Simatic LED demo #001
Posted by Anonymous on Mon 9th Aug 2021 12:37
raw | new post

#!/usr/bin/ksh93

#
# Simatic LED demo #001
#
# Binary counter from hell - counts fron 0 to pow(2,number_of_leds),
# and turns the LEDs on/off based on the binary value
#


compound c # ksh93 compound variable (sort of |struct|)
compound -a c.ar
integer c.num_leds
typeset f # filename
integer i
typeset -i2 bin_counter # binary counter 0000...0001...0010...


#
# Enumerate all available LEDs
# (the simatic-ipc-leds.ko driver will register it's LEDs
# via the Linux LED driver, see
# https://www.kernel.org/doc/html/latest/leds/leds-class.html how to
# use it)
#
(( i=0 ))
for f in $(find '/sys/devices/platform/simatic_ipc_leds/leds/' -name 'brightness') ; do
        c.ar[i].filename="$f"
        (( c.ar[i].index=i ))
        # open file FD for later usage, this is more efficient than
        # doing an |open(),write(),close()|-cycle for each time
        # we flash an LED
        redirect {c.ar[i].fd}<> "$f"

        (( i++ ))
done

# count LEDs
(( c.num_leds=${#c.ar[@]} ))


#
# print configuration
#
print -v c

# Bail out if there is no hardware
if (( c.num_leds == 0 )) ; then
        print -u2 -f $"%s: No leds available.\n" "$0"
        exit 1
fi


#
# main
#
typeset -R${c.num_leds} s # string with field width c.num_leds


while true ; do
        for (( bin_counter=0 ; bin_counter < pow(2,c.num_leds) ; bin_counter++ )) ; do
                # strip the '2#' prefix
                s="${bin_counter:2:c.num_leds}"

                printf $"Value: |%s|\n" "$s"

                for i in "${!c.ar[@]}" ; do
                        print -u ${c.ar[i].fd} $(( ${s:$((c.ar[i].index)):1} ))
                done
                sleep 0.2
        done
done
# EOF.