Error when no tag is on Explore NFC board

[framboise314]

Hello
I compiled nxppy successfully from source

I use a little loop test :

    import sys
    import nxppy
    uid = ""
    while True:
          mifare=nxppy.Mifare()
          uid=mifare.select()
          if uid is not None:
              print uid
              uid = ""
          else:
              print "No card"
              uid = ""

When I lounch the test with a NFC tag on the board I got :

pi@raspberrypi ~ $ sudo python test_de.py
8CA6450E
8CA6450E
......
8CA6450E

When removing the NFC tag, I would like to print "No Card" but the script stops and send an error as here under :

....
8CA6450E           ==> Here I remove the NFC TAG
Traceback (most recent call last):
  File "test_de.py", line 6, in <module>
    uid=mifare.select()
nxppy.SelectError: RequestA command failed: 201
pi@raspberrypi ~ $ 

When starting the script without a NFC tag I got directly

pi@raspberrypi ~ $ sudo python test_de.py
Traceback (most recent call last):
  File "test_de.py", line 6, in <module>
    uid=mifare.select()
nxppy.SelectError: RequestA command failed: 201
pi@raspberrypi ~ $

I made another try with this script read_nfc.py :

import nxppy
while True:
   mifare=nxppy.Mifare()
   if mifare is not None:
       print "Mifare is not null"
   uid=mifare.select()
   print "Read uid"
   if uid is not None:
       break

print uid

When launched with a NFC Tag it gives

pi@raspberrypi ~ $ sudo python read_nfc.py
Mifare is not null
Read uid
8CA6450E
pi@raspberrypi ~ $

But without NFC Tag on the board i have the same error...

pi@raspberrypi ~ $ sudo python read_nfc.py
Mifare is not null
Traceback (most recent call last):
  File "read_nfc.py", line 6, in <module>
    uid=mifare.select()
nxppy.SelectError: RequestA command failed: 201
pi@raspberrypi ~ $

I do not know why this append and if I make something wrong.
My goal is to write a post for the blog www.framboise314.fr. I would like to tell my readers how to use Explore NFC Board to open a door when a NFC Tag listed in a file is present.
But the script stops when no tag is near the board.

Hope you see where my mistake is
Best regards
François
www.framboise314.fr

[svvitale]

Hi Francois!

Thanks for reaching out! This is expected behavior. In the latest revision of nxppy (which uses a Mifare class instead of static methods), we throw an exception if the call to .select() fails. Here's how you would handle it (using one of your example scripts):

import nxppy
mifare=nxppy.Mifare()

while True:
    try:
        uid = mifare.select()
        print "Read uid", uid
    except nxppy.SelectError:
        pass   

I'll go and update my post on the NXP site, which I think still has the old example. Please let me know if you have any additional issues. I look forward to seeing your blog post when it's published!

Scott

[framboise314]

Thank you Scott
I try it tomorrow
the post will follow rapidly if this test is Ok
I tell you when it's on the blog
best regards
François

[framboise314]

Hello Scott
the post is online (2 parts)
http://www.framboise314.fr/jai-teste-pour-vous-la-carte-explore-nfc-delement-14-12/
http://www.framboise314.fr/jai-teste-pour-vous-la-carte-explore-nfc-delement-14-22/
thank you again
happy xmas and new year to you and familly
François

[svvitale]

Thanks Francois! I've just tweeted your post. Excited to see it! Joyeux
noël à vous et à votre famille aussi!

On Sun Dec 21 2014 at 10:08:26 AM Francois MOCQ notifications@github.com
wrote:

Hello Scott
the post is online (2 parts)

http://www.framboise314.fr/jai-teste-pour-vous-la-carte-explore-nfc-delement-14-12/

http://www.framboise314.fr/jai-teste-pour-vous-la-carte-explore-nfc-delement-14-22/
thank you again
happy xmas and new year to you and familly
François

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