This group contains functions and definitions related to configuring and enabling/disabling on-chip oscillators.

Internal RC-oscillators, external crystal oscillators and external clock generators are supported by this module. What all of these have in common is that they swing at a fixed, nominal frequency which is normally not adjustable.

Example: Enabling an oscillator

The following example demonstrates how to enable the external oscillator on XMEGA A and wait for it to be ready to use. The oscillator identifiers are platform-specific, so while the same procedure is used on all platforms, the parameter to osc_enable() will be different from device to device.

osc_enable(OSC_ID_XOSC);

osc_wait_ready(OSC_ID_XOSC);

Board-specific Definitions

If external oscillators are used, the board code must provide the following definitions for each of those:

BOARD_<osc name>_HZ: The nominal frequency of the oscillator.
BOARD_<osc name>_STARTUP_US: The startup time of the oscillator in microseconds.
BOARD_<osc name>_TYPE: The type of oscillator connected, i.e. whether it's a crystal or external clock, and sometimes what kind of crystal it is. The meaning of this value is platform-specific.

Macros
#define	OSC0_MODE_VALUE OSC_MODE_XTAL_G3
	Board-dependent value written to the MODE bitfield of PM_OSCCTRL(0) More...

#define	OSC0_STARTUP_TIMEOUT 2560
	Number of slow clock cycles to wait for OSC0 to start. More...

#define	OSC0_STARTUP_VALUE OSC_STARTUP_2048
	Board-dependent value written to the STARTUP bitfield of PM_OSCCTRL(0) More...

#define	OSC1_MODE_VALUE UNDEFINED
	Board-dependent value written to the MODE bitfield of PM_OSCCTRL(1) More...

#define	OSC1_STARTUP_TIMEOUT UNDEFINED
	Number of slow clock cycles to wait for OSC1 to start. More...

#define	OSC1_STARTUP_VALUE UNDEFINED
	Board-dependent value written to the STARTUP bitfield of PM_OSCCTRL(1) More...

#define	OSC32_MODE_VALUE OSC32_MODE_XTAL

#define	OSC32_STARTUP_VALUE OSC32_STARTUP_8192

Oscillator Management
static void	osc_wait_ready (uint8_t id)
	Wait until the oscillator identified by id is ready. More...

static void	osc_enable (uint8_t id)
	Enable oscillator id. More...

static void	osc_disable (uint8_t id)
	Disable oscillator id. More...

static bool	osc_is_ready (uint8_t id)
	Determine whether oscillator id is ready. More...

static uint32_t	osc_get_rate (uint8_t id)
	Return the frequency of oscillator id in Hz. More...

Oscillator identifiers
#define	OSC_ID_OSC0 0
	External Oscillator 0. More...

#define	OSC_ID_OSC1 1
	External Oscillator 1. More...

#define	OSC_ID_OSC32 2
	External 32 kHz oscillator. More...

OSC0/OSC1 mode values
#define	OSC_MODE_EXTERNAL AVR32_PM_MODE_EXT_CLOCK
	External clock connected to XIN. More...

#define	OSC_MODE_XTAL_G0 AVR32_PM_MODE_CRYSTAL_G0
	Crystal connected to XIN/XOUT. Use oscillator gain G0 (400 kHz to 900 kHz) More...

#define	OSC_MODE_XTAL_G1 AVR32_PM_MODE_CRYSTAL_G1
	Crystal connected to XIN/XOUT. Use oscillator gain G1 (900 kHz to 3 MHz) More...

#define	OSC_MODE_XTAL_G2 AVR32_PM_MODE_CRYSTAL_G2
	Crystal connected to XIN/XOUT. Use oscillator gain G2 (3 MHz to 8 MHz) More...

#define	OSC_MODE_XTAL_G3 AVR32_PM_MODE_CRYSTAL_G3
	Crystal connected to XIN/XOUT. Use oscillator gain G3 (8 MHz and higher) More...

OSC32 mode values
#define	OSC32_MODE_EXTERNAL AVR32_PM_OSCCTRL32_MODE_EXT_CLOCK
	External clock connected to XIN32. More...

#define	OSC32_MODE_XTAL AVR32_PM_OSCCTRL32_MODE_CRYSTAL
	Crystal connected to XIN32/XOUT32. Use automatic gain control. More...

OSC0/OSC1 startup values
#define	OSC_STARTUP_0 AVR32_PM_OSCCTRL0_STARTUP_0_RCOSC
	0 cycles More...

#define	OSC_STARTUP_64 AVR32_PM_OSCCTRL0_STARTUP_64_RCOSC
	64 cycles (560 us) More...

