add devterm_fan_daemon_cm4 script

Code/devterm_fan_daemon_cm4/README.md

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+# Fan control daemon for devterm cm4(rpi os)
+ 
+## Install
+
+**Devterm is pre-installed this package, so devterm cm4 users do not need to repeat the installation steps**
+
+```
+wget -O - https://raw.githubusercontent.com/clockworkpi/apt/main/debian/KEY.gpg | sudo apt-key add -
+echo "deb https://raw.githubusercontent.com/clockworkpi/apt/main/debian/ stable main" | sudo tee -a /etc/apt/sources.list.d/clockworkpi.list
+
+sudo apt update && apt install -y devterm-fan-temp-daemon-cm4
+```
+
+## Change the threshold temperature
+
+Edit `/usr/local/bin/temp_fan_daemon.py`
+
+line starts with `MAX_TEMP=80`
+
+For devterm cm4(rpi os) the  recommended MAX_TEMP is in range 60-80 
+
+then restart systemd service to take effect
+
+`sudo systemctl restart devterm-fan-temp-daemon`
+
+

Code/devterm_fan_daemon_cm4/etc/systemd/system/devterm-fan-temp-daemon.service

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+[Unit]
+Description=devterm raspberry pi cm4 fan control daemon
+
+[Service]
+Type=simple
+ExecStart=/usr/bin/python3 /usr/local/bin/temp_fan_daemon.py
+
+
+[Install]
+WantedBy=multi-user.target

Code/devterm_fan_daemon_cm4/temp_fan_daemon.py

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+###devterm raspberry pi fan control daemon
+import os
+import time
+
+
+def isDigit(x):
+    try:
+        float(x)
+        return True
+    except ValueError:
+        return False
+
+def measure_temp():
+    temp = os.popen("/opt/vc/bin/vcgencmd measure_temp").readline()
+    temp2 = temp.replace("temp=","")
+    temp3 = temp2.replace("'C","").strip()
+    #print(temp3)
+    if isDigit(temp3):
+        return float(temp3)
+    else:
+        return 0
+
+
+def init_fan_gpio():
+    os.popen("gpio mode 17 out")
+
+def fan_on():
+    init_fan_gpio()
+    os.popen("gpio write 17 1")
+
+def fan_off():
+    init_fan_gpio()
+    os.popen("gpio write 17 0")
+
+
+MAX_TEMP=80
+
+init_fan_gpio()
+
+while True:
+    temp =  measure_temp()
+    if(temp > MAX_TEMP):
+        fan_on()
+    else:
+        fan_off()
+    
+    time.sleep(5)
+
+
+
+