Shell script to make it easy to control an Adafruit USB+Serial backpack (http://www.adafruit.com/products/784) from other shell scripts

lcd.sh

#!/bin/bash

dev=/dev/serial/by-id/usb-239a_Adafruit_Industries-if00
# prefix byte for all commands
pfx='\xfe'
# named commands, associative array, start as just the hex chars
declare -A cmd=(
	[on]=42\\xff # macro for below
	[on2]=42 # +1 # arg ignored
	[off]=46
	[brightness]=99 # +1
	# [savebrightness]=98 # +1 # same as brightness
	[contrast]=50 # +1
	# [savecontrast]=91 # +1 # same as contrast
	[autoscroll]=51
	[noautoscroll]=52
	[clear]=58
	# splash=40+32
	[movecursor]=47 # +2
	[gohome]=48
	[cursorback]=4c
	[cursorforward]=4d
	[underlineon]=4a
	[underlineoff]=4b
	[blockon]=53
	[blockoff]=54
	[color]=d0 # +3
	# color macros
	# led primaries
	[white]=d0\\xff\\xff\\xff
	[red]=d0\\xff\\x00\\x00
	[green]=d0\\x00\\xff\\x00
	[blue]=d0\\x00\\x00\\xff
	# cmy(k) "primaries", roughly color balanced due to led brightness differences
	[yellow]=d0\\xff\\x80\\x00
	[cyan]=d0\\x00\\xc0\\xff
	[magenta]=d0\\xff\\x00\\x80
	# other saturated simple combos
	# full saturation red+green is just a different shade of yellow, slightly greenish
	[teal]=d0\\x00\\xff\\xff
	[purple]=d0\\xff\\x00\\xff
	# hack
	[black]=d0\\x00\\x00\\x00
	# size=d1+2
	[customchar]=4e
	# savecustom=c1+1+1+8
	# loadcustom=c0+1
	# gpiooff=56+1
	# gpioon=57+1
	# gpiostart=c3+1
	# autolinewrapon=43 # not supp because "not useful"
	# autolinewrapoff=44 # not supp because "not useful"
	
)
declare -A cmdargs=(
	[on2]=1
	[brightness]=1
	[contrast]=1
	[movecursor]=2
	[color]=3
	[customchar]=9 # 1 spot + 8 data bytes (bitmask for each row)
)
for c in "${!cmd[@]}" ; do
	# all these commands are prefixed
	cmd["$c"]="${pfx}\\x${cmd[$c]}"
done

# non-prefixed commands
cmd[nl]='\n'

# "fonts" for slots 1-8
# processed as decimal format from https://www.quinapalus.com/hd44780udg.html

declare -a font_hfill=(
	"16,16,16,16,16,16,16,16"
	"24,24,24,24,24,24,24,24"
	"28,28,28,28,28,28,28,28"
	"30,30,30,30,30,30,30,30"
	"31,31,31,31,31,31,31,31"
)

declare -a font_vfill=(
	"00,00,00,00,00,00,00,31"
	"00,00,00,00,00,00,31,31"
	"00,00,00,00,00,31,31,31"
	"00,00,00,00,31,31,31,31"
	"00,00,00,31,31,31,31,31"
	"00,00,31,31,31,31,31,31"
	"00,31,31,31,31,31,31,31"
	"31,31,31,31,31,31,31,31"
)

declare -a font_loadbars=(
	# 5 entries
	"${font_hfill[@]}"
	# 3 "multiplier" blocks
	"31,31,31,31,31,17,17,31"
	"31,31,31,17,17,17,17,31"
	"31,17,17,17,17,17,17,31"
)

printfx1() {
	value="$1"
	if [ $value -eq 0 ]; then
		value=1
	fi
	printf %02x $value
}

# printf format string...
out=
# ... and printf arguments
declare -a outargs=()
okempty=no
#set -x
while [ $# -gt 0 ]; do
	i="$1"
	shift
	c="${i#-}"
	if [ "$c" = "$i" ]; then
		out+="%s"
		#TODO: support incoming hex
		outargs+=("$i")
	elif [ "${cmd["$c"]+xxx}" ]; then
		out+="${cmd["$c"]}"
		if [ "${cmdargs["$c"]+xxx}" ]; then
			if [ $# -lt ${cmdargs["$c"]} ]; then
				echo "Not enough args to '$c'" 1>&2
				exit 1
			fi
			for ((a=0;a<${cmdargs["$c"]};++a)); do
				out+="\\x$(printfx1 "$1")"
				shift
			done
		fi
	elif [ "$c" = "msg" ]; then
		out+="%s"
		#TODO: support incoming hex
		outargs+=("$1")
		shift
	elif [ "$c" = "hex" ]; then
		out+="\\x$1"
		shift
	elif [ "$c" = "font" ]; then
		declare -n fvar="font_$1"
		shift
		for ((j=0;j<${#fvar[@]};++j)); do
			# font entries are 0-7, but bash can't hold 0 in a string
			out+="${cmd[customchar]}\\x$j"
			for r in ${fvar[$j]//,/ } ; do
				out+="\\x$(printfx1 $r)"
			done
		done
	elif [ "$c" = "loadbar" ]; then
		n="$1"
		shift
		declare -a lavgargs=()
		lavg=$(cut -d. -f1 < /proc/loadavg)
		lavgt=$(cat /proc/loadavg | cut -d. -f2 | cut -c 1)
		loffset=0
		nn="$n"
		while [ $lavg -gt $n -a $nn -ge 5 ]; do
			loffset=$((loffset + 5))
			lavg=$((lavg - 5))
			# 5, 10, 15 each are one char
			n=$((nn - (loffset + 14)/15))
		done
		while [ $loffset -gt 0 ]; do
			if [ $loffset -ge 15 ]; then
				out+='\x7'
				loffset=$((loffset - 15))
			elif [ $loffset -eq 10 ]; then
				out+='\x6'
				loffset=$((loffset - 10))
			elif [ $loffset -eq 5 ]; then
				out+='\x5'
				loffset=$((loffset - 5))
			else
				echo "WTF?!" 1>&2
				exit 1
			fi
		done
		for ((j=0;j<$n;++j)); do
			if [ $lavg -lt $j ]; then
				out+=' '
			elif [ $lavg -gt $j ]; then
				out+='\x4'
			elif [ $lavgt -ge 8 ]; then
				out+='\x3'
			elif [ $lavgt -ge 6 ]; then
				out+='\x2'
			elif [ $lavgt -ge 4 ]; then
				out+='\x1'
			elif [ $lavgt -ge 2 ]; then
				out+='\x0'
			else
				out+=' '
			fi
		done
	elif [ "$c" = "help" ]; then
		echo "Usage: $(basename "$0") [-cmd|message]..."
		echo "Commands:"
		for k in "${!cmd[@]}" ; do
			a=${cmdargs["$k"]}
			if [ -z "$a" ]; then
				echo "  $k"
			else
				echo "  $k ($a args)"
			fi
		done
		echo "  -msg <message>"
		echo "  -help"
		echo "  -testdev"
		echo "  -hex <hexchar>"
		echo "  -font <name>"
		exit 0
	elif [ "$c" = "testdev" ]; then
		okempty=yes
		if [ ! -e "$dev" ]; then
			exit 1
		fi
	elif [ "$c" = "powermode" ]; then
		okempty=yes
		if [ ! -e "$dev" ]; then
			exit 1
		fi
		devshortname=$(basename $(realpath "$dev"))
		sysbase=/sys/class/tty/$devshortname/device/
		powermodechanged=no
		for sysp in $(find $sysbase -type f -path '**/power/control') ; do
			[ "$(<$sysp)" != "on" ] || continue
			echo "set power $sysp on"
			echo on | sudo sponge $sysp
			powermodechanged=yes
		done
		# if it was in suspend mode, it generally needs a reset to work again
		if [ "$powermodechanged" = "yes" ]; then 
			sudo usbreset 239a:0001
			for sysp in $(find $sysbase -type f -path '**/power/control') ; do
				[ "$(<$sysp)" != "on" ] || continue
				echo "set power $sysp on"
				echo on | sudo sponge $sysp
				powermodechanged=yes
			done
		fi
	else
		echo "Unrecognized argument '$i'" 1>&2
		exit 1
	fi
done
#set +x

if [ -z "$out" ]; then
	if [ "$okempty" != "yes" ]; then
		echo "Gimme some args" 1>&2
		exit 1
	else
		exit 0
	fi
fi

