PLL Management

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

A PLL will take an input signal (the source), optionally divide the frequency by a configurable divider, and then multiply the frequency by a configurable multiplier.

Some devices don't support input dividers; specifying any other divisor than 1 on these devices will result in an assertion failure. Other devices may have various restrictions to the frequency range of the input and output signals.

Example: Setting up PLL0 with default parameters

The following example shows how to configure and enable PLL0 using the default parameters specified using the configuration symbols listed above.

pll_enable_config_defaults(0); 

To configure, enable PLL0 using the default parameters and to disable a specific feature like Wide Bandwidth Mode (a UC3A3-specific PLL option.), you can use this initialization process.

struct pll_config pllcfg;
if (pll_is_locked(pll_id)) {
   return; // Pll already running
}
pll_enable_source(CONFIG_PLL0_SOURCE);
pll_config_defaults(&pllcfg, 0);
pll_config_set_option(&pllcfg, PLL_OPT_WBM_DISABLE);
pll_enable(&pllcfg, 0);
pll_wait_for_lock(0); 

When the last function call returns, PLL0 is ready to be used as the main system clock source.

Configuration Symbols

Each PLL has a set of default parameters determined by the following configuration symbols in the application's configuration file:

• CONFIG_PLLn_SOURCE: The default clock source connected to the input of PLL n. Must be one of the values defined by the pll_source enum.
• CONFIG_PLLn_MUL: The default multiplier (loop divider) of PLL n.
• CONFIG_PLLn_DIV: The default input divider of PLL n.

These configuration symbols determine the result of calling pll_config_defaults() and pll_get_default_rate().

Data Structures
struct	pll_config
	Hardware-specific representation of PLL configuration. More...

Macros
#define	PLL_TIMEOUT_MS   div_ceil(1000 * (PLL_MAX_STARTUP_CYCLES * 2), OSC_RCSYS_MIN_HZ)
	Number of milliseconds to wait for PLL lock. More...

Enumerations
enum	pll_source {   PLL_SRC_OSC0 = 0,   PLL_SRC_GCLK9 = 1,   PLL_NR_SOURCES }
	PLL clock source. More...

Functions
static void	pll_config_clear_option (struct pll_config *cfg, uint32_t option)
static void	pll_config_init (struct pll_config *cfg, enum pll_source src, uint32_t divide, uint32_t mul)
	The PLL options PLL_OPT_VCO_RANGE_HIGH and PLL_OPT_OUTPUT_DIV will be set automatically based on the calculated target frequency. More...
static void	pll_config_read (struct pll_config *cfg, uint32_t pll_id)
static void	pll_config_set_option (struct pll_config *cfg, uint32_t option)
void	pll_config_write (const struct pll_config *cfg, uint32_t pll_id)
void	pll_disable (uint32_t pll_id)
void	pll_enable (const struct pll_config *cfg, uint32_t pll_id)
static void	pll_enable_config_defaults (uint32_t pll_id)
static bool	pll_is_locked (uint32_t pll_id)

Chip-specific PLL characteristics
#define	PLL_MAX_STARTUP_CYCLES   (SCIF_PLL_PLLCOUNT_Msk >> SCIF_PLL_PLLCOUNT_Pos)
	Maximum PLL startup time in number of slow clock cycles. More...
#define	NR_PLLS   1
	Number of on-chip PLLs. More...
#define	PLL_MIN_HZ   40000000
	Minimum frequency that the PLL can generate. More...
#define	PLL_MAX_HZ   240000000
	Maximum frequency that the PLL can generate. More...

PLL configuration
#define	pll_config_defaults(cfg, pll_id)
	Initialize PLL configuration using default parameters. More...
#define	pll_get_default_rate(pll_id)
	Get the default rate in Hz of pll_id. More...

Interaction with the PLL hardware
static int	pll_wait_for_lock (unsigned int pll_id)
	Wait for PLL pll_id to become locked. More...
static void	pll_enable_source (enum pll_source src)
	Enable the source of the pll. More...

Chip-specific PLL options
#define	PLL_NR_OPTIONS   3
	Number of PLL option bits. More...
#define	PLL_OPT_VCO_RANGE_HIGH   0
	VCO frequency range is 160-240 MHz (80-180 MHz if unset). More...
#define	PLL_OPT_OUTPUT_DIV   1
	Divide output frequency by two. More...
#define	PLL_OPT_WBM_DISABLE   2
	Disable wide-bandwidth mode. More...
#define	PLL_VCO_LOW_THRESHOLD
	The threshold above which to set the PLL_OPT_VCO_RANGE_HIGH option. More...

#define NR_PLLS   1

Number of on-chip PLLs.

Referenced by pll_config_read(), pll_config_write(), pll_disable(), pll_enable(), pll_is_locked(), and pll_wait_for_lock().

#define pll_config_defaults	(		cfg,
			pll_id
	)

Value:

pll_config_init(cfg,                 \
        CONFIG_PLL ## pll_id ## _SOURCE, \
        CONFIG_PLL ## pll_id ## _DIV,    \
        CONFIG_PLL ## pll_id ## _MUL)

Initialize PLL configuration using default parameters.

After this function returns, cfg will contain a configuration which will make the PLL run at (CONFIG_PLLx_MUL / CONFIG_PLLx_DIV) times the frequency of CONFIG_PLLx_SOURCE.

Parameters

cfg	The PLL configuration to be initialized.
pll_id	Use defaults for this PLL.

