Question

我是python的新手，我正在尝试使用LibMPSSE库从霍尼韦尔差压传感器读取压力数据。我是从Adafruit FT232H芯片上读到的，我在ubuntu Linux上使用的是python 2.7.6。

#!/usr/bin/env python


from mpsse import *

SIZE = 2    # 2 bytes MSB first
WCMD = "\x50"   # Write start address command
RCMD = "\x51"       # Read command
FOUT = "eeprom.txt" # Output file

try:
    eeprom = MPSSE(I2C)

    # print "%s initialized at %dHz (I2C)" % (eeprom.GetDescription(), eeprom.GetClock())

    eeprom.Start()
    eeprom.Write(WCMD)
    # Send Start condition to i2c-slave (Pressure Sensor)
    if eeprom.GetAck() == ACK:
        # ACK received,resend START condition and set R/W bit to 1 for read 
        eeprom.Start()
        eeprom.Write(RCMD)

        if eeprom.GetAck() == ACK:
            # ACK recieved, continue supply the clock to slave
            data = eeprom.Read(SIZE)
            eeprom.SendNacks()
            eeprom.Read(1)
        else:
            raise Exception("Received read command NACK2!")
    else:
        raise Exception("Received write command NACK1!")

    eeprom.Stop()
    print(data)
    eeprom.Close()

except Exception, e:
    print "MPSSE failure:", e

根据库，Read返回一个大小字节的字符串，每当我想打印数据时，我看到的唯一输出是 2 T_`ʋ Q} * / eE 。我尝试用utf-8进行编码但仍然没有运气。

Answer 1

当字符串中的字节/字符（在您的情况下为data）包含不可打印的字符时，Python可能会打印“怪异”输出。要“查看”各个字节的内容（如整数或十六进制），请执行以下操作：

print(','.join(['{:d}'.format(x) for x in map(ord, data)])) # decimal

或

print(','.join(['{:02X}'.format(x) for x in map(ord, data)]))

由于data缓冲区的长度由SIZE=2设置，要从整个缓冲区中提取每个字节作为整数，您可以执行以下操作：

hi, lo = map(ord, data)
# or:
hi = ord(data[0])
lo = ord(data[1])

要详细了解ord及其作用，请参阅https://docs.python.org/2/library/functions.html#ord

打印时奇怪的Python输出

1 个答案: