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diff --git a/README.md b/README.md
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+# armbian-envtemp-cpufreq
+
+Adjust maximum CPU frequency based on environment temperature.
+Works with [temphumd](https://git.ch1p.io/homekit.git/tree/src/temphumd.py) server.
+
+## Config example
+
+```
+# roof temphumd server
+192.168.1.2:8306
+
+# you can get available frequencies
+# from /sys/devices/system/cpu/cpufreq/policy0/scaling_available_frequencies
+
+# temp freq
+21 1800000   
+24 1704000
+28 1608000
+32 1320000
+36 1080000
+40 888000
+```
diff --git a/armbian-envtemp-cpufreq.sh b/armbian-envtemp-cpufreq.sh
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+#!/bin/bash
+
+set -e
+
+PROGNAME="$0"
+
+config=
+temphumd_host=
+temphumd_port=
+
+declare -a values
+
+die() {
+	>&2 echo "error: $@"
+	exit 1
+}
+
+read_config() {
+	local config_file="$1"
+	local words
+	local temp
+	local freq
+	local line
+	local n
+
+	n=0
+	while read line; do
+		n=$(( n+1 ))
+		
+		# skip empty lines or comments
+		if [ -z "$line" ] || [[ "$line" =~ ^#.*  ]]; then
+			continue
+		fi
+
+		if [ -z "$temphumd_host" ] || [ -z "$temphumd_port" ]; then
+			temphumd_host=$(extract_ip "$line")
+			temphumd_port=$(extract_port "$line")
+		else
+			words=($line)
+
+			temp=${words[0]}
+			freq=${words[1]}
+
+			if [ -z "$temp" ] || [ -z "$freq" ]; then
+				die "config: line $n is invalid"
+			fi
+
+			values[$temp]=$freq
+		fi
+	done < <(cat "$config_file")
+}
+
+extract_ip() {
+	echo "$1" | sed -e 's/:.*$//g'
+}
+
+extract_port() {
+	echo "$1" | sed -e 's/^.*://g'
+}
+
+usage() {
+	cat <<-_EOF 
+	usage: $PROGNAME [OPTIONS] COMMAND
+
+	Options:
+	    -c|--config CONFIG
+
+	_EOF
+	exit 1
+}
+
+[[ $# -lt 1 ]] && usage
+
+while [[ $# -gt 0 ]]; do
+	case $1 in
+		-c|--config)
+			config="$2"
+			shift; shift
+			;;
+
+		*)
+			die "unrecognized option $1"
+			exit 1
+			;;
+	esac
+done
+
+[ -z "$config" ] && die "missing required -c or --config"
+
+read_config "$config"
+
+# reading temperature from temphumd server
+exec 3<>/dev/tcp/$temphumd_host/$temphumd_port
+echo -n "read" >&3
+read -t 5 response <&3
+
+envtemp=$(echo "$response" | jq ".temp" | awk "{print int(\$1+0.5)}")
+
+# setting corresponding cpu freq
+while read temp; do
+	freq=${values[$temp]}
+	(( envtemp >= temp )) && break
+done < <(for temp in ${!values[@]}; do echo $temp; done | sort -rn)
+
+echo -n "$freq" > /sys/devices/system/cpu/cpufreq/policy0/scaling_max_freq
+echo "Environment temperature is $envtemp C, set max CPU frequency to $freq."