微控制器位域

发布于 2024-11-03 15:08:14 字数 603 浏览 4 评论 0原文

我正在学习微控制器，但我很难理解如何使用联合来设置 GPIO 端口上的各个位。

typedef union _BYTE
{
    byte _byte;
    struct
    {
        unsigned b0:1;
        unsigned b1:1;
        unsigned b2:1;
        unsigned b3:1;
        unsigned b4:1;
        unsigned b5:1;
        unsigned b6:1;
        unsigned b7:1;
    }Bit;
} BYTE;

我使用上面的方法来访问字节的各个位，但是如何使用它以以下方式分配 io 端口值？

MCF_GPIO_PORTDD.Bit.b0 = 1;

我宁愿不分配 _BYTE 类型，然后将端口分配给它。

#define MCF_GPIO_PORTDD             (*(vuint8 *)(&__IPSBAR[0x100009]))

MCF_GPIO_PORTDD 只是一个内存地址。

原文

I am learning about microcontrollers and I am having difficulty understanding how one would use a union to set individual bits on a gpio port.

typedef union _BYTE
{
    byte _byte;
    struct
    {
        unsigned b0:1;
        unsigned b1:1;
        unsigned b2:1;
        unsigned b3:1;
        unsigned b4:1;
        unsigned b5:1;
        unsigned b6:1;
        unsigned b7:1;
    }Bit;
} BYTE;

I am using the above to gain access to the individual bits of a byte, but how do I use this to assign a io port values in the following manner?

MCF_GPIO_PORTDD.Bit.b0 = 1;

I would rather not allocate a type of _BYTE and then assign the port to that.

#define MCF_GPIO_PORTDD             (*(vuint8 *)(&__IPSBAR[0x100009]))

MCF_GPIO_PORTDD is just a memory address.

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旧人九事 2024-11-10 15:08:14

它将端口指针转换为易失性无符号字符（8 位整数）。您可以为您的类型创建一个类似的宏：

#define PORTDD  (*(volatile BYTE *)(&__IPSBAR[0x100009]))

然后使用 PORTDD.Bit.b0 访问它。请注意，在某些情况下，如果您需要确保在单个寄存器写入中设置（或清除）多个位，则需要直接写入._byte。如果您不命名 Bit（只是将其设为匿名），您的 C 编译器可能会让您将其缩短为 PORTDD.b0。

It's casting the port pointer to a volatile unsigned char (8 bit int). You can make a similar macro for your type:

#define PORTDD  (*(volatile BYTE *)(&__IPSBAR[0x100009]))

and then access it with PORTDD.Bit.b0. Note that in some instances you will need to write ._byte directly if you need to ensure multiple bits are set (or cleared) in a single register write. If you don't name Bit (just make it anonymous) your C compiler may let you shorten that to PORTDD.b0.

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