Adding in comments and reworking how temp is read from CPU

2 files changed, 50 insertions, 12 deletions

diff --git a/README.md b/README.md
new file mode 100644
index 0000000..d88c3ff
--- /dev/null
+++ b/README.md
@@ -0,0 +1,40 @@
+# rpi-temp-control
+
+A temperature monitor and control program for the Raspberry Pi's CPU. This is done by monitoring the reported temperature
+of the combined CPU and GPU package, which is fed into a PID loop that controls the speed of a fan mounted above it.
+
+I wrote this so my Pi would be quite when it is doing simple tasks, but would be able to enable a fan to cool the CPU
+when I need to compile things or surf the web.
+
+# Using
+
+To run this program, you are going to need root privileges but can be run by simply entering
+
+```
+# python rpi-temp-control.py
+``` 
+
+This will leave the program running forever, and you should notice the fan changing speed as the Pi gets warmer and
+cooler. At some point I will turn this into a proper daemon service that can be setup and forgotten about.
+
+There are only a couple of things that should be noted when using this, first that you need to connect a fan to the Pi
+in a safe way. You should NOT drive the fan from the gpio pins on the Pi directly, but instead the pin that this
+program controls should be some sort of enable line on either a power transistor or motor control board. The second
+thing is that this program is writing a pwm signal to that pin, which means the fan is really turning on and off quickly
+and may make not allow this program to work with motor controllers that use other methods to control motor speed. Also
+be aware that there is probably a minimum speed (or pulse rate) that the fan will work at, so the minimum fan speed
+may need to be tweaked because of that.
+
+Please don't expect this to solve all overheating issues your Pi may experience, this just a dumb PID loop. Really any
+Raspberry Pi 3 (at least in my experience) should have at least a heatsink on their CPU to help with limiting when
+thermal throttling will happen. A case or mounting for a fan should have enough airflow for the fan so it won't burn out
+the motor, but if the air the fan is moving across the CPU will limit how cool it can make the CPU.
+# Copyright and License
+
+2018 Matt Kohls
+GPL v3
+
+Based on the work by [rudybrian](https://github.com/rudybrian/PID_Fan_Control)
+
+This program is distributed in the hope it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty
+of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
\ No newline at end of file
diff --git a/rpi-temp-control.py b/rpi-temp-control.py
index d99824a..fb7f0aa 100644
--- a/rpi-temp-control.py
+++ b/rpi-temp-control.py
@@ -3,11 +3,14 @@
 ##
 # rpi-temp-control
 #
-#
+# Changes speed of system fan to try and control the CPU/GPU temperature. This is done through the use of a PID loop
+# that is targeting a specific temperature.
 #
 # Matt Kohls
+# 2018
+#
+# Licensed under GPL v3
 
-import subprocess
 from gpiozero import Motor
 from pid import PID
 from time import sleep
@@ -22,14 +25,10 @@ MIN_FAN_SPEED = 80 / 100
 #
 # @return temperature of GPU/CPU
 def grab_temp():
-    try:
-        file = open("/sys/class/thermal/thermal_zone0/temp", "r")
+    val = 0
+    with open("/sys/class/thermal/thermal_zone0/temp", "r") as file:
         val = int(file.readline()) / 1000
-        file.close()
-        return val
-    except:
-        print("Error reading from thermal zone")
-        return 0
+    return val
 
 # Initial loop setup
 ploop = PID(1, 1, .02, Integrator_max=100, Integrator_min=0, Set_Point=TEMP_TARGET)
@@ -42,9 +41,8 @@ last_temp = 0
 while True:
     sleep(1)
     temp = grab_temp()
-    print(temp)
-    cycle_change = (ploop.update(temp)) * -1
-    cycle = (100 + int(cycle_change)) / 100 # Since fan.forward() wants a number between 0 and 1
+    cycle_change = ploop.update(temp)
+    cycle = (100 - int(cycle_change)) / 100 # Since fan.forward() wants a number between 0 and 1
 
     if cycle <= .2:
         cycle = 0