c - Arduino:union/struct 属性返回错误值

Question

我正在尝试使用 union 和结构来表示将通过 433Mhz radio 发射器发送的 32 位信号。我在让 Arduino 将 26 位远程 ID 存储在 signal.parts.remote 属性上时遇到问题。当我将其设置为 23607301(十进制)后获取该值时，我得到的是 14341(十进制)。我应该如何构建这个 union 才能让它返回正确的值？

信号.h

union signal_union
{
    struct
    {
        unsigned unit   :2;
        unsigned channel:2;
        unsigned status :1;
        unsigned group  :1;
        unsigned remote :26;
    } parts;
    unsigned long data;
};

typedef union signal_union Signal;

结构测试.ino

#include "Signal.h"

Signal signal1;
Signal signal2;

void testPassingStruct(Signal *variable)
{
    variable->parts.status = 1;

    Serial.print("Unit: ");
    Serial.println(variable->parts.unit);
    Serial.println("Should be: 2");
    Serial.println("");
    Serial.print("Status: ");
    Serial.println(variable->parts.status);
    Serial.println("Should be: 1");
    Serial.println("");
    Serial.print("Remote: ");
    Serial.println(variable->parts.remote);
    Serial.println("Should be: 23607301");
    Serial.println("");
    Serial.print("Data: ");
    Serial.println(variable->data, BIN);
    Serial.println("Should be: 01011010000011100000000101110010");
    Serial.println("");
}

void setup() 
{
    Serial.begin(115200);

    signal1.parts.remote = 23607301;
    signal1.parts.unit = 2;
    signal1.parts.group = 1;
    testPassingStruct(&signal1);
}

void loop() 
{
}

输出(来自 Arduino):

Unit: 2
Should be: 2

Status: 1
Should be: 1

Remote: 14341
Should be: 23607301

Data: 1110000000010100110010
Should be: 01011010000011100000000101110010

这是关于 Arduino: cannot pass union struct as pointer ac I can with gcc compiler 的后续问题

Answer 1

我怀疑问题与 unsigned(又名 unsigned int)是 16 位宽有关。尝试将 remote 字段更改为 unsigned long:

unsigned long remote :26;