今天在调RS485的通信，RE485接GPIOD4口。
用的是串口2的重映射接口。
所以配置串口2重映射，然后模式为USART_HardwareFlowControl_RTS
可是测试的时候，即使是循环发送数据，RTS管脚信号也总是低电平。
PC端通过转的USB口也收不到数据。
如果是不复用RTS信号，将GPIOD4当普通IO口设置高电平就可以正常收发数据。
手动置GPIOD4为高电平则可以发送数据：
#include "stm32f10x.h"
USART_InitTypeDef USART_InitStructure;
GPIO_InitTypeDef GPIO_InitStructure;
int main(void)
{
SystemInit();
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOD|RCC_APB2Periph_AFIO, ENABLE);
RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2,ENABLE);
GPIO_PinRemapConfig(GPIO_Remap_USART2,ENABLE);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_Init(GPIOD, &GPIO_InitStructure);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
GPIO_Init(GPIOD, &GPIO_InitStructure);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
GPIO_Init(GPIOD, &GPIO_InitStructure);
USART_InitStructure.USART_BaudRate =9600;
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_RTS;
USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
USART_Init(USART2, &USART_InitStructure);
USART_Cmd(USART2, ENABLE);
GPIO_SetBits(GPIOD, GPIO_Pin_4);
while(1){
USART_SendData(USART2, 0x41);
while(USART_GetFlagStatus(USART2, USART_FLAG_TXE) == RESET){ }
USART_SendData(USART2, 0x42);
while(USART_GetFlagStatus(USART2, USART_FLAG_TXE) == RESET){ }
}
}
如果使用USART_HardwareFlowControl_RTS，则检测不到RTS电平的变化。PC端也收不到数据。#include "stm32f10x.h"
USART_InitTypeDef USART_InitStructure;
GPIO_InitTypeDef GPIO_InitStructure;
int main(void)
{
SystemInit();
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOD|RCC_APB2Periph_AFIO, ENABLE);
RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2,ENABLE);
GPIO_PinRemapConfig(GPIO_Remap_USART2,ENABLE);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5|GPIO_Pin_4;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_Init(GPIOD, &GPIO_InitStructure);
/*
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
GPIO_Init(GPIOD, &GPIO_InitStructure);
*/
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
GPIO_Init(GPIOD, &GPIO_InitStructure);
USART_InitStructure.USART_BaudRate =9600;
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_RTS;
USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
USART_Init(USART2, &USART_InitStructure);
USART_Cmd(USART2, ENABLE);
// GPIO_SetBits(GPIOD, GPIO_Pin_4);
while(1){
USART_SendData(USART2, 0x41);
while(USART_GetFlagStatus(USART2, USART_FLAG_TXE) == RESET){ }
USART_SendData(USART2, 0x42);
while(USART_GetFlagStatus(USART2, USART_FLAG_TXE) == RESET){ }
}
}
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