PiFace connection

The PiFace uses the SPI interface, so make sure that is enabled in the Raspi-config.  Also, make sure your chip_select jumpers. (JP1,JP2) are set correctly.  It seems odd that it is looking for chip_select=1 if you are only using a single PiFace board (usually defaults to 0).

Have you tried the emulator to verify the software is installed correctly?

Hi thanks for reply Ralph, I've checked and enabled the SPI interface in Raspi-Config. Is there any way to edit the value back to zero? 

I'm not sure why the default in core.py is for chip_select=1, but you can either edit this line in the file or you can change your jumpers.  If you change the jumpers then you will have to explicitly set the address when doing reads and writes.  I would edit the file unless you have multiple PiFaces.

At the top of core.py:

     import pifacecommon.mcp23s17

     import pifacecommon.interrupts

     import pifacecad.lcd

     DEFAULT_SPI_BUS = 0

    DEFAULT_SPI_CHIP_SELECT = 1

     NUM_SWITCHES = 8

From your traceback, the file is /usr/lib/python3/dist-packages/pifacecad/core.py

I don't think the Control and Display has selectable jumpers on it.  At least the one I have does not have selectable jumpers on it.

@cclegends I am not sure it is a good idea to mess with the underlying code and really should not be necessary.   You have installed the Python 3 version of the PiFace code correct?

Run the following on your Pi to ensure your SPI interface is up and running

ls /dev/*spi*
/dev/spidev0.0  /dev/spidev0.1

You should see the 2 SPI devices to show.

Could you post the code you are using?

I suspect you have gone through the How-To-Guides from the following link, right?

http://www.piface.org.uk/products/piface_control_and_display/

Hi John,  Yes, i did follow the How-to_Guide to establish the connections. I've also ran the ls /dev/*spi*. Both interface is confirm up and running. But for Python3 version of PiFace code i think i've installed it correctly. Is there anywhere to confirm that? Thanks

Try running through what is listed at the following.  This should verify the config.

http://piface.github.io/pifacecad/installation.html#sysinfo-service

Have a look-see at the troubleshooting suggestion posted at the following

https://github.com/piface/pifacecad/issues/24

I vaguely remember having to do this.

This is what I have in the spi.py file

/usr/lib/python3/dist-packages/pifacecommon/spi.py

    
# create the spi transfer struct
    
transfer = spi_ioc_transfer(
        
tx_buf=ctypes.addressof(wbuffer),
        
rx_buf=ctypes.addressof(rbuffer),
        
len=ctypes.sizeof(wbuffer),
        
speed_hz=ctypes.c_uint32(100000)
    
)

Hi Jon,

Thanks, hope I didn’t led Christopher astray.  I was thinking about the PiFace Digital 2.  I should pay more attention.

He  should follow your advice.

Sorry Christopher...

Ralph

It's alright Ralph.  Trying the method that Jon posted.

Updates, Thanks Jon for the code modification. Now the display power ups and working but there is a little hiccup. Where it can't display free memory on the display. The tracebacks are :

Traceback (most recent call last):

  File "sysinfo.py", line 75, in <module>

    show_sysinfo()

  File "sysinfo.py", line 56, in show_sysinfo

    cad.lcd.write(":{}".format(get_my_free_mem()))

  File "sysinfo.py", line 35, in get_my_free_mem

    used_mem = float(run_cmd(USED_MEM_CMD))

ValueError: could not convert string to float: