+15 −6
Original line number Diff line number Diff line
@@ -11,10 +11,12 @@ 
 * Counts from 0 to 0xFF, without OCR1C compare.

 */



static unsigned char pwm_enabled;



static void inline enable_pll()

{

	/* Async clock */

	PLLCSR = _BV(PLLE);

	PLLCSR = _BV(PLLE) | _BV(LSM);



	/* Synchronize to the phase lock */

	_delay_us(100);
@@ -25,17 +27,16 @@ static void inline enable_pll() 


void init_pwm()

{

	pwm_enabled = 0;

	power_timer1_enable();



	enable_pll();



	TCCR1 = _BV(CTC1) | _BV(CS10);	// no clock prescaling

	TCCR1 = _BV(CTC1) | _BV(CS11);	// pll_clk/2

	GTCCR = _BV(COM1B1) | _BV(PWM1B);



	OCR1C = PWM_MAX;

	OCR1B = 0;		// initial stride is 0



	DDRB  &= ~_BV(PB4); // tristate it

	DDRB &= ~(_BV( PB4 ));

	PORTB &= ~_BV(PB4); // set to zero

}
@@ -54,10 +55,18 @@ void pwm_off() 
{

	OCR1B = 0;

	DDRB &= ~_BV(PB4);



	PLLCSR &= ~(_BV(PLLE) | _BV(PCKE));

	pwm_enabled = 0;

}



void pwm_set(uint8_t stride)

{

	OCR1B = stride;



	if (!pwm_enabled) {

		enable_pll();

		DDRB |= _BV(PB4);

		pwm_enabled = 1;

	}

}