Arduino 的 Pyserial 问题 - 适用于 Python shell，但不适用于程序 [英] Pyserial problem with Arduino - works with the Python shell but not in a program

问题描述

好的，所以我确信我的 Arduino 电路是正确的，并且它的代码是正确的.我知道这一点是因为当我使用 Arduino IDE 中内置的串行监视器并发送H"时，LED 亮起，当我发送L"时，LED 熄灭.

All right, so I am positive my Arduino circuit is correct and the code for it. I know this because when I use the serial monitor built into the Arduino IDE and send 'H' an LED lights up, when I send 'L' that LED turns off.

现在我做了一个Python程序

Now I made a Python program

import serial
ser = serial.Serial("COM4",9600)
ser.write("H")

当我运行代码时，LED 闪烁一秒钟然后熄灭.然而，当我在 shell 中分别执行这些行时，它的工作方式就像它应该的那样.

When I run the code the LED blinks on for a second then goes back off. However when I do each of these lines separately in the shell it works just like it is supposed to.

有什么想法吗?

推荐答案

当您打开串行端口时，这会导致 Arduino 重置.由于 Arduino 需要一些时间来启动，所有输入都进入 bitbucket(或者可能进入引导加载程序，上帝知道用它做什么).如果您插入睡眠，则等待 Arduino 出现您的串行代码.这就是它交互工作的原因；您正在等待软件启动所需的 1.5 秒.

When you open the serial port, this causes the Arduino to reset. Since the Arduino takes some time to bootup, all the input goes to the bitbucket (or probably to the bootloader which does god knows what with it). If you insert a sleep, you wait for the Arduino to come up so your serial code. This is why it works interactively; you were waiting the 1.5 seconds needed for the software to come up.

我确认打开串口会重置我的Arduino Uno；我刷了一个程序，该程序将使 setup() 例程中的 LED 闪烁——调用 open("/dev/ttyACM0") 足以触发重置.恕我直言，这是串行支持中令人困惑且未记录的皱纹.

I confirmed that opening the serial port resets my Arduino Uno; I flashed a program which will blink the LED from the setup() routine -- calling open("/dev/ttyACM0") was sufficient to trigger the reset. This is IMHO a confusing and undocumented wrinkle in the serial support.

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