通过PySerial向Arduino发送整数值

Question

我需要发送大于255的整数，有人知道怎么做吗？

Answer 1

简单多了：

  crc_out = binascii.crc32(data_out) & 0xffffffff   # create unsigned long
  print "crc bytes written",arduino.write(struct.pack('<L', crc_out)) #L, I whatever u like to use just use 4 bytes value

  unsigned long crc_python = 0;
  for(uint8_t i=0;i<4;i++){        
    crc_python |= ((long) Serial.read() << (i*8));
  }

不需要联合，代码也短！

Answer 2

用Python的struct模块把它们编码成二进制字符串。我不太确定Arduino需要的是小端格式还是大端格式，不过如果它的文档没有说明清楚，做个小实验就能轻松搞明白了;-).

Answer 3

这是方法（感谢Alex的点子！）：

Python：

def packIntegerAsULong(value):
    """Packs a python 4 byte unsigned integer to an arduino unsigned long"""
    return struct.pack('I', value)    #should check bounds

# To see what it looks like on python side
val = 15000
print binascii.hexlify(port.packIntegerAsULong(val))

# send and receive via pyserial
ser = serial.Serial(serialport, bps, timeout=1)
ser.write(packIntegerAsULong(val))
line = ser.readLine()
print line

Arduino：

unsigned long readULongFromBytes() {
  union u_tag {
    byte b[4];
    unsigned long ulval;
  } u;
  u.b[0] = Serial.read();
  u.b[1] = Serial.read();
  u.b[2] = Serial.read();
  u.b[3] = Serial.read();
  return u.ulval;
}
unsigned long val = readULongFromBytes();
Serial.print(val, DEC); // send to python to check

通过PySerial向Arduino发送整数值

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