#define	OSC_STARTUP_128 AVR32_PM_OSCCTRL0_STARTUP_128_RCOSC
	128 cycles (1.1 ms) More...

#define	OSC_STARTUP_2048 AVR32_PM_OSCCTRL0_STARTUP_2048_RCOSC
	2048 cycles (18 ms) More...

#define	OSC_STARTUP_4096 AVR32_PM_OSCCTRL0_STARTUP_4096_RCOSC
	4096 cycles (36 ms) More...

#define	OSC_STARTUP_8192 AVR32_PM_OSCCTRL0_STARTUP_8192_RCOSC
	8192 cycles (71 ms) More...

#define	OSC_STARTUP_16384 AVR32_PM_OSCCTRL0_STARTUP_16384_RCOSC
	16384 cycles (142 ms) More...

OSC32 startup values
#define	OSC32_STARTUP_0 AVR32_PM_OSCCTRL32_STARTUP_0_RCOSC
	0 cycles More...

#define	OSC32_STARTUP_128 AVR32_PM_OSCCTRL32_STARTUP_128_RCOSC
	128 cycles (1.1 ms) More...

#define	OSC32_STARTUP_8192 AVR32_PM_OSCCTRL32_STARTUP_8192_RCOSC
	8192 cycles (72.3 ms) More...

#define	OSC32_STARTUP_16384 AVR32_PM_OSCCTRL32_STARTUP_16384_RCOSC
	16384 cycles (143 ms) More...

#define	OSC32_STARTUP_65536 AVR32_PM_OSCCTRL32_STARTUP_65536_RCOSC
	65536 cycles (570 ms) More...

#define	OSC32_STARTUP_131072 AVR32_PM_OSCCTRL32_STARTUP_131072_RCOSC
	131072 cycles (1.1 s) More...

#define	OSC32_STARTUP_262144 AVR32_PM_OSCCTRL32_STARTUP_262144_RCOSC
	262144 cycles (2.3 s) More...

#define	OSC32_STARTUP_524288 AVR32_PM_OSCCTRL32_STARTUP_524288_RCOSC
	524288 cycles (4.6 s) More...

Board-specific configuration parameters
The following definitions must be provided by the board code for all working oscillators on the board.
#define	BOARD_OSC0_HZ 12000000
	Clock frequency of OSC0 in Hz. More...

#define	BOARD_OSC0_STARTUP_US 17000
	Startup time of OSC0 in microseconds. More...

#define	BOARD_OSC0_IS_XTAL true
	OSC0 uses a crystal, not an external clock. More...

#define	BOARD_OSC1_HZ UNDEFINED
	Clock frequency of OSC1 in Hz. More...

#define	BOARD_OSC1_STARTUP_US UNDEFINED
	Startup time of OSC1 in microseconds. More...

#define	BOARD_OSC1_IS_XTAL UNDEFINED
	OSC1 uses a crystal, not an external clock. More...

#define	BOARD_OSC32_HZ 32768
	Clock frequency of OSC32 in Hz. More...

#define	BOARD_OSC32_STARTUP_US 71000
	Startup time of OSC32 in microseconds. More...

#define	BOARD_OSC32_IS_XTAL true
	OSC32 uses a crystal, not an external clock. More...

Slow clock frequency limits
The slow clock is an internal RC oscillator whose frequency may drift a bit as a result of temperature changes. These definitions provide upper and lower limits which may be used to calculate upper and lower limits of timeouts, derived clock frequencies, etc.
#define	OSC_SLOW_NOMINAL_HZ AVR32_PM_RCOSC_FREQUENCY
	Nominal frequency of the slow clock in Hz. More...

#define	OSC_SLOW_MIN_HZ 100000
	Minimum frequency of the slow clock in Hz. More...

#define	OSC_SLOW_MAX_HZ 120000
	Maximum frequency of the slow clock in Hz. More...

#define BOARD_OSC0_HZ 12000000

Clock frequency of OSC0 in Hz.

Referenced by osc_get_rate(), sysclk_get_main_hz(), and sysclk_init().

#define BOARD_OSC0_IS_XTAL true

OSC0 uses a crystal, not an external clock.

#define BOARD_OSC0_STARTUP_US 17000

Startup time of OSC0 in microseconds.

#define BOARD_OSC1_HZ UNDEFINED

Clock frequency of OSC1 in Hz.

Referenced by osc_get_rate().

#define BOARD_OSC1_IS_XTAL UNDEFINED

OSC1 uses a crystal, not an external clock.

#define BOARD_OSC1_STARTUP_US UNDEFINED

Startup time of OSC1 in microseconds.

