PiFace Problems

Keith, you are not alone. The 'documentation' with the piface is worse than useless. I particularly like the typo on page 2 of the 'instructions' (etc/ which should be /etc/) and that if the emulator fails (I can't get it to work – ends with 'segmentation fault') the 'instructions' that follow are, again, useless. I will get it working in the end, but no thanks to the fools at man.ac.uk. How difficult would it have been to provide basic instructions in the box? Good luck with it - I'll reply back when I've finished arm-wrestling with it and got it doing something (I have a job in mind).

... not sure if urls are allowed here - if they are, here's some documentation for piface ...

https://docs.google.com/folder/d/0B-UAZ9CyJCLGQjJ3RDlqa2pqaDg/edit?pli=1

Hi Keith,

Does the board work when just using Python? Try opening a Python shell and talking to PiFace:

    $ python
    >>> import piface.pfio as p
    >>> p.init()
    >>> p.digital_write(1, 1)

What error does that produce?

Maybe a little late, but I fixed the spi permission issue by adding myself to the spiuser group.

Hi Thomas

I tried your code in a Python shell from a LXTerminal and from Python 2.7.3 Shell.

No errors were reported when I typed in each of the lines but I guess this was going to switch on an LED or relay? Neither happened.

Thanks for your help so far.

Keith

Hi Keith, did you ever get you PiFace to work?

I spent two days struggling with this.  I found it hard to find documentation and I could have saved myself two days of trouble-shooting had I just had access to a schematic.

My PiFace was shipped without a jumper on JP7.  The absence of JP7 disables the 5 V rail for the outputs so there was no lights, no relay click.  Adding JP7 made the PiFace work as advertised.

While I'm typing I may as well add that I'm disappointed that the designer of the PiFace didn't make the unused IO ports on the Raspberry Pi available on the board.  This limits what would have otherwise been a very nice addition to the Pi.

Dave

Hi Dave

No my PiFace is still not working and both of them have a jumper 7 installed.

Thanks anyway

Keith

Did you get any error messages in the terminal window when you ran the emulator?

Hi Jeff

No errors, the emulator window opens and says piface detected but nothing works. In the terminal window the cursor waits and returns to root@raspberrypi:~# once the emulator has been closed.

Cheers

Keith

PiFace detected...that's a start. Did you click the override button?

Keith, can you run the commands I listed in post #8 and tell me the output? If you can see the SPI device files (/dev/spidev0.0 and /dev/spidev0.1) and running the Python shell commands doesn't error then it's probably an error with your board.

Also, try reading from the board:

$ python

>>> import piface.pfio as p

>>> p.digital_read(0)

This should return a 1 or 0 value depending on whether the switch was pressed. So you should run the digital_read() command twice, once while holding the first switch and once while not. The returned values should be different. If they are the same even when you have held down the switch then it's a hardware fault.

Hello Thomas

The commands returned the following:

root@raspberrypi:~# ls -l /dev/spidev*

crw-rw---T 1 root spiuser 153, 0 Jan  1  1970 /dev/spidev0.0

crw-rw---T 1 root spiuser 153, 1 Jan  1  1970 /dev/spidev0.1

However, the input was more revealing:

root@raspberrypi:~# python

Python 2.7.3 (default, Jan 13 2013, 11:20:46)

[GCC 4.6.3] on linux2

Type "help", "copyright", "credits" or "license" for more information.

>>> import piface.pfio as p

>>> p.digital_read(0)

Traceback (most recent call last):

  File "<stdin>", line 1, in <module>

  File "/usr/local/lib/python2.7/dist-packages/piface/pfio.py", line 249, in digital_read

    current_pin_values = read_input()

  File "/usr/local/lib/python2.7/dist-packages/piface/pfio.py", line 300, in read_input

    port, data = read(INPUT_PORT)

  File "/usr/local/lib/python2.7/dist-packages/piface/pfio.py", line 329, in read

    operation, port, data = send([(READ_CMD, port, 0xff)])[0] # send is expecting and returns a list

  File "/usr/local/lib/python2.7/dist-packages/piface/pfio.py", line 342, in send

    raise InitError("The pfio module has not yet been initialised. Before send(), call init().")

piface.pfio.InitError: The pfio module has not yet been initialised. Before send(), call init().

