1. #include "stm32f4xx.h"
2. #include "stm32f4_discovery.h"
3.  
4. int x;
5. int main(void)
6. {
7.         /*Structures used in the configuration*/
8.   TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
9.   TIM_OCInitTypeDef  TIM_OCInitStructure;
10.   GPIO_InitTypeDef GPIO_InitStructure;
11.  
12.   /* Enable TIM4 Clock */
13.   RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4, ENABLE);
14.  
15.   /* Enable GPIOD Pins that are used for on board LED's */
16.   RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);
17.  
18.   //Enabled GPIOB we are going to use PB6 which is linked to TIM4_CH1 according to the
19.   //documentation
20.  
21.  
22.   /* Initialise  pins 13, 14 and 15 D - relating to on board LED's*/
23.   GPIO_InitStructure.GPIO_Pin = GPIO_Pin_13;
24.   GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
25.   GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
26.   GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
27.   GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP ;
28.   GPIO_Init(GPIOD, &GPIO_InitStructure);
29.  
30.  
31.  
32.   GPIO_PinAFConfig(GPIOD, GPIO_PinSource13, GPIO_AF_TIM4);
33.   /* Setup timer defaults */
34.   TIM_TimeBaseStructure.TIM_Period = 840;//665;
35.   TIM_TimeBaseStructure.TIM_Prescaler = 100;//PrescalerValue;
36.   TIM_TimeBaseStructure.TIM_ClockDivision = 0;
37.   TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
38.  
39.   TIM_TimeBaseInit(TIM4, &TIM_TimeBaseStructure);
40.  
41.  
42.   /* Configure timer for PWM - channel 2 */
43.   TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
44.   TIM_OCInitStructure.TIM_Pulse = 0;
45.   TIM_OC2Init(TIM4, &TIM_OCInitStructure);
46.   TIM_OC2PreloadConfig(TIM4, TIM_OCPreload_Enable);
47.  
48.   /* Configure timer for PWM - channel 3*/
49.  
50.  
51.   /* Configure timer for PWM - channel 4 */
52.  
53.  
54.   TIM_ARRPreloadConfig(TIM4, ENABLE);
55.  
56.   /* Start timer*/
57.   TIM_Cmd(TIM4, ENABLE);
58.  
59.   int power = 0, j=0;
60.   while(1)  //Loop forever
61.   {
62.  
63.           TIM4->CCR2 = 100;//
64.  
65.            x=GPIO_ReadInputDataBit(GPIOD,GPIO_Pin_13);
66.           for(j=0; j<80000; j++);
67.           power++;
68.           if(power > 699){
69.                   power = 0;
70.                   for(j=0; j<80000; j++);
71.           }
72.     }
73. }
74.