#define pll_get_default_rate

(

pll_id

)

Value:

((osc_get_rate(CONFIG_PLL ## pll_id ## _SOURCE) \
    * CONFIG_PLL ## pll_id ## _MUL)                 \
    / CONFIG_PLL ## pll_id ## _DIV)

Get the default rate in Hz of pll_id.

Referenced by sysclk_get_main_hz().

#define PLL_MAX_HZ   240000000

Maximum frequency that the PLL can generate.

Referenced by pll_config_init().

#define PLL_MAX_STARTUP_CYCLES   (SCIF_PLL_PLLCOUNT_Msk >> SCIF_PLL_PLLCOUNT_Pos)

Maximum PLL startup time in number of slow clock cycles.

Referenced by pll_config_init().

#define PLL_MIN_HZ   40000000

Minimum frequency that the PLL can generate.

Note

The PLL must run at twice this frequency internally, but the output frequency may be divided by two by setting the PLLOPT[1] bit.

Referenced by pll_config_init().

#define PLL_NR_OPTIONS   3

Number of PLL option bits.

Number of PLL options.

Referenced by pll_config_clear_option(), and pll_config_set_option().

#define PLL_OPT_OUTPUT_DIV   1

Divide output frequency by two.

Referenced by pll_config_init().

#define PLL_OPT_VCO_RANGE_HIGH   0

VCO frequency range is 160-240 MHz (80-180 MHz if unset).

Referenced by pll_config_init().

#define PLL_OPT_WBM_DISABLE   2

Disable wide-bandwidth mode.

#define PLL_TIMEOUT_MS   div_ceil(1000 * (PLL_MAX_STARTUP_CYCLES * 2), OSC_RCSYS_MIN_HZ)

Number of milliseconds to wait for PLL lock.

#define PLL_VCO_LOW_THRESHOLD

Value:

((SCIF_PLL0_VCO_RANGE1_MIN_FREQ \
    + SCIF_PLL0_VCO_RANGE0_MAX_FREQ) / 2)

The threshold above which to set the PLL_OPT_VCO_RANGE_HIGH option.

Referenced by pll_config_init().

enum pll_source

PLL clock source.

Enumerator
PLL_SRC_OSC0	Oscillator 0.
PLL_SRC_GCLK9	Generic Clock 9.
PLL_NR_SOURCES	Number of PLL sources.

static void pll_config_clear_option ( struct pll_config *  cfg, uint32_t  option  )

inlinestatic

References Assert, pll_config::ctrl, and PLL_NR_OPTIONS.

static void pll_config_init ( struct pll_config *  cfg, enum pll_source  src, uint32_t  divide, uint32_t  mul  )

inlinestatic

The PLL options PLL_OPT_VCO_RANGE_HIGH and PLL_OPT_OUTPUT_DIV will be set automatically based on the calculated target frequency.

References Assert, pll_config::ctrl, DIV_MAX, DIV_MIN, MUL_MAX, MUL_MIN, osc_get_rate(), pll_config_set_option(), PLL_MAX_HZ, PLL_MAX_STARTUP_CYCLES, PLL_MIN_HZ, PLL_NR_SOURCES, PLL_OPT_OUTPUT_DIV, PLL_OPT_VCO_RANGE_HIGH, and PLL_VCO_LOW_THRESHOLD.

Referenced by pll_enable_config_defaults().

static void pll_config_read ( struct pll_config *  cfg, uint32_t  pll_id  )

inlinestatic

References Assert, pll_config::ctrl, and NR_PLLS.

static void pll_config_set_option ( struct pll_config *  cfg, uint32_t  option  )

inlinestatic

References Assert, pll_config::ctrl, and PLL_NR_OPTIONS.

Referenced by pll_config_init().

void pll_config_write	(	const struct pll_config *	cfg,
		uint32_t	pll_id
	)

References Assert, cpu_irq_restore(), cpu_irq_save(), pll_config::ctrl, NR_PLLS, and SCIF_UNLOCK_PLL_REG.

void pll_disable

(

uint32_t

pll_id

)

References Assert, cpu_irq_restore(), cpu_irq_save(), NR_PLLS, and SCIF_UNLOCK_PLL_REG.

void pll_enable	(	const struct pll_config *	cfg,
		uint32_t	pll_id
	)

References Assert, cpu_irq_restore(), cpu_irq_save(), pll_config::ctrl, NR_PLLS, and SCIF_UNLOCK_PLL_REG.

Referenced by pll_enable_config_defaults().

static void pll_enable_config_defaults ( uint32_t  pll_id )

inlinestatic

References Assert, pll_config_init(), pll_enable(), pll_enable_source(), and pll_is_locked().

Referenced by genclk_enable_source(), and sysclk_init().

void pll_enable_source ( enum pll_source  src )

inlinestatic

Enable the source of the pll.

The source is enabled, if the source is not already running.

Parameters

src	The ID of the PLL source to enable.

References Assert, osc_enable(), OSC_ID_OSC0, osc_is_ready(), osc_wait_ready(), PLL_SRC_GCLK9, and PLL_SRC_OSC0.

Referenced by pll_enable_config_defaults().

static bool pll_is_locked ( uint32_t  pll_id )

inlinestatic

References Assert, and NR_PLLS.

Referenced by pll_enable_config_defaults(), and pll_wait_for_lock().

static int pll_wait_for_lock ( unsigned int  pll_id )

inlinestatic

Wait for PLL pll_id to become locked.

Todo:

Use a timeout to avoid waiting forever and hanging the system

Parameters

pll_id

The ID of the PLL to wait for.

Return values

STATUS_OK	The PLL is now locked.
ERR_TIMEOUT	Timed out waiting for PLL to become locked.

References Assert, NR_PLLS, and pll_is_locked().