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#include <libopencm3/cm3/nvic.h>
#include <libopencm3/cm3/systick.h>
/* LM3S Specifics, usart and RCC */
#include <libopencm3/lm3s/rcc.h>
#include <libopencm3/lm3s/usart.h>
static volatile uint32_t jiffies = 0u;
static void printbanner(void)
{
char msg[] = "One second elapsed!\r\n";
char *c = msg;
while (*c != 0) {
usart_send(USART0_BASE, (uint16_t )*c);
c++;
}
}
void sys_tick_handler(void)
{
jiffies++;
}
static inline uint32_t systick_app_config(uint32_t n_ticks)
{
/* constant from systick_set_reload -- as this returns something that's
* * not void, this is the only possible error condition */
if (n_ticks & ~0x00FFFFFF) {
return 1;
}
systick_set_reload(n_ticks);
systick_set_clocksource(1);
systick_interrupt_enable();
systick_counter_enable();
return 0;
}
#define HZ 1000
int main(void)
{
uint32_t last_time = 0;
rcc_clock_setup_in_xtal_8mhz_out_50mhz();
systick_app_config(HZ);
nvic_set_priority(NVIC_SYSTICK_IRQ, 0);
jiffies = 0;
while(1) {
if (jiffies > HZ) {
printbanner();
jiffies = 0;
}
}
}
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