如何使用Python从串口读取二进制数据(struct)?

时间:2014-12-28 21:08:55

标签: python struct serial-port arduino binary-data

使用Python读取串行数据(结构中的数据包)时遇到问题。

在我的Arduino中,固件正在向我发送数据(这是来自Arduino代码):

***********************************************************
For proper communication packet format given below have to be supported:
///////////////////////////////////////////////
////////// Packet Format Version 2 ////////////
///////////////////////////////////////////////
// 17-byte packets are transmitted from Olimexino328 at 256Hz,
// using 1 start bit, 8 data bits, 1 stop bit, no parity, 57600 bits per second.

// Minimial transmission speed is 256Hz * sizeof(Olimexino328_packet) * 10 = 43520 bps.

struct Olimexino328_packet
{
  uint8_t   sync0;      // = 0xa5
  uint8_t   sync1;      // = 0x5a
  uint8_t   version;    // = 2 (packet version)
  uint8_t   count;      // packet counter. Increases by 1 each packet.
  uint16_t  data[6];    // 10-bit sample (= 0 - 1023) in big endian (Motorola) format.
  uint8_t   switches;   // State of PD5 to PD2, in bits 3 to 0.
};
*/
/**********************************************************/

变量看起来像这样:

//Write packet header and footer
 TXBuf[0] = 0xa5;    //Sync 0
 TXBuf[1] = 0x5a;    //Sync 1
 TXBuf[2] = 2;       //Protocol version
 TXBuf[3] = 0;       //Packet counter
 TXBuf[4] = 0x02;    //CH1 High Byte
 TXBuf[5] = 0x00;    //CH1 Low Byte
 TXBuf[6] = 0x02;    //CH2 High Byte
 TXBuf[7] = 0x00;    //CH2 Low Byte
 TXBuf[8] = 0x02;    //CH3 High Byte
 TXBuf[9] = 0x00;    //CH3 Low Byte
 TXBuf[10] = 0x02;   //CH4 High Byte
 TXBuf[11] = 0x00;   //CH4 Low Byte
 TXBuf[12] = 0x02;   //CH5 High Byte
 TXBuf[13] = 0x00;   //CH5 Low Byte
 TXBuf[14] = 0x02;   //CH6 High Byte
 TXBuf[15] = 0x00;   //CH6 Low Byte 
 TXBuf[2 * NUMCHANNELS + HEADERLEN] =  0x01;    // Switches state

将数据放到这些变量中如下所示:

//Read the 6 ADC inputs and store current values in Packet
for(CurrentCh=0;CurrentCh<6;CurrentCh++){
  ADC_Value = analogRead(CurrentCh);
  TXBuf[((2*CurrentCh) + HEADERLEN)] = ((unsigned char)((ADC_Value & 0xFF00) >> 8));
  // Write High Byte
  TXBuf[((2*CurrentCh) + HEADERLEN + 1)] = ((unsigned char)(ADC_Value & 0x00FF));
  // Write Low Byte
}
// Send Packet
for(TXIndex=0;TXIndex<17;TXIndex++){
  Serial.write(TXBuf[TXIndex]);
}
// Increment the packet counter
TXBuf[3]++;     

我是Python的新手,我不知道如何阅读它。例如,如何将这些变量放入列表中。我写了这样的话:

#!/usr/bin/env python
import serial

ser = serial.Serial('/dev/tty.usbmodem1411', 57600)
read_byte = ser.read()

while read_byte is not None:
    read_byte = ser.read()
    print int(read_byte.encode('hex'), 16)

结果是这样的:

228
1
165
90
2
98
2
3
1
252
1
245
1
240
1
238
1
232
1
165
90
2
99

我现在有一些像Python中的结构和方法解压缩,但我不知道如何做到这一点。请帮帮我。

0 个答案:

没有答案