1 | #include "stm32f4xx_conf.h"
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2 |
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3 | static uint32_t messwert=0;
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4 | static float frequenz=0;
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5 |
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6 | void init(void)
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7 | {
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8 | GPIO_InitTypeDef GPIO_InitStructure;
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9 | TIM_ICInitTypeDef TIM_ICInitStructure;
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10 | NVIC_InitTypeDef NVIC_InitStructure;
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11 | TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
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12 |
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13 | // Clock Enable
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14 | RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOC, ENABLE);
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15 |
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16 | // Clock enable
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17 | RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);
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18 |
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19 | // Config des Pins als AF-Input
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20 | GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;
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21 | GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
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22 | GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
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23 | GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
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24 | GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
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25 | GPIO_Init(GPIOC, &GPIO_InitStructure);
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26 |
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27 | // Alternative-Funktion mit dem IO-Pin verbinden
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28 | GPIO_PinAFConfig(GPIOC, GPIO_PinSource9, GPIO_AF_TIM3);
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29 |
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30 | TIM_TimeBaseStructure.TIM_Period = 65535;
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31 | TIM_TimeBaseStructure.TIM_Prescaler = 0;
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32 | TIM_TimeBaseStructure.TIM_ClockDivision = 0;
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33 | TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
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34 | TIM_TimeBaseStructure.TIM_RepetitionCounter = 0;
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35 | TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);
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36 |
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37 | // Vorteiler einstellen (83 => 1MHz)
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38 | TIM_PrescalerConfig(TIM3, 1, TIM_PSCReloadMode_Immediate);
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39 |
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40 | // Channel 4
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41 | TIM_ICInitStructure.TIM_Channel = TIM_Channel_4;
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42 | TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Falling;
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43 | TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
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44 | TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;
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45 | TIM_ICInitStructure.TIM_ICFilter = 0x0;
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46 | TIM_ICInit(TIM3, &TIM_ICInitStructure);
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47 |
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48 | // Timer enable
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49 | TIM_Cmd(TIM3, ENABLE);
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50 |
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51 | NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn;
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52 | NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
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53 | NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
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54 | NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
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55 | NVIC_Init(&NVIC_InitStructure);
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56 |
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57 | TIM_ITConfig(TIM3, TIM_IT_CC4, ENABLE);
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58 | }
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59 |
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60 | void TIM3_IRQHandler(void)
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61 | {
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62 | static uint16_t pos=0;
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63 | static uint32_t t1=0;
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64 | static uint32_t t2=0;
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65 |
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66 |
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67 | if(TIM_GetITStatus(TIM3, TIM_IT_CC4) == SET) {
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68 | // Interrupt Flags loeschen
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69 | TIM_ClearITPendingBit(TIM3, TIM_IT_CC4);
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70 |
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71 | if(pos==0) {
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72 | pos=1;
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73 | t1=TIM_GetCapture4(TIM3);
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74 | }
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75 | else {
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76 | t2=TIM_GetCapture4(TIM3);
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77 |
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78 | if(t2>=t1) {
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79 | messwert=t2-t1;
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80 |
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81 | }
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82 | else {
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83 | messwert=(0xFFFF - t1) + t2;
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84 | }
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85 | t1 = t2;
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86 | }
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87 | }
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88 | }
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89 |
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90 | int main(void)
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91 | {
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92 | init();
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93 | SystemInit();
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94 |
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95 | while(1)
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96 | {
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97 | frequenz = 42000000/messwert;
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98 | }
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99 | }
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