标签: re-mapping

Pin Re-mapping is a simple but important skills in programming STM32. Here shows a simple example to re-map USART1_TX and USART1_RX from PA9, PA10 (not Five-volt tolerant) to PB6, PB7 (Five-volt tolerant) for STM32F103RB. Comparisons between the steps in re-mapping and not re-mapping the pins When PA9, PA10 are used for USART1 i. Turn on Peripheral Clock for GPIOA ii. Config PA9 as Alternate Function Push-pull output, and PA10 as Input Floating iii. Turn on Peripheral Clock for USART1 iv. Config USART1 baud rate and properties... When PB6, PB7 are used for USART1 (Re-mapping) i. Turn on Peripheral Clock for GPIOB ii. Config PA6 as Alternate Function Push-pull output, and PA7 as Input Floating iii. Turn on Peripheral Clock for USART1 iv. Config USART1 baud rate and properties... v. Enable Alternate Function Clock vi. Enable USART1 re-mapping From above, we can see that only two more steps is needed... It is so simple! Sample Coding for re-mapping the USART1: ---------------------------------------------------- GPIO_InitTypeDef GPIO_InitStructure; USART_InitTypeDef USART_InitStructure; /* Turn on periph clock for both GPIOB and USART */ RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB | RCC_APB2Periph_USART1, ENABLE); /* Config GPIO */ GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6;              GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP; GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;   GPIO_Init(GPIOB, GPIO_InitStructure);            GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7;             GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;   GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; GPIO_Init(GPIOB, GPIO_InitStructure); /* Config USART1 */    USART_InitStructure.USART_BaudRate = 115200; USART_InitStructure.USART_WordLength = USART_WordLength_8b; USART_InitStructure.USART_StopBits = USART_StopBits_1; USART_InitStructure.USART_Parity = USART_Parity_No; USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None; USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx; USART_Init(USART1, USART_InitStructure); USART_ITConfig(USART1, USART_IT_RXNE, ENABLE); USART_ITConfig(USART1, USART_IT_TXE, ENABLE); USART_ClearFlag(USART1,USART_FLAG_TC); USART_Cmd(USART1, ENABLE); /* Re-mapping Config */ RCC_APB2PeriphClockCmd( RCC_APB2Periph_AFIO , ENABLE); GPIO_PinRemapConfig(GPIO_Remap_USART1, ENABLE); ---------------------------------------------------- The peripheral clock command of AFIO can be combined with that of GPIOB and USART1, i.e. the re-mapping only requires only 1 more line of code.