#define BOARD_OSC32_HZ 32768

Clock frequency of OSC32 in Hz.

Referenced by osc_get_rate().

#define BOARD_OSC32_IS_XTAL true

OSC32 uses a crystal, not an external clock.

#define BOARD_OSC32_STARTUP_US 71000

Startup time of OSC32 in microseconds.

#define OSC0_MODE_VALUE OSC_MODE_XTAL_G3

Board-dependent value written to the MODE bitfield of PM_OSCCTRL(0)

Referenced by osc_enable().

#define OSC0_STARTUP_TIMEOUT 2560

Number of slow clock cycles to wait for OSC0 to start.

This is the number of slow clock cycles corresponding to OSC0_STARTUP_VALUE with an additional 25% safety margin. If the oscillator isn't running when this timeout has expired, it is assumed to have failed to start.

Referenced by run_osc_test().

#define OSC0_STARTUP_VALUE OSC_STARTUP_2048

Board-dependent value written to the STARTUP bitfield of PM_OSCCTRL(0)

Referenced by osc_enable().

#define OSC1_MODE_VALUE UNDEFINED

Board-dependent value written to the MODE bitfield of PM_OSCCTRL(1)

Referenced by osc_enable().

#define OSC1_STARTUP_TIMEOUT UNDEFINED

Number of slow clock cycles to wait for OSC1 to start.

This is the number of slow clock cycles corresponding to OSC1_STARTUP_VALUE with an additional 25% safety margin. If the oscillator isn't running when this timeout has expired, it is assumed to have failed to start.

Referenced by run_osc_test().

#define OSC1_STARTUP_VALUE UNDEFINED

Board-dependent value written to the STARTUP bitfield of PM_OSCCTRL(1)

Referenced by osc_enable().

#define OSC32_MODE_EXTERNAL AVR32_PM_OSCCTRL32_MODE_EXT_CLOCK

External clock connected to XIN32.

#define OSC32_MODE_VALUE OSC32_MODE_XTAL

Referenced by osc_enable().

#define OSC32_MODE_XTAL AVR32_PM_OSCCTRL32_MODE_CRYSTAL

Crystal connected to XIN32/XOUT32. Use automatic gain control.

#define OSC32_STARTUP_0 AVR32_PM_OSCCTRL32_STARTUP_0_RCOSC

0 cycles

#define OSC32_STARTUP_128 AVR32_PM_OSCCTRL32_STARTUP_128_RCOSC

128 cycles (1.1 ms)

#define OSC32_STARTUP_131072 AVR32_PM_OSCCTRL32_STARTUP_131072_RCOSC

131072 cycles (1.1 s)

#define OSC32_STARTUP_16384 AVR32_PM_OSCCTRL32_STARTUP_16384_RCOSC

16384 cycles (143 ms)

#define OSC32_STARTUP_262144 AVR32_PM_OSCCTRL32_STARTUP_262144_RCOSC

262144 cycles (2.3 s)

#define OSC32_STARTUP_524288 AVR32_PM_OSCCTRL32_STARTUP_524288_RCOSC

524288 cycles (4.6 s)

#define OSC32_STARTUP_65536 AVR32_PM_OSCCTRL32_STARTUP_65536_RCOSC

65536 cycles (570 ms)

#define OSC32_STARTUP_8192 AVR32_PM_OSCCTRL32_STARTUP_8192_RCOSC

8192 cycles (72.3 ms)

#define OSC32_STARTUP_VALUE OSC32_STARTUP_8192

Referenced by osc_enable().

#define OSC_ID_OSC0 0

External Oscillator 0.

Referenced by cleanup_osc_test(), genclk_enable_source(), osc_disable(), osc_enable(), osc_get_rate(), osc_is_ready(), pll_enable_source(), run_osc_test(), and sysclk_init().

#define OSC_ID_OSC1 1

External Oscillator 1.

Referenced by cleanup_osc_test(), genclk_enable_source(), osc_disable(), osc_enable(), osc_get_rate(), osc_is_ready(), pll_enable_source(), and run_osc_test().

#define OSC_ID_OSC32 2

External 32 kHz oscillator.

Referenced by cleanup_osc32_test(), osc_disable(), osc_enable(), osc_get_rate(), osc_is_ready(), and run_osc32_test().

#define OSC_MODE_EXTERNAL AVR32_PM_MODE_EXT_CLOCK

External clock connected to XIN.

