如何通过串行发送浮动 [英] How to send float over serial

问题描述

在 Arduino 上通过串行发送 float、double 和 int16 的最佳方式是什么?

What's the best way to send float, double, and int16 over serial on Arduino?

Serial.print() 仅将值作为 ASCII 发送编码.但我想将值作为字节发送.Serial.write() 接受字节和字节数组，但是将值转换为字节的最佳方法是什么?

The Serial.print() only sends values as ASCII encoded. But I want to send the values as bytes. Serial.write() accepts byte and bytearrays, but what's the best way to convert the values to bytes?

我试图将 int16 转换为 byte*，但没有走运.我也使用了 memcpy，但它使用了许多 CPU 周期.Arduino 使用普通的 C/C++.这是一个 ATmega328 微控制器.

I tried to cast an int16 to an byte*, without luck. I also used memcpy, but that uses to many CPU cycles. Arduino uses plain C/C++. It's an ATmega328 microcontroller.

推荐答案

是的，要发送这些数字，您必须先将它们转换为 ASCII 字符串.如果您使用 C，sprintf() 是 IMO 进行此转换的最简便方法:

Yes, to send these numbers you have to first convert them to ASCII strings. If you are working with C, sprintf() is, IMO, the handiest way to do this conversion:

[稍后添加:AAAGHH！我忘记了对于ints/longs，函数的输入参数需要无符号.同样对于传递给 sprintf() 的格式字符串.所以我在下面改变了它.很抱歉我的疏忽，这本来是一个很难找到的错误.此外，ulong 使它更通用一些.]

[Added later: AAAGHH! I forgot that for ints/longs, the function's input argument wants to be unsigned. Likewise for the format string handed to sprintf(). So I changed it below. Sorry about my terrible oversight, which would have been a hard-to-find bug. Also, ulong makes it a little more general.]

char *
int2str( unsigned long num ) {
    static char retnum[21];       // Enough for 20 digits plus NUL from a 64-bit uint.
    sprintf( retnum, "%ul", num );
    return retnum;
}

浮动和双打也类似.进行转换的代码是预先知道的.必须告诉它 - 它正在转换什么样的实体，所以你可能最终得到函数 char *float2str( float float_num) 和 char *dbl2str( double dblnum).

And similar for floats and doubles. The code doing the conversion has be known in advance. It has to be told - what kind of an entity it's converting, so you might end up with functions char *float2str( float float_num) and char *dbl2str( double dblnum).

您将在转换中得到一个以 NUL 结尾的左调整(无前导空格或零)字符串.

You'll get a NUL-terminated left-adjusted (no leading blanks or zeroes) character string out of the conversion.

你可以在任何地方/任何你喜欢的方式进行转换；这些功能只是说明.

You can do the conversion anywhere/anyhow you like; these functions are just illustrations.

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