我正在尝试在一些python代码和arduino代码之间来回“乒乓”信息。我想定期向arduino代码发送两个设定值(例如在分钟内),在arduino上读取它们并更新变量,然后定期(例如在30秒内)将状态信息从arduino发送回python。最终,python将从mySQL db发送信息并从中提取信息(后来的dev)。
目前,我无法获得可靠往返的信息。我没有在搜索中找到与此相近的任何内容,而且我尝试修改的所有内容均无效。我最近的是这个(它实际上并没有在发送和接收之间来回切换):
Python
#!/usr/bin/python
import serial
import syslog
import time
#The following line is for serial over GPIO
port = '/dev/ttyS0'
ard = serial.Serial(port,9600,timeout=5)
i = 0
while (i < 4):
# Serial write section
setTempCar1 = 63
setTempCar2 = 37
ard.flush()
setTemp1 = str(setTempCar1)
setTemp2 = str(setTempCar2)
print ("Python value sent: ")
print (setTemp1)
ard.write(setTemp1)
time.sleep(4)
# Serial read section
msg = ard.readline()
print ("Message from arduino: ")
print (msg)
i = i + 1
else:
print "Exiting"
exit()
的Arduino:
// Serial test script
int setPoint = 55;
String readString;
void setup()
{
Serial.begin(9600); // initialize serial communications at 9600 bps
}
void loop()
{
while(!Serial.available()) {}
// serial read section
while (Serial.available())
{
if (Serial.available() >0)
{
char c = Serial.read(); //gets one byte from serial buffer
readString += c; //makes the string readString
}
}
if (readString.length() >0)
{
Serial.print("Arduino received: ");
Serial.println(readString); //see what was received
}
delay(500);
// serial write section
char ard_sends = '1';
Serial.print("Arduino sends: ");
Serial.println(ard_sends);
Serial.print("\n");
Serial.flush();
}
我最终得到的是重复的相同值(不是实际发送的值,不确定是字符串还是字节的问题),什么也没有返回到python脚本。任何帮助或想法,我们将不胜感激。谢谢。
编辑:修改的代码为我当前正在运行,如下所示。Arduino正在接受minicom验证的精细和串行通信。但是python脚本在“来自arduino的消息:”之后仍然打印空白行。
在写和读之间,您不应该关闭Python中的串行端口。当Arduino响应时,端口仍有可能关闭,在这种情况下,数据将丢失。
while running:
# Serial write section
setTempCar1 = 63
setTempCar2 = 37
setTemp1 = str(setTempCar1)
setTemp2 = str(setTempCar2)
print ("Python value sent: ")
print (setTemp1)
ard.write(setTemp1)
time.sleep(6) # with the port open, the response will be buffered
# so wait a bit longer for response here
# Serial read section
msg = ard.read(ard.inWaiting()) # read everything in the input buffer
print ("Message from arduino: ")
print (msg)
PythonSerial.read
函数默认情况下仅返回一个字节,因此您需要在循环中调用它或等待数据传输然后读取整个缓冲区。
在Arduino方面,loop
当没有可用数据时,您应该考虑函数中会发生什么。
void loop()
{
// serial read section
while (Serial.available()) // this will be skipped if no data present, leading to
// the code sitting in the delay function below
{
delay(30); //delay to allow buffer to fill
if (Serial.available() >0)
{
char c = Serial.read(); //gets one byte from serial buffer
readString += c; //makes the string readString
}
}
相反,请等待loop
函数的开始直到数据到达:
void loop()
{
while (!Serial.available()) {} // wait for data to arrive
// serial read section
while (Serial.available())
{
// continue as before
编辑2
这是从Python与您的Arduino应用进行交互时得到的结果:
>>> import serial
>>> s = serial.Serial('/dev/tty.usbmodem1411', 9600, timeout=5)
>>> s.write('2')
1
>>> s.readline()
'Arduino received: 2\r\n'
因此,这似乎很好。
在测试Python脚本时,似乎问题在于打开串行端口时Arduino会重置(至少我的Uno会这样做),因此需要等待几秒钟才能启动。您还只读取了一行响应,因此我还在下面的代码中修复了该问题:
#!/usr/bin/python
import serial
import syslog
import time
#The following line is for serial over GPIO
port = '/dev/tty.usbmodem1411' # note I'm using Mac OS-X
ard = serial.Serial(port,9600,timeout=5)
time.sleep(2) # wait for Arduino
i = 0
while (i < 4):
# Serial write section
setTempCar1 = 63
setTempCar2 = 37
ard.flush()
setTemp1 = str(setTempCar1)
setTemp2 = str(setTempCar2)
print ("Python value sent: ")
print (setTemp1)
ard.write(setTemp1)
time.sleep(1) # I shortened this to match the new value in your Arduino code
# Serial read section
msg = ard.read(ard.inWaiting()) # read all characters in buffer
print ("Message from arduino: ")
print (msg)
i = i + 1
else:
print "Exiting"
exit()
现在是上面的输出:
$ python ardser.py
Python value sent:
63
Message from arduino:
Arduino received: 63
Arduino sends: 1
Python value sent:
63
Message from arduino:
Arduino received: 63
Arduino sends: 1
Python value sent:
63
Message from arduino:
Arduino received: 63
Arduino sends: 1
Python value sent:
63
Message from arduino:
Arduino received: 63
Arduino sends: 1
Exiting
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