Arduino以太网字节大小问题

发布于 2024-10-10 23:14:04 字数 741 浏览 6 评论 0原文

我使用带有官方以太网扩展板的 Arduino (duemilanove) 将数据发送到控制器以控制 LED 矩阵。我试图通过获取桌面上 32 位值中的 4 个字节并将其作为 4 个连续字节发送到 arduino 来将一些原始 32 位无符号 int 值（unix 时间戳）发送到控制器。但是，每当字节值大于 127 时，以太网客户端库返回的值为 63。

以下是我在 arduino 方面所做的基本示例。为了整洁起见，有些东西已被删除。

byte buffer[32];
memset(buffer, 0, 32);

int data;
int i=0;

data = client.read();
while(data != -1 && i < 32)
{
  buffer[i++] = (byte)data;
  data = client.read();
}

因此，每当输入字节大于 127 时，变量“data”最终将被设置为 63！起初我认为问题出在更远的地方（缓冲区过去是字符而不是字节），但是当我在读取后立即打印出“数据”时，它仍然是 63。

有什么想法可能导致此问题吗？我知道 client.read() 应该输出 int 并在内部从套接字读取数据作为 uint8_t 这是一个完整的字节且无符号，所以我应该至少能够转到 255...

编辑：你说得对，汉斯。没有意识到 Encoding.ASCII.GetBytes 仅支持前 7 位，而不支持全部 8 位。

原文

I'm using an Arduino (duemilanove) with the official Ethernet shield to send data to the controller for controlling an LED matrix. I am trying to send some raw 32-bit unsigned int values (unix timestamps) to the controller by taking the 4 bytes in the 32-bit value on the desktop and sending it to the arduino as 4 consecutive bytes. However, whenever a byte value is larger than 127, the returned value by the ethernet client library is 63.

The following is a basic example of what I'm doing on the arduino side of things. Some things have been removed for neatness.

byte buffer[32];
memset(buffer, 0, 32);

int data;
int i=0;

data = client.read();
while(data != -1 && i < 32)
{
  buffer[i++] = (byte)data;
  data = client.read();
}

So, whenever the input byte is bigger than 127 the variable "data" will end up getting set to 63! At first I thought the problem was further down the line (buffer used to be char instead of byte) but when I print out "data" right after the read, it's still 63.

Any ideas what could be causing this? I know client.read() is supposed to output int and internally reads data from the socket as uint8_t which is a full byte and unsigned, so I should be able to at least go to 255...

EDIT: Right you are, Hans. Didn't realize that Encoding.ASCII.GetBytes only supported the first 7 bits and not all 8.

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