27 lines
1.2 KiB
C
27 lines
1.2 KiB
C
#include <stdint.h>
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#include "tm4c123gh6pm.h"
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#define STCTRL *((volatile uint32_t *) 0xE000E010) // Control and status
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#define STRELOAD *((volatile uint32_t *) 0xE000E014) // Reload value
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#define STCURRENT *((volatile uint32_t *) 0xE000E018) // Current value
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#define ENABLE (1 << 0) // Bit 0 of CSR to enable the timer
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#define CLKINT (1 << 2) // Bit 2 of CSR to specify CPU clock
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#define CLOCK_HZ 16000000 // Clock frequency of EK-TM4C123GXL
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#define SYSTICK_RELOAD_VALUE(us) ((CLOCK_HZ / 1000000) * (us) - 1) // SysTick reload value in microseconds based on clock frequency
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void systick_setting(void)
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{
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STRELOAD = SYSTICK_RELOAD_VALUE(1000); // RELOAD VALUE FOR 1ms
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STCTRL |= ENABLE | CLKINT; // Enable SysTick with system clock
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STCURRENT = 0; // Clear current value
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}
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void delay(int us)
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{
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STRELOAD = SYSTICK_RELOAD_VALUE(us); // RELOAD VALUE FOR REQUIRED DELAY
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STCURRENT = 0; // Clear STCURRENT
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STCTRL |= ENABLE | CLKINT; // Enable SysTick
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while ((STCTRL & (1 << 16)) == 0); // Wait until flag is set
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STCTRL &= ~ENABLE; // Stop the timer
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} |