#define OSC_MODE_XTAL_G0 AVR32_PM_MODE_CRYSTAL_G0

Crystal connected to XIN/XOUT. Use oscillator gain G0 (400 kHz to 900 kHz)

#define OSC_MODE_XTAL_G1 AVR32_PM_MODE_CRYSTAL_G1

Crystal connected to XIN/XOUT. Use oscillator gain G1 (900 kHz to 3 MHz)

#define OSC_MODE_XTAL_G2 AVR32_PM_MODE_CRYSTAL_G2

Crystal connected to XIN/XOUT. Use oscillator gain G2 (3 MHz to 8 MHz)

#define OSC_MODE_XTAL_G3 AVR32_PM_MODE_CRYSTAL_G3

Crystal connected to XIN/XOUT. Use oscillator gain G3 (8 MHz and higher)

#define OSC_SLOW_MAX_HZ 120000

Maximum frequency of the slow clock in Hz.

#define OSC_SLOW_MIN_HZ 100000

Minimum frequency of the slow clock in Hz.

#define OSC_SLOW_NOMINAL_HZ AVR32_PM_RCOSC_FREQUENCY

Nominal frequency of the slow clock in Hz.

Referenced by sysclk_get_main_hz().

#define OSC_STARTUP_0 AVR32_PM_OSCCTRL0_STARTUP_0_RCOSC

0 cycles

#define OSC_STARTUP_128 AVR32_PM_OSCCTRL0_STARTUP_128_RCOSC

128 cycles (1.1 ms)

#define OSC_STARTUP_16384 AVR32_PM_OSCCTRL0_STARTUP_16384_RCOSC

16384 cycles (142 ms)

#define OSC_STARTUP_2048 AVR32_PM_OSCCTRL0_STARTUP_2048_RCOSC

2048 cycles (18 ms)

#define OSC_STARTUP_4096 AVR32_PM_OSCCTRL0_STARTUP_4096_RCOSC

4096 cycles (36 ms)

#define OSC_STARTUP_64 AVR32_PM_OSCCTRL0_STARTUP_64_RCOSC

64 cycles (560 us)

#define OSC_STARTUP_8192 AVR32_PM_OSCCTRL0_STARTUP_8192_RCOSC

8192 cycles (71 ms)

void osc_disable ( uint8_t id )

inlinestatic

Disable oscillator id.

References cpu_irq_restore(), cpu_irq_save(), OSC_ID_OSC0, OSC_ID_OSC1, and OSC_ID_OSC32.

Referenced by cleanup_osc32_test(), cleanup_osc_test(), and cleanup_pll_dfll_test().

void osc_enable ( uint8_t id )

inlinestatic

Enable oscillator id.

The startup time and mode value is automatically determined based on definitions in the board code.

References cpu_irq_restore(), cpu_irq_save(), OSC0_MODE_VALUE, OSC0_STARTUP_VALUE, OSC1_MODE_VALUE, OSC1_STARTUP_VALUE, OSC32_MODE_VALUE, OSC32_STARTUP_VALUE, OSC_ID_OSC0, OSC_ID_OSC1, and OSC_ID_OSC32.

Referenced by genclk_enable_source(), pll_enable_source(), run_osc32_test(), run_osc_test(), run_pll_dfll_test(), and sysclk_init().

uint32_t osc_get_rate ( uint8_t id )

inlinestatic

Return the frequency of oscillator id in Hz.

References BOARD_OSC0_HZ, BOARD_OSC1_HZ, BOARD_OSC32_HZ, OSC_ID_OSC0, OSC_ID_OSC1, and OSC_ID_OSC32.

Referenced by pll_config_init().

osc_is_ready ( uint8_t id )

inlinestatic

Determine whether oscillator id is ready.

Return values

true	Oscillator id is running and ready to use as a clock source.
false	Oscillator id is not running.

References OSC_ID_OSC0, OSC_ID_OSC1, and OSC_ID_OSC32.

Referenced by genclk_enable_source(), osc_wait_ready(), pll_enable_source(), run_osc32_test(), and run_osc_test().

static void osc_wait_ready ( uint8_t id )

inlinestatic

Wait until the oscillator identified by id is ready.

This function will busy-wait for the oscillator identified by id to become stable and ready to use as a clock source.

Parameters

id	A number identifying the oscillator to wait for.

References osc_is_ready().

Referenced by genclk_enable_source(), pll_enable_source(), run_pll_dfll_test(), and sysclk_init().

Microchip® Advanced Software Framework

Board-specific Definitions

Macros

Oscillator Management

Oscillator identifiers

OSC0/OSC1 mode values

OSC32 mode values

OSC0/OSC1 startup values

OSC32 startup values

Board-specific configuration parameters

Slow clock frequency limits