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#include "systick.h"
systick_t *get_systick() {
return (systick_t *) 0xE000E010;
}
// This function is to Initialize SysTick registers
void init_systick()
{
// Use the SysTick global structure pointer to do the following in this
// exact order with separate lines for each step:
//
// Disable SysTick by clearing the CTRL (CSR) register.
// Set the LOAD (RVR) to 8 million to give us a 100 milliseconds timer.
// Set the clock source bit in the CTRL (CSR) to the internal clock.
// Set the enable bit in the CTRL (CSR) to start the timer.
systick_t *s = get_systick();
s->CSR &= ~1;
s->CSR |= 1<<2;
s->CSR |= 1<<1; // enable interrupt
s->RVR = 78124; // 100 ms
s->CSR |= 1;
}
// This fuction is to create delay using SysTick timer counter
void delay_systick()
{
// Using the SysTick global structure pointer do the following:
// Create a for loop that loops 10 times
// Inside that for loop check the COUNTFLAG bit in the CTRL (CSR)
// register in a loop. When that bit is set exit this inner loop
// to do another pass in the outer loop of 10.
systick_t *s = get_systick();
for (int i = 0; i < 10; i++) {
while (~s->CSR & (1<<16))
;
}
}
int check_systick() {
static int i = 0;
systick_t *s = get_systick();
if (!(~s->CSR & (1<<16))) {
i++;
}
if (i >= 10) {
i = 0;
return 1;
} else {
return 0;
}
}
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