-
-/*
- * AltOS always cranks the clock to the max frequency
- */
-void
-ao_clock_init(void)
-{
- /* disable RC clock */
- CLKSEL0 &= ~(1 << RCE);
-
- /* Disable PLL */
- PLLCSR &= ~(1 << PLLE);
-
- /* Enable external clock */
- CLKSEL0 |= (1 << EXTE);
-
- /* wait for external clock to be ready */
- while ((CLKSTA & (1 << EXTON)) == 0)
- ;
-
- /* select external clock */
- CLKSEL0 |= (1 << CLKS);
-
- /* Disable the clock prescaler */
- cli();
- CLKPR = (1 << CLKPCE);
-
- /* Always run the system clock at 8MHz */
-#if AVR_CLOCK > 12000000UL
- CLKPR = 1;
-#else
- CLKPR = 0;
-#endif
- sei();
-
- /* Set up the PLL to use the crystal */
-
- /* Use primary system clock as PLL source */
- PLLFRQ = ((0 << PINMUX) | /* Use primary clock */
- (0 << PLLUSB) | /* No divide by 2 for USB */
- (0 << PLLTM0) | /* Disable high speed timer */
- (0x4 << PDIV0)); /* 48MHz PLL clock */
-
- /* Set the frequency of the crystal */
-#if AVR_CLOCK > 12000000UL
- PLLCSR |= (1 << PINDIV); /* For 16MHz crystal on Teensy board */
-#else
- PLLCSR &= ~(1 << PINDIV); /* For 8MHz crystal on TeleScience board */
-#endif
-
- /* Enable the PLL */
- PLLCSR |= (1 << PLLE);
- while (!(PLLCSR & (1 << PLOCK)))
- ;
-
- set_sleep_mode(SLEEP_MODE_IDLE);
- sleep_enable();
-}