1 | #include <stm32f30x.h>
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2 | #include <stm32f30x_gpio.h>
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3 | #include <stm32f30x_rcc.h>
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4 | #include <stm32f30x_usart.h>
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5 | #include <stm32f30x_misc.h>
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6 |
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7 |
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8 |
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9 | //global variables
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10 | volatile unsigned char uart_receive; // for receiving one char
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11 |
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12 |
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13 | // prototypes
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14 | unsigned char USART_ReadByteSync(USART_TypeDef *USARTx);
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15 | void USART2_IRQHandler(void);
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16 | void InitializeUSART();
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17 | int _write (char *pBuffer, int size);
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18 |
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19 |
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20 | void InitializeUSART()
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21 | {
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22 | RCC_USARTCLKConfig(RCC_USART2CLK_SYSCLK);
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23 | RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOB, ENABLE);
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24 | RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE); //Enable peripheral clock for USART2
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25 |
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26 |
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27 | GPIO_InitTypeDef gpioConfig;
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28 |
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29 | //PB3 = USART2.TX => Alternative Function Output
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30 | GPIO_PinAFConfig(GPIOB, GPIO_PinSource3, GPIO_AF_7); //Alternativ Funktionalität USART2 für Pin 3 an GPIOB aktivieren
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31 | gpioConfig.GPIO_Mode = GPIO_Mode_AF; // Alternate function mode page: 237
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32 | gpioConfig.GPIO_OType = GPIO_OType_PP; // Output Push-Pull page: 237
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33 | gpioConfig.GPIO_Speed = GPIO_Speed_10MHz; // Medium speed page: 238
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34 | gpioConfig.GPIO_PuPd = GPIO_PuPd_NOPULL; // No pull-up, pull down page: 239
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35 | gpioConfig.GPIO_Pin = GPIO_Pin_3;
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36 | GPIO_Init(GPIOB, &gpioConfig); // pin initialization
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37 |
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38 |
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39 | //PB4 = USART2.RX => Alternative Function Output
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40 | GPIO_PinAFConfig(GPIOB, GPIO_PinSource4, GPIO_AF_7);
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41 | gpioConfig.GPIO_Mode = GPIO_Mode_AF;
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42 | gpioConfig.GPIO_OType = GPIO_OType_PP;
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43 | gpioConfig.GPIO_Speed = GPIO_Speed_10MHz;
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44 | gpioConfig.GPIO_PuPd = GPIO_PuPd_NOPULL;
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45 | gpioConfig.GPIO_Pin = GPIO_Pin_4;
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46 | GPIO_Init(GPIOB, &gpioConfig);
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47 |
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48 |
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49 | USART_InitTypeDef usartConfig;
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50 |
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51 | usartConfig.USART_BaudRate = 9600;
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52 | usartConfig.USART_WordLength = USART_WordLength_8b; //USART2->CR1 |= 0x0000;
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53 | usartConfig.USART_StopBits = USART_StopBits_1;
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54 | usartConfig.USART_Parity = USART_Parity_No;
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55 | usartConfig.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
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56 | usartConfig.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
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57 | USART_Init(USART2, &usartConfig);
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58 |
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59 |
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60 |
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61 | // ######## configure NVIC for Interrupt when data received: ###########
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62 | NVIC_InitTypeDef NVIC_InitStructure;
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63 |
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64 | NVIC_InitStructure.NVIC_IRQChannel = USART2_IRQn; // select NVIC channel
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65 | NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0; // value between 0 and 15; A lower priority value indicates a higher priority
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66 | NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
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67 | NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
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68 | NVIC_Init(&NVIC_InitStructure);
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69 | USART_ClearITPendingBit(USART2, USART_IT_RXNE); // Clear interrupt flag
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70 | USART_ClearITPendingBit(USART2, USART_IT_TXE);
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71 |
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72 | USART_ITConfig(USART2, USART_IT_TXE, DISABLE); // disable Transmit Data Register empty interrupt
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73 | USART_ITConfig(USART2, USART_IT_RXNE, ENABLE); // Enable the USART RX Interrupt
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74 | //NVIC_EnableIRQ(USART2_IRQn); // Enable USART2 global interrupt
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75 |
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76 |
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77 | USART_Cmd(USART2, ENABLE); // UART2 enable //USARTx->CR1 |= USART_CR1_UE; //Enable the selected USART by setting the UE bit in the CR1 register */ page: 937
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78 | }
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79 |
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80 |
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81 |
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82 | void USART2_IRQHandler(void)
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83 | {
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84 | //Interrupt handler implementation
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85 |
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86 | if (USART_GetITStatus(USART2, USART_IT_RXNE)) //checking if interrupt
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87 | uart_receive = USART_ReadByteSync(USART2);
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88 |
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89 | USART_ClearITPendingBit(USART2, USART_IT_RXNE); //Clear interrupt flag
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90 | }
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91 |
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92 |
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93 |
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94 | unsigned char USART_ReadByteSync(USART_TypeDef *USARTx)
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95 | {
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96 | while (USART_GetFlagStatus(USARTx, USART_FLAG_RXNE) == RESET) // RXNE is set when content of the shift register is transferred to the RDR
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97 | {
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98 |
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99 | }
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100 |
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101 | return (unsigned char)USART_ReceiveData(USARTx);
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102 | }
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103 |
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104 |
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105 |
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106 | int main ()
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107 | {
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108 |
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109 | SystemInit();
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110 | InitializeUSART();
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111 |
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112 | for (;;)
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113 | {
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114 | while(1)
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115 | {
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116 | //for sending 1 char
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117 | while(USART_GetFlagStatus(USART2, USART_FLAG_TXE) == RESET); // we can only write in the TDR register when TXE=1 (because when TXE ==1 -> data is transferred to the shift register) page: 898 - 899
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118 | {
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119 | USART_SendData(USART2, 0x55); //USARTx->TDR = (Data & (uint16_t)0x01FF); //Transmit data by writing it in the TDR
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120 | }
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121 |
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122 |
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123 | }
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124 | }
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125 | }
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