在写和读之间，您不应该关闭Python中的串行端口。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，您应该考虑loop没有可用数据时函数中会发生什么。
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
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。
在测试您的Python脚本时，似乎问题在于打开串口时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，因此我也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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