I am trying to make a 10 seconds delay function using STM32F4 Discovery board. Unfortunately, it is not working and I don't know why. I have been two days on this problem. Can anyone help me please?

Here is my code:

#include <stm32f4xx_gpio.h>
#include <stm32f4xx_rcc.h>
#include <stm32f4xx_tim.h>

void configLED() {
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);
    GPIO_InitTypeDef GPIO_InitStruct;
    GPIO_InitStruct.GPIO_Pin = GPIO_Pin_13;
    GPIO_InitStruct.GPIO_Mode = GPIO_Mode_OUT;
    GPIO_InitStruct.GPIO_Speed = GPIO_Speed_2MHz;
    GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_NOPULL;
    GPIO_Init(GPIOD, &GPIO_InitStruct);

void configTimerAndGpio() {
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

    GPIO_InitTypeDef GPIO_InitStruct;
    GPIO_InitStruct.GPIO_Pin = GPIO_Pin_3;
    GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF;
    GPIO_InitStruct.GPIO_Speed = GPIO_Speed_2MHz;
    GPIO_InitStruct.GPIO_OType = GPIO_OType_OD;
    GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_NOPULL;
    GPIO_Init(GPIOB, &GPIO_InitStruct);
    GPIO_PinAFConfig(GPIOB, GPIO_Pin_3, GPIO_AF_TIM2);

    //TIM_TimeBaseInitStruct.TIM_Period = 10000;
    TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStruct;
    TIM_TimeBaseInitStruct.TIM_Period = 2000-1;
    TIM_TimeBaseInitStruct.TIM_Prescaler = 21000-1;
    TIM_TimeBaseInitStruct.TIM_ClockDivision = TIM_CKD_DIV1;
    TIM_TimeBaseInitStruct.TIM_CounterMode = TIM_CounterMode_Down;
    TIM_TimeBaseInit(TIM2, &TIM_TimeBaseInitStruct);

void delay() {
    TIM_Cmd(TIM2, ENABLE);
    while (TIM_GetFlagStatus(TIM2, TIM_FLAG_Update) != RESET) {
        TIM_ClearFlag(TIM2, TIM_FLAG_Update);
    //while (TIM_GetCounter(TIM2) > 1) {

int main(void) {
    while (1) {
        GPIO_SetBits(GPIOD, GPIO_Pin_13);
        GPIO_ResetBits(GPIOD, GPIO_Pin_13);
  • 2
    \$\begingroup\$ What are the symptoms? "Is not working" is not sufficient here. What is the expected behavior and the resulting behavior? What oscillator do you use and at which frequency? \$\endgroup\$ – Blup1980 Jun 6 '14 at 9:07

Actually ,i fixed that by using st's clock configuration tool to set the used clock to 84 MHZ then i did some calculation and modified the prescaler.

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On the link below you have tutorial on how to use Systick timer for delay.

Actually, library is written which do that for you.


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  • 1
    \$\begingroup\$ Please post a summary of the details from that link, otherwise the answer will become useless if the link dies. \$\endgroup\$ – PeterJ Jul 7 '14 at 14:16

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