1 | //-------------------------------------------STM32F4_USART-------------------------------------------------------
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2 |
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3 | /* Beschreibung:
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4 | * Ganze Strings mit Endezeichen werden interruptgesteuert empfangen und dann zurückgesendet.
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5 | */
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6 | /*
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7 |
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8 | Hinweis zum Clock fuer 8MHz Quarz, damit er auf 168MHz läuft (betrifft das stm32F4Discovery):
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9 |
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10 | in der system_stm32f4xx.c muss eingetragen sein:
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11 | PLL_M = 8
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12 |
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13 | in der stm32f4xx.h muss eingetragen sein:
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14 | HSE_VALUE = 8000000
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15 | */
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16 |
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17 | #include "stm32f4xx.h"
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18 | #include "stm32f4xx_gpio.h"
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19 | #include "stm32f4xx_rcc.h"
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20 | #include "misc.h"
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21 | #include "stm32f4xx_usart.h"
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22 |
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23 | #define READ_BUFFER_SIZE 20
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24 |
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25 | volatile char read_buffer[READ_BUFFER_SIZE];
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26 | volatile char read_buffer_single = 0;
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27 | volatile char string_complete = 0;
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28 | volatile int uart_str_count = 0;
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29 |
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30 | void Delay(__IO uint32_t nCount)
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31 | {
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32 | while(nCount--)
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33 | {
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34 | }
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35 | }
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36 |
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37 | void USART_INIT_EXAMPLE(void)
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38 | {
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39 | /* USARTx configured as follow:
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40 | - BaudRate = 19200 baud
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41 | - Word Length = 8 Bits
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42 | - One Stop Bit
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43 | - No parity
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44 | - Hardware flow control disabled (RTS and CTS signals)
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45 | - Receive and transmit enabled
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46 | */
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47 | GPIO_InitTypeDef GPIO_InitStructure;
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48 | USART_InitTypeDef USART_InitStructure;
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49 |
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50 | /* Enable GPIO clock */
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51 | RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOC, ENABLE);
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52 |
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53 | /* Enable UART clock */
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54 | RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART3, ENABLE);
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55 |
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56 | /* Connect PXx to USARTx_Tx*/
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57 | GPIO_PinAFConfig(GPIOC, GPIO_PinSource10, GPIO_AF_USART3);
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58 |
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59 | /* Connect PXx to USARTx_Rx*/
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60 | GPIO_PinAFConfig(GPIOC, GPIO_PinSource11, GPIO_AF_USART3);
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61 |
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62 | /* Configure USART Tx as alternate function */
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63 | GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
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64 | GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
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65 | GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
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66 |
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67 | GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
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68 | GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
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69 | GPIO_Init(GPIOC, &GPIO_InitStructure);
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70 |
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71 | /* Configure USART Rx as alternate function */
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72 | GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
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73 | GPIO_InitStructure.GPIO_Pin = GPIO_Pin_11;
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74 | GPIO_Init(GPIOC, &GPIO_InitStructure);
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75 |
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76 | USART_InitStructure.USART_BaudRate = 19200;
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77 | USART_InitStructure.USART_WordLength = USART_WordLength_8b;
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78 | USART_InitStructure.USART_StopBits = USART_StopBits_1;
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79 | USART_InitStructure.USART_Parity = USART_Parity_No;
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80 | USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
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81 | USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
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82 |
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83 | /* USART configuration */
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84 | USART_Init(USART3, &USART_InitStructure);
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85 |
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86 | // Receive Interrupt enable
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87 | USART_ITConfig(USART3,USART_IT_RXNE,ENABLE);
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88 |
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89 | /* Enable USART */
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90 | USART_Cmd(USART3, ENABLE);
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91 |
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92 | }
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93 |
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94 | void UART_SEND_EXAMPLE(char byte)
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95 | {
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96 | USART_SendData(USART3,byte);
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97 | /* Loop until the end of transmission */
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98 | while (USART_GetFlagStatus(USART3, USART_FLAG_TC) == RESET){}
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99 | }
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100 |
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101 | void UART_SEND_TEXT_EXAMPLE(char *buffer)
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102 | {
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103 | while (*buffer)
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104 | {
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105 | UART_SEND_EXAMPLE(*buffer);
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106 | buffer++;
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107 | }
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108 | }
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109 |
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110 | void NVIC_INIT_EXAMPLE(uint16_t IRQ)
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111 | {
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112 | NVIC_InitTypeDef NVIC_InitStructure;
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113 |
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114 | NVIC_InitStructure.NVIC_IRQChannel = IRQ;
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115 | NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; // IRQ Channel wird enabled
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116 | NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0; // Die Priorität --> kleine Zahlen = hohe Priorität
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117 | NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
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118 | NVIC_Init(&NVIC_InitStructure);
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119 | }
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120 |
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121 | void USART3_IRQHandler(void)
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122 | {
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123 | if (USART_GetITStatus(USART3,USART_IT_RXNE) == SET)
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124 | {
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125 | USART_ClearITPendingBit(USART3,USART_IT_RXNE);
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126 |
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127 | // Daten aus dem Puffer lesen
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128 | read_buffer_single = (USART3->DR & (uint16_t)0x01FF);
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129 |
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130 | if ( string_complete==0 )
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131 | {
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132 | //Bedingungen für ein Ende des Strings
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133 | if (read_buffer_single!='\n' && read_buffer_single!='\r' && uart_str_count<READ_BUFFER_SIZE-1)
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134 | {
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135 | read_buffer[uart_str_count]=read_buffer_single;
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136 | uart_str_count++;
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137 | }
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138 | else
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139 | {
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140 | read_buffer[uart_str_count]='\0';
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141 | uart_str_count=0;
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142 | string_complete=1;
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143 | }
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144 | }
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145 | }
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146 | }
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147 |
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148 |
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149 | int main(void)
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150 | {
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151 |
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152 | // Systemclock auf 168MHz (stm32F4Discovery mit 8MHz Quarz)
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153 | SystemInit();
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154 |
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155 | // Initialisieren der Schnittstelle
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156 | USART_INIT_EXAMPLE();
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157 |
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158 | // Interruptcontroller für RX-Interrupt konfigurieren
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159 | NVIC_INIT_EXAMPLE(USART3_IRQn);
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160 |
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161 |
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162 | //nun Text auf der ser. Schnittstelle empfangen und zurücksenden.
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163 | while(1)
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164 | {
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165 | if (string_complete)
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166 | {
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167 | // Echo des gesendeten Strings erzeugen
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168 | // Achtung der String muss mit '\n' oder '\r' abgeschlossen werden beim Sender
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169 | UART_SEND_TEXT_EXAMPLE((char*)read_buffer);
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170 | string_complete = 0;
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171 | }
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172 | }
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173 | }
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