Question

我是Python的新手，我试图在rasberry pi上构建一个Rfid读卡器。我使用python脚本读取卡片并获取卡片UID，然后处理其他功能等，但是在传递变量时我碰到了墙，

我的代码：

    import RPi.GPIO as GPIO
    import MFRC522
    import signal
    import time
    import datetime
    import socket
    import run

    device = (socket.gethostname()) # Define Device name
    # Define logfile Long version |
    logfile = "/home/piadmin/MFRC522-python/" + device + ".csv"
    # logfile = device + ".csv"
    continue_reading = True

    # Capture SIGINT for cleanup when the script is aborted
    def end_read(signal,frame):
            global continue_reading
            print "Ctrl+C captured, ending read."
            continue_reading = False
            GPIO.cleanup()

    # Hook the SIGINT
    signal.signal(signal.SIGINT, end_read)

    # Create an object of the class MFRC522
    MIFAREReader = MFRC522.MFRC522()

    # Welcome message
    print "Waiting for card to read.."
    print "Press Ctrl-C to stop."

    # This loop keeps checking for chips. If one is near it will get the UID and authenticate
    while continue_reading:
            # Scan for cards
            status, TagType = MIFAREReader.MFRC522_Request(MIFAREReader.PICC_REQIDL)
            # If a card is found
            if status == MIFAREReader.MI_OK:
                    print "Card detected"
                    # Get the UID of the card
                    status,uid = MIFAREReader.MFRC522_Anticoll()
                    print uid
                    time.sleep (1)
                    run.run()

在最后一行上面的代码中调用run.py WIP：

    idlist = file('/home/piadmin/temp/idlist.txt') # known ID list
    inlog = file('/home/piadmin/temp/in.txt') # IN log
    status = 'None'

    def checkid():
            for line in idlist:
                    if uid in line:
                            return True
            else:
                    return False
    def checkin():
            for line in inlog:
                    if uid in line:
                            return True
            else:
                    return False

    #uid = raw_input("Please enter uid: ")
    #print "uid ->", uid

    def run():
            if checkid() == True:
                    print 'id = true'
                    if checkin() == True:
                            print 'in = true'
                            print 'set OUT'
                            status = 'OUT'
                            f = open('in.txt','r+')
                            d = f.read().splitlines()
                            f.seek(0)
                            for i in d:
                                    if i != uid:
                                            f.write(i)
                                            f.write('\n')
                            f.truncate()
                            f.close()
                            return True
                    else:
                            print 'in = false, set IN'
                            status = 'IN'
                            f = open('in.txt','a')
                            f.write(str(uid))
                            f.write('\n')
                            f.flush()
                            f.close()
                            return True
            else:
                    print 'check id not true, not checking more (finger)'
                    return False

一旦执行代码，我得到输出：

    Waiting for card to read..
    Press Ctrl-C to stop.
    Card detected
    [101, 116, 172, 79, 242]
    Traceback (most recent call last):
      File "read.py", line 49, in <module>
        run.run()
      File "/home/piadmin/work/run.py", line 26, in run
        if checkid() == True:
      File "/home/piadmin/work/run.py", line 11, in checkid
        if uid in line:
    NameError: global name 'uid' is not defined

我无法弄明白为什么＆＃34; NameError：全球名称＆＃39; uid＆＃39;没有定义＆＃34;发生以及如何正确传递在每个循环传递上分配的uid值。

Answer 1

您在哪里定义变量uid？如果全局变量＆＃34; uid＆＃34;在模块中定义，您可以使用以下命令从其他模块访问：

theNameOfModuleWhichDefineUID.uid

修改

例如，如果全局变量＆＃34; uid＆＃34;在模块＆＃34; iammodule＆＃34;中定义您可以使用此命令访问：

import iammodule print(iammodule.uid)

或

from iammodule import * print(uid)

Python将变量传递给调用脚本|全球名称＆＃39; uid＆＃39;没有定义

1 个答案: