Fancontrol via Hardware PWM for RaspberryPi

Fancontrol-hv2.c

/*
Fancontrol via Hardware PWM for Raspian
Author: 2h4u
Date: 19.01.2013

Version 2:
Now with dynamic PWM regulation!
*/

#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <sys/stat.h>
#include <stdlib.h>

#include <wiringPi.h>

//-------INIT-------//
int FAN = 1;
//------------------//
int PWM_ZERO = 550;
int PWM_MAX = 1024;
//------------------//
int TEMP_ZERO = 45000;
int TEMP_PWM = 50000;
int TEMP_MAX = 70000;
//---- getTemp -----//
FILE* tempfile;
int tempCache = 0;
//------ main ------//
int sleepTime = 5;
//------------------//

int getTemp ()
{
   // Read Temp
   tempfile = fopen ("/sys/class/thermal/thermal_zone0/temp", "r");
   fscanf (tempfile, "%d", &tempCache);
   fclose (tempfile);
   return tempCache;
}

int checkIfItsFirstRun ()
{
   struct stat st;
   int status = 0;
   
   // Check if there is a configfile
   if(stat ("/usr/share/fancontrol/config.txt",&st) == 0)
      return 0;
    else
    {   
       // if there is no configfile, check if there is the directory
      if(stat ("/usr/share/fancontrol",&st) == 0)
      {
         // create config.txt
         FILE *outfile = fopen ("/usr/share/fancontrol/config.txt", "a+");
         
          if(!outfile) {
              printf ("There was a problem opening /usr/share/fancontrol/config.txt for writing\n");
              fclose (outfile);
              return 1;
          }
          else
          {   // write standard config to config.txt
             fprintf (outfile,"%s","#FAN-PIN\n1\n#Min. PWM-POWER (0-1024):\n550\n#Max. PWM-POWER (0-1024):\n1024\n#Fan stops at Temp (°C *1000):\n45000\n#Fan starts at Temp:\n50000\n#Fullspeed Fan at Temp:\n70000\n#Refresh Time (seconds):\n5\n") ;
          }
          fclose (outfile);
          return 0;
      }
      else
      {
         // create fancontrol-dir + config.txt
         status = mkdir ("/usr/share/fancontrol", S_IRWXO) ;
         
         if(status != 0)
         {
            fprintf (stderr, "Unable to create /usr/share/fancontrol  %s\n", strerror (errno)) ;
            return status;
         }
         
         // now create the config.txt
         FILE *outfile = fopen ("/usr/share/fancontrol/config.txt", "a+");
         
          if(!outfile) {
              printf ("There was a problem opening /usr/share/fancontrol/config.txt for writing\n");
              fclose (outfile);
              return 1;
          }
          else
          {   // write standard config to config.txt
             fprintf (outfile,"%s","#FAN-PIN\n1\n#Min. PWM-POWER (0-1024):\n550\n#Max. PWM-POWER (0-1024):\n1024\n#Fan stops at Temp (°C *1000):\n45000\n#Fan starts at Temp:\n50000\n#Fullspeed Fan at Temp:\n70000\n#Refresh Time (seconds):\n5\n") ;
          }
          fclose (outfile);
          return 0;
      }
    }
}


int getConfig(void)
{
    char line[256];
    int wert = 0, linenum = 0 ;
    FILE* configfile = fopen ("/usr/share/fancontrol/config.txt", "r");
   
   while(fgets (line, 256, configfile) != NULL)
   {
         linenum++;
         if(line[0] == '#')
            continue;
      // now read the configfile
         if(sscanf (line, "%d", &wert) != 1)
       {
          fprintf (stderr, "Syntax error, line %d\n", linenum);
           continue;
       }
       // now allocate values
       switch( linenum )
      {
          case 2:
                FAN = wert;
              break;
          case 4 :
              PWM_ZERO = wert;
              break;
           case 6 :
              PWM_MAX = wert;
              break;
          case 8 :
              TEMP_ZERO = wert;
              break;
           case 10 :
              TEMP_PWM = wert;
              break;
           case 12 :
              TEMP_MAX = wert;
              break;
           case 14 :
              sleepTime = wert;
              break;
      }
      
   }
   fclose (configfile);

    return 0;
}


int main ()   
{
  // check if wiringPi loaded correctly
  if (wiringPiSetup () == -1)
     {
       fprintf (stderr, "Unable to setup GPIO: %s\n", strerror (errno)) ;
       return 1 ;
     }
 
  checkIfItsFirstRun ();
  getConfig ();
 
  pinMode (FAN, PWM_OUTPUT) ;
  int temp = 0, pwmPercentage = 0, fanStatus = 0;
  float tempOnePercent = 0, pwmOnePercent = 0, tempPercentage = 0, pwmPercentageDump = 0, tempDump = 0;
 
  // Precalculations
  tempOnePercent = ((TEMP_MAX - (float)TEMP_ZERO) / 100000) ;
  pwmOnePercent = ((PWM_MAX - (float)PWM_ZERO) / 100) ;
 
  printf( "FAN: %i \n", FAN);
  printf( "tempOnePercent: %f \n", tempOnePercent);
  printf( "pwmOnePercent: %f \n", pwmOnePercent);
  while(1)
  {
   temp = getTemp ();
   printf( "temp: %i \n", temp);
   
      if(temp > TEMP_PWM)
      {   
         while(temp > TEMP_ZERO)
         {   // Calculate the PWM-Power
            tempDump = ((temp - (float)TEMP_ZERO) / 1000) ;
            tempPercentage = tempDump / tempOnePercent ;
            pwmPercentageDump = tempPercentage * pwmOnePercent;
            pwmPercentage = (int)( (pwmPercentageDump + PWM_ZERO)) ;
            
            

            if(fanStatus == 0)
            {   // Help the Fan to start
               pwmWrite (FAN, PWM_MAX) ;
               fanStatus = 1;
               sleep (1) ;
            }
            pwmWrite (FAN, pwmPercentage) ;
            sleep (sleepTime) ;
            temp = getTemp ();
            
            printf( "\ntemp: %i \n", temp);
            printf( "pwmPercentage: %i \n", pwmPercentage);
            printf( "tempDump: %f \n", tempDump);
            printf( "tempPercentage: %f \n", tempPercentage);
            printf( "pwmPercentageDump: %f \n", pwmPercentageDump);
         }
      }
      else
      {
         pwmWrite (FAN, 0) ;
         fanStatus = 0;
         sleep (sleepTime) ;
      }   
  }
   
  return 0 ;
}
/*
To Compile:
gcc -Wall -o fancontrol-hv2 Fancontrol-hv2.c -lwiringPi -lpthread


To Run automaticly at startup write the follwing before "exit 0" in /etc/rc.local:
/location/of/fancontrol-hv2 &

*/

fancontrol.sh

#!/bin/bash
# Fancontrol via Hardware PWM for RaspberryPi
# Authors: Fernando Fernández, Iñaki Ucar
# Date: 18.08.2014

# Path
GPIO=/usr/local/bin/gpio

# Limits
MIN_TEMP=40
MAX_TEMP=69
MIN_FAN=0
MAX_FAN=1024

# Run forever
while [ 1 ]; do

	# What's the CPU temp?
	temp=$(cat /sys/class/thermal/thermal_zone0/temp)
	temp=$((temp/1000))
	
	# Variable temperature control
	if [ $temp -gt $MIN_TEMP  ] && [ $temp -lt $MAX_TEMP ]; then
		fan=$(((temp - MIN_TEMP) * MAX_FAN / (MAX_TEMP - MIN_TEMP)))
		secs=1

	# Maximum fan RPM
	elif [ $temp -ge $MAX_TEMP ]; then
		fan=$MAX_FAN
		secs=1

	# Switch off the fan
	else
		fan=$MIN_FAN
		secs=60
	fi
	
	$GPIO -g mode 18 pwm
	$GPIO -g pwm 18 $fan

	# Show current state and pause for a while
	echo "temp: $temp'C | fan: $((fan * 100 / MAX_FAN))% | pause: $secs""s"
	sleep $secs

done
exit 0

Source:

• C version
• Bash version