Description

Driver to initalise SysTick peripheral so that a periodic system clock tick interrupt is generated.

File(s):

px_sysclk_init() configures SysTick to expire every 1/PX_SYSCLK_TICKS_PER_SEC second and generate an interrupt during which a clock tick counter is incremented. px_sysclk_get_tick_count() must be called to fetch a copy of the clock tick counter in an interrupt safe way (atomically).

A periodic timeout function can also be called by the system clock timer interrupt, for example a software RTC can be implemented by calling an RTC update function once a second. The period is specified in 'px_sysclk_cfg.h' with PX_SYSCLK_TIMEOUT_PERIOD_TICKS and the function to call with.

See px_systmr.h : Polled software timers which builds on px_sysclk.h : System Clock using a SysTick peripheral to provide multiple software timers. Example:

#include "px_sysclk.h"
#include "px_systmr.h"
#include "px_compiler.h"
 
void px_systmr_test(void)
{
    // Create a timer object
    px_systmr_t tmr;
 
    // Initialise module
    px_sysclk_init();
 
    // Enable interrupts
    px_interrupts_enable();
  
    // Start timer with a 250 ms timeout
    px_systmr_start(&tmr, TMR_MS_TO_TICKS(250));
    
    // Loop forever
    while(true)
    {
        // Wait until timer has expired
        while(!px_systmr_has_expired(&tmr))
        {
            ;
        }
 
        // Restart timer
        px_systmr_restart(&tmr);
        
        // Do someting...
    }
}

Typedefs
typedef uint32_t	px_sysclk_ticks_t
	Size definition of the tick counter. More...

Functions
void	px_sysclk_init (void)
	Start system clock (one clock tick every 1/PX_SYSCLK_TICKS_PER_SEC seconds) More...

px_sysclk_ticks_t	px_sysclk_get_tick_count (void)
	Return number of ticks since system clock started. More...

void	px_sysclk_reset_tick_count (void)
	Reset tick count. More...

Typedef Documentation

◆ px_sysclk_ticks_t

typedef uint32_t px_sysclk_ticks_t

Size definition of the tick counter.

Definition at line 74 of file px_sysclk.h.

Function Documentation

◆ px_sysclk_init()

void px_sysclk_init ( void )

Start system clock (one clock tick every 1/PX_SYSCLK_TICKS_PER_SEC seconds)

Definition at line 79 of file px_sysclk.c.

◆ px_sysclk_get_tick_count()

px_sysclk_ticks_t px_sysclk_get_tick_count ( void )

Return number of ticks since system clock started.

Returns: px_sysclk_ticks_t Number of clock ticks

Definition at line 97 of file px_sysclk.c.

◆ px_sysclk_reset_tick_count()

void px_sysclk_reset_tick_count ( void )

Reset tick count.

Definition at line 102 of file px_sysclk.c.