Question

STM32结构体问题

struct RS485_Packet
{
U8 Head1; //1//0
U8 Head2; //1//1/
U8 Length; //1//2
U8 Address; //1//3
U8 Channel; //1//4
U8 CMD; //1//5

U8 Data[];
};
main()
{
struct RS485_Packet RS485_Send_Data;
unsigned char *p;
RS485_Send_Data.Head1=0xa5;//0
RS485_Send_Data.Head2=0x5a;//1
RS485_Send_Data.Length=0x09;//2
RS485_Send_Data.Address=0X01;//3
RS485_Send_Data.Channel=0XFF;//4
RS485_Send_Data.CMD=0X03;//5
//RS485_Send_Data.CHK=0X09;//[0]?不能从零开始
RS485_Send_Data.Data[0]=0x00;//6//7
RS485_Send_Data.Data[1]=0x96;//7//8
p=(unsigned char *)& RS485_Send_Data;
for(count=0;count<6;count++)
{
USART_SendData(USARTx,(p[count]));
check+=p[count];
delay_ms(1);
}
for(count=0;count<RS485_Send_Data.Length-6;count++)
{
USART_SendData(USARTx,RS485_Send_Data.Data[count]);

check+=RS485_Send_Data.Data[count];
delay_ms(1);
}
}
为什么RS485_Send_Data.Data[0]读写值错误一直是0x03 只能从Data[1]开始使用使用

Answer 1

这个 _IO 是指静态 volatile uint32_t就是32位无符号整形数
读取SR寄存器的参数,或者可以说是这个IO口现在的状态.

追问

0.0!是不是发错地了