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 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

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

$ python

>>> import piface.pfio as p

>>> p.init()

>>> p.digital_read(0)

Hi Jeff

Yes I did click on the override enable and then all on/off and individual pins but nothing......

Thanks anyway

Keith

Hi Jeff

Yes I did click on the override enable and then all on/off and individual pins but nothing......

Thanks anyway

Keith