system_clock.c¶

Detailed Description¶

Author: Charliechen114514 (chengh1922@mails.jlu.edu.cn)

Version: 0.1

Date: 2025-03-30

Source code¶

#include "system_clock.h"

#include "app.h"
#include "cfbd_define.h"
#include "config/system_settings.h"

void system_delay_us(uint32_t us)
{
    CFBDApplication* app = getApp(CFBD_FALSE);

    uint64_t ticks; // Total number of ticks required for the delay
    uint32_t prevValue, currentValue,
            elapsedTicks = 0;             // Variables for SysTick counter values and elapsed ticks
    uint32_t reloadValue = SysTick->LOAD; // Value of the SysTick reload register
    uint32_t sysclk_freq = app->freq_provider() / 1000000L;
    ticks = us * sysclk_freq; // Calculate the number of ticks needed for the desired delay in
                              // microseconds

    prevValue = SysTick->VAL; // Store the initial SysTick counter value

    while (1) {
        currentValue = SysTick->VAL; // Get the current SysTick counter value
        if (currentValue != prevValue) {
            if (currentValue < prevValue) {
                elapsedTicks +=
                        prevValue -
                        currentValue; // Count the elapsed ticks (SysTick is a decrementing counter)
            }
            else {
                elapsedTicks += reloadValue - currentValue + prevValue; // Handle the rollover case
            }
            prevValue = currentValue; // Update the previous value to the current value

            if (elapsedTicks >=
                ticks) // If the elapsed time is greater than or equal to the requested delay
            {
                break; // Exit the loop to complete the delay
            }
        }
    }
}

void system_delay_ms(uint32_t delay_ms)
{
    for (uint32_t i = 0; i < delay_ms; i++) {
        system_delay_us(1000);
    }
}

Updated on 2026-02-03 at 13:21:55 +0000