>>>

Thanks

Keith

Hello Thomas

The commands returned the following:

root@raspberrypi:~# ls -l /dev/spidev*

crw-rw---T 1 root spiuser 153, 0 Jan  1  1970 /dev/spidev0.0

crw-rw---T 1 root spiuser 153, 1 Jan  1  1970 /dev/spidev0.1

However, the input was more revealing:

root@raspberrypi:~# python

Python 2.7.3 (default, Jan 13 2013, 11:20:46)

[GCC 4.6.3] on linux2

Type "help", "copyright", "credits" or "license" for more information.

>>> import piface.pfio as p

>>> p.digital_read(0)

Traceback (most recent call last):

  File "<stdin>", line 1, in <module>

  File "/usr/local/lib/python2.7/dist-packages/piface/pfio.py", line 249, in digital_read

    current_pin_values = read_input()

  File "/usr/local/lib/python2.7/dist-packages/piface/pfio.py", line 300, in read_input

    port, data = read(INPUT_PORT)

  File "/usr/local/lib/python2.7/dist-packages/piface/pfio.py", line 329, in read

    operation, port, data = send([(READ_CMD, port, 0xff)])[0] # send is expecting and returns a list

  File "/usr/local/lib/python2.7/dist-packages/piface/pfio.py", line 342, in send

    raise InitError("The pfio module has not yet been initialised. Before send(), call init().")

piface.pfio.InitError: The pfio module has not yet been initialised. Before send(), call init().

>>>

Thanks

Keith

Ah, my bad. You need to initialised the pfio first.

$ python

>>> import piface.pfio as p

>>> p.init()

>>> p.digital_read(0)

Hi Thomas

I tried the code below:

root@raspberrypi:/home/pi# python

Python 2.7.3 (default, Jan 13 2013, 11:20:46)

[GCC 4.6.3] on linux2

Type "help", "copyright", "credits" or "license" for more information.

>>> import piface.pfio as p

>>> p.init()

>>> p.digital_read(0)

1

>>> p.digital_read(1)

1

>>> p.digital_read(0)

1

>>> p.digital_read(1)

1

>>>

For the first two tries, no button was pressed. For the second two, I pressed all the buttons.

Cheers

Keith

Hi Thomas

Just tried the same again with my other Piface board, exactly the same results.

Cheers

Keith

Where are your jumpers on the board in the correct place? They should both be on 0. Here is a picture I just took of my PiFace for reference.

Hi Thomas

THAT FIXED IT!

Both PiFace came with the jumpers set in the other position - THANK YOU! (and why would they do that?)

I believe that Scratch needs an updated version to work with PiFace, is there anywhere I can download it from using my current version of Raspian?

Thanks

Keith

Ah-ha! That's brilliant news! The jumper switches tell PiFace what number it is. With both set to 0, you tell PiFace that it's board 0. By default the Python module addresses board 0 so that's why it wasn't working when you had it set to whatever-else.

I don't think you need an updated version of Scratch, you just need to enable Mesh. Here are some old instructions (I'll be honest, they need improving ). If you have any trouble then start a new thread and I'll try to help when I can.

Good luck, and have fun!

Hi Thomas,

I just installed the new Python3 version of pifacedigitalio following the directions on github: https://github.com/piface/pifacedigitalio. I'm using the latest version of Raspbian (2013-02-09) with all of the latest updates installed (via apt) and the latest firmware (via hexxeh's rpi-update script).

For some reason, my system is not setting up the permissions properly for the /dev/spidev* files. Output of 'ls -al /dev/spi*' is below:

pi@raspberrypi ~ $ sudo ls -al /dev/spi*

crw------- 1 root root 153, 0 Dec 31  1969 /dev/spidev0.0

crw------- 1 root root 153, 1 Dec 31  1969 /dev/spidev0.1

I'm getting ready to just add manual udev rules to set the permissions, but I wanted to check as to why they aren't being setup automatically. Does the new Python3 version of the Piface Python IO library setup not handle permission setup yet?

Thanks,

Andy

Ah, so I haven't! I'll add this to the install script tomorrow, it must have slipped my mind since I was already working on a machine that had the permisions set up.

For now, try running the spidev-setup script here.

Thanks for the heads-up!

Yea, I just manully ran the old script and got it working. Thanks of the confirmation. With that sorted out, both the io library and emulater seem to be working properly.

-Andy

I've updated the pifacedigitalio install script to update the spi permissions. Everything should work now, I might also add auto un-blacklisting the spi kernel module later.