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PiFace: Controlling outputs via bash script or file in /sys or /proc or even in a ram-disk

e14 Contributor

hi,

 

i have just received the piface and played with python a little. i am more versed in bash scripting so i am looking for a way to control the piface via bash script. alternatively i am looking for a way to be able to use python but without the need to initialise the board before every access. i like to keep lets say output 1 high while setting output 5 high instead of having all reset and then write write both outputs. ideally i would find one file per input and one per output which i can just cat to read input 0/1 and echo 1/0 to set output high or low. can that be done in python ? any suggestions ?

 

Thanks

Jan

  • hi again,

     

    since i have no clue about python i have googled some stuff and came up with this simple script. it basically looks for 1 or 0 in the files out0 - out7. if it finds 1 the output is set to high, if 0 its set to low. i am sure there is a more elegant way doing this but this seems to work for me.

     

    #!/usr/bin/python

    import time

    import piface.pfio as pfio

    pfio.init()

    count = 0

    while (count < 1):

            if '1' in open('/ramdisk/out0').read():

                    pfio.digital_write(0,1)

            else:

                    pfio.digital_write(0,0)

            if '1' in open('/ramdisk/out1').read():

                    pfio.digital_write(1,1)

            else:

                    pfio.digital_write(1,0)

            if '1' in open('/ramdisk/out2').read():

                    pfio.digital_write(2,1)

            else:

                    pfio.digital_write(2,0)

            if '1' in open('/ramdisk/out3').read():

                    pfio.digital_write(3,1)

            else:

                    pfio.digital_write(3,0)

            if '1' in open('/ramdisk/out4').read():

                    pfio.digital_write(4,1)

            else:

                    pfio.digital_write(4,0)

            if '1' in open('/ramdisk/out5').read():

                    pfio.digital_write(5,1)

            else:

                    pfio.digital_write(5,0)

            if '1' in open('/ramdisk/out6').read():

                    pfio.digital_write(6,1)

            else:

                    pfio.digital_write(6,0)

            if '1' in open('/ramdisk/out7').read():

                    pfio.digital_write(7,1)

            else:

                    pfio.digital_write(7,0)

            time.sleep( 1 )

    count = count + 0

  • in reply to e14 Contributor

    Jan

    Have you read Gough Lui's review of the PiFace ?

    http://www.element14.com/community/roadTestReviews/1468

     

    He used C to control the relays, and maybe this gives you what you need.

     

     

    mark