如何只用寄存器修改波特率

247470035 · 发表于 2019-10-15 18:05:17

void usart1_init(void)
{
GPIO_InitTypeDef GPIO_InitStruct;
USART_InitTypeDef USART_InitStruct;
NVIC_InitTypeDef NVIC_InitStruct;

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);

GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_InitStruct.GPIO_Pin = GPIO_Pin_9;
GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOA, &GPIO_InitStruct);

GPIO_InitStruct.GPIO_Mode = GPIO_Mode_IPD;
GPIO_InitStruct.GPIO_Pin = GPIO_Pin_10;
GPIO_Init(GPIOA, &GPIO_InitStruct);

//USART_InitStruct.USART_BaudRate = 2482758;
//USART1->BRR = 29;
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USART1->BRR = 0x1d;
USART_InitStruct.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
USART_InitStruct.USART_Mode = USART_Mode_Tx | USART_Mode_Rx;
USART_InitStruct.USART_Parity = USART_Parity_No;
USART_InitStruct.USART_StopBits = USART_StopBits_1;
USART_InitStruct.USART_WordLength = USART_WordLength_8b;
USART_Init(USART1, &USART_InitStruct);

NVIC_InitStruct.NVIC_IRQChannel = USART1_IRQn;
NVIC_InitStruct.NVIC_IRQChannelCmd = ENABLE;
NVIC_InitStruct.NVIC_IRQChannelPreemptionPriority = 0;
NVIC_InitStruct.NVIC_IRQChannelSubPriority = 1;
NVIC_Init(&NVIC_InitStruct);

USART_ITConfig(USART1, USART_IT_RXNE, ENABLE);
USART_Cmd(USART1, ENABLE);
}

如分界线下部，库函数和寄存器混合操作，将波特率寄存器设置为“USART1->BRR = 0x1d”，上面是我自己写的例程，但是寄存器没有设置成功，不用库函数设置是因为波特率是一个特殊值，用库函数设置误码太大，只能操作寄存器。操作平台：stm32f103系列。

目标任务：将波特率寄存器设置为“ USART1->BRR = 0x1d ”