#printf "$out" "${outargs[@]}" | hd
printf "$out" "${outargs[@]}" > $dev

lcdclock.service

[Unit]
Description=LCD Clock

[Service]
Type=simple
Environment="PATH=/usr/lib/ccache:%h/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/local/games:/usr/games"
ExecStart=%h/bin/lcdclock.sh
Restart=on-failure

[Install]
WantedBy=default.target

lcdclock.sh

#!/bin/bash

if [ ! -t 0 -a -z "$DIDSETSID" -a -z "$INVOCATION_ID" ]; then
	export DIDSETSID=1
	exec setsid nohup "$0" "$@" </dev/null &>/dev/null
	exit 1
fi

#set -x

lcd="$(dirname "$(realpath "$0")")"/lcd.sh

# don't hold open dirs or such
cd /

# line just wraps via careful counting
format="+%b %d  %H:%M:%S"

export lockfile=/run/user/$UID/lcdclock.lock
ltouch=

cleanup() {
	"$lcd" -clear -white -brightness 255 -off
	if [ -n "$ltouch" ]; then
		kill $ltouch
	fi
}

if ! lockfile-create --use-pid --retry 0 --lock-name $lockfile &>/dev/null ; then
	[ ! -t 0 ] || echo "Cannot get lock"
	exit 1
fi
lfpid=$BASHPID

trap cleanup EXIT

lockfile-touch --lock-name $lockfile &
ltouch=$!

sleep=
#shorthost="${HOSTNAME:-$(hostname -s)}"
#shorthost="$(printf "%-7s" "${shorthost:0:7}")"
for ((i=1;;++i)); do
	[ "$sleep" ] && sleep $sleep
	# don't stomp on other lcd usage
	if false ; then
		sleep=10
		i=0
		continue
	fi
	sleep=0.25
	if [ $i -eq 1 -o $i -gt 300 ]; then
		[ $i -gt 1 ] && i=0
		# reset lcd after stolen or every 5 minutes in case it's messed up
		# if this fails, retry lcd cleanup on next round
		"$lcd" -testdev -clear -on -white -brightness 3 -powermode -font loadbars || {
			i=0
			continue
		}
	fi
	lcd.sh -testdev -gohome -msg "$(date "$format")" -loadbar 16 || i=0
	
	if [ $((i % 4)) -eq 0 ] && ! lockfile-check --use-pid --lock-name $lockfile || [ "$(<$lockfile)" != "$lfpid" ] ; then
		[ ! -t 0 ] || echo "Another instance stole our lock!"
		exit 1
	fi
done

whiterose.sh

#!/bin/bash

bmax=3
gmod=60
ymod=30
rmod=15
gmax=$gmod
ymax=$((gmod + ymod))

zero=$(date +%s)
lnow=-1
lnows=-1
lcolor=null
fmod=0
while true ; do
	now=$(($(date +%s) - zero))
	if [ $now -lt $gmax ]; then
		color=green
		mod=$gmod
	elif [ $now -lt $ymax ]; then
		color=yellow
		mod=$ymod
	else
		color=red
		mod=$rmod
	fi
	nows=$((now % mod))
	bmod=$((fmod % 2))
	if [ $nows -eq 0 -a $lnows -ne $nows ]; then
		[ $lcolor = null ] || echo
		echo -n "$color "
		lcolor=$color
	fi
	if [ $nows -lt $bmax ]; then
		if [ $bmod -eq 0 ] ; then
			lcd.sh -$color -brightness 255
		else
			lcd.sh -white -brightness 3
		fi
	elif [ $nows -eq $bmax ]; then
		lcd.sh -white -brightness 3
	fi
	if [ $lnow -ne $now ]; then
		p=.
	else
		p=
	fi
	if read -t 0.3 -p "$p" ; then
		zero=$(date +%s)
		fmod=0
	else
		let fmod+=1
	fi
	lnow=$now
	lnows=$nows
done