diff options
Diffstat (limited to 'libmaple/systick.c')
-rw-r--r-- | libmaple/systick.c | 54 |
1 files changed, 28 insertions, 26 deletions
diff --git a/libmaple/systick.c b/libmaple/systick.c index b9a52c1..c04f4f3 100644 --- a/libmaple/systick.c +++ b/libmaple/systick.c @@ -26,44 +26,46 @@ * @brief System timer interrupt handler and initialization routines */ -#include "libmaple.h" #include "systick.h" -#define SYSTICK_RELOAD 0xE000E014 // Reload value register -#define SYSTICK_CNT 0xE000E018 // Current value register -#define SYSTICK_CALIB 0xE000E01C // Calibration value register - -#define SYSTICK_SRC_HCLK BIT(2) // Use core clock -#define SYSTICK_TICKINT BIT(1) // Interrupt on systick countdown -#define SYSTICK_ENABLE BIT(0) // Turn on the counter - volatile uint32 systick_timer_millis; +/** + * @brief Initialize and enable SysTick. + * + * Clocks the system timer with the core clock, turns it on, and + * enables interrupts. + * + * @param reload_val Appropriate reload counter to tick every 1 ms. + */ void systick_init(uint32 reload_val) { - /* Set the reload counter to tick every 1ms */ - __write(SYSTICK_RELOAD, reload_val); - - /* Clock the system timer with the core clock and turn it on, - * interrrupt every 1ms to keep track of millis() */ - __write(SYSTICK_CSR, SYSTICK_SRC_HCLK | - SYSTICK_ENABLE | - SYSTICK_TICKINT); + SYSTICK_BASE->RVR = reload_val; + systick_enable(); } +/** + * Clock the system timer with the core clock, but don't turn it + * on or enable interrupt. + */ void systick_disable() { - /* clock the system timer with the core clock, but don't turn it - on or enable interrupt. */ - __write(SYSTICK_CSR, SYSTICK_SRC_HCLK); + SYSTICK_BASE->CSR = SYSTICK_CSR_CLKSOURCE_CORE; } -void systick_resume() { - /* re-enable init registers without changing reload val */ - __write(SYSTICK_CSR, SYSTICK_SRC_HCLK | - SYSTICK_ENABLE | - SYSTICK_TICKINT); +/** + * Clock the system timer with the core clock and turn it on; + * interrupt every 1 ms, for systick_timer_millis. + */ +void systick_enable() { + /* re-enables init registers without changing reload val */ + SYSTICK_BASE->CSR = (SYSTICK_CSR_CLKSOURCE_CORE | + SYSTICK_CSR_ENABLE | + SYSTICK_CSR_TICKINT_PEND); } -/** SysTick interrupt handler. Bumps up the tick counter. */ +/* + * SysTick ISR + */ + void __exc_systick(void) { systick_timer_millis++; } |