Python 从树莓派发送串行通信
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Sending serial communication from Raspberry pi
提问by Daanii
I am sending serial data from a Raspberry Pi to an Arduino using a Python program. I am running Python 2.7.3. The program is:
我正在使用 Python 程序将串行数据从 Raspberry Pi 发送到 Arduino。我正在运行 Python 2.7.3。该计划是：
import serial
ser = serial.Serial('/dev/ttyACM0', 115200)
ser.write(b'\x4c\xff\x46')
The problem is that nothing seems to be sent by these three lines if they are run in a program. But if I run them line by line in a Python shell, they work fine.
问题是，如果这三行在程序中运行，它们似乎没有发送任何内容。但是如果我在 Python shell 中逐行运行它们，它们就可以正常工作。
Also, if I have the Arduino Serial Monitor open, the program works fine as well, without running the lines one by one in the shell.
此外，如果我打开了 Arduino 串行监视器，该程序也能正常运行，无需在 shell 中逐行运行。
EDITED TO ADD:
编辑添加：
It seems that there is some delay in sending to the Arduino. So when I run the code in interpretive mode, it works, but if as a program, it doesn't. I think that because I tried the same program on a Windows machine.
发送到 Arduino 似乎有一些延迟。所以当我在解释模式下运行代码时，它可以工作，但如果作为程序，它就不行。我认为这是因为我在 Windows 机器上尝试了相同的程序。
import serial
ser = serial.Serial('COM8', 115200)
ser.write(b'\x4c\x20\x46')
If I run the program in interpretive mode, or even in debugging mode with a breakpoint on the ser.write command, it works. But not if run as a program.
如果我在解释模式下运行程序，或者甚至在调试模式下在 ser.write 命令上设置断点，它都可以工作。但如果作为程序运行则不然。
EDITED TO ADD MORE:
编辑添加更多：
It turns out that the Arduino has an auto-reset on serial communications that has to be disabled:
事实证明，Arduino 对必须禁用的串行通信具有自动重置功能：
http://playground.arduino.cc/Main/DisablingAutoResetOnSerialConnection#.UwP_wfldV8E
http://playground.arduino.cc/Main/DisablingAutoResetOnSerialConnection#.UwP_wfldV8E
http://forum.arduino.cc/index.php/topic,28723.0.html
http://forum.arduino.cc/index.php/topic,28723.0.html
I used a 220 uF capacitor between the RESET pin and ground. That works.
我在 RESET 引脚和地之间使用了一个 220 uF 的电容器。那个有效。
Tough to be bitten by a bug like that! It still smarts.
被这样的虫子咬了好难受！它仍然很聪明。
回答by Cugomastik
Try this. If you can't run it under idle or etc, try terminal by typing python name.py. I also suggest you to check the data coming or written from/to Rpi with putty to be sure.
尝试这个。如果您无法在空闲等情况下运行它，请通过键入 python name.py 来尝试终端。我还建议您使用腻子检查来自/写入 Rpi 的数据以确保。
import serial
import time
def readlineCR(port):
rv = ""
while True:
ch = port.read()
rv += ch
if ch == '\r' or ch == '':
return rv
port = serial.Serial("/dev/ttyAMA0", baudrate = 7200, timeout = 2)
while True:
rcv = readlineCR(port)
port.write("I typed: " + repr(rcv))
print(rcv)
