From 1874cb71a62ee17d720d106a58ab684263abaa20 Mon Sep 17 00:00:00 2001
From: Erik van der Zalm <erik@vdzalm.eu>
Date: Wed, 2 May 2012 19:26:14 +0200
Subject: [PATCH] Added option to increase the FAN PWM frequency.

---
 Marlin/Configuration.h |  5 ++-
 Marlin/Marlin.h        |  4 +++
 Marlin/Marlin.pde      | 71 ++++++++++++++++++++++++++++++++++++++++++
 Marlin/temperature.cpp |  3 ++
 4 files changed, 82 insertions(+), 1 deletion(-)

diff --git a/Marlin/Configuration.h b/Marlin/Configuration.h
index cd1490a1c..f15876770 100644
--- a/Marlin/Configuration.h
+++ b/Marlin/Configuration.h
@@ -8,7 +8,7 @@
 //User specified version info of THIS file to display in [Pronterface, etc] terminal window during startup.
 //Implementation of an idea by Prof Braino to inform user that any changes made
 //to THIS file by the user have been successfully uploaded into firmware.
-#define STRING_VERSION_CONFIG_H "2012-02-25" //Personal revision number for changes to THIS file.
+#define STRING_VERSION_CONFIG_H "2012-05-02" //Personal revision number for changes to THIS file.
 #define STRING_CONFIG_H_AUTHOR "erik" //Who made the changes.
 
 // This determines the communication speed of the printer
@@ -230,6 +230,9 @@ const bool Z_ENDSTOPS_INVERTING = true; // set to true to invert the logic of th
   #endif
 #endif
 
+// Increase the FAN pwm frequency. Removes the PWM noise but increases heating in the FET/Arduino
+#define FAST_PWM_FAN
+
 // M240  Triggers a camera by emulating a Canon RC-1 Remote
 // Data from: http://www.doc-diy.net/photo/rc-1_hacked/
 // #define PHOTOGRAPH_PIN     23
diff --git a/Marlin/Marlin.h b/Marlin/Marlin.h
index d1169f4ef..5bb728c6f 100644
--- a/Marlin/Marlin.h
+++ b/Marlin/Marlin.h
@@ -170,6 +170,10 @@ bool IsStopped();
 void enquecommand(const char *cmd); //put an ascii command at the end of the current buffer.
 void prepare_arc_move(char isclockwise);
 
+#ifdef FAST_PWM_FAN
+void setPwmFrequency(uint8_t pin, int val);
+#endif
+
 #ifndef CRITICAL_SECTION_START
   #define CRITICAL_SECTION_START  unsigned char _sreg = SREG; cli();
   #define CRITICAL_SECTION_END    SREG = _sreg;
diff --git a/Marlin/Marlin.pde b/Marlin/Marlin.pde
index 8be47f8b7..1f2908766 100644
--- a/Marlin/Marlin.pde
+++ b/Marlin/Marlin.pde
@@ -36,6 +36,7 @@
 #include "watchdog.h"
 #include "EEPROMwrite.h"
 #include "language.h"
+#include "pins_arduino.h"
 
 #define VERSION_STRING  "1.0.0 RC2"
 
@@ -1512,4 +1513,74 @@ void Stop()
 
 bool IsStopped() { return Stopped; };
 
+#ifdef FAST_PWM_FAN
+void setPwmFrequency(uint8_t pin, int val)
+{
+  val &= 0x07;
+  switch(digitalPinToTimer(pin))
+  {
+ 
+    #if defined(TCCR0A)
+    case TIMER0A:
+    case TIMER0B:
+         TCCR0B &= ~(CS00 | CS01 | CS02);
+         TCCR0B |= val;
+         break;
+    #endif
+
+    #if defined(TCCR1A)
+    case TIMER1A:
+    case TIMER1B:
+         TCCR1B &= ~(CS10 | CS11 | CS12);
+         TCCR1B |= val;
+         break;
+    #endif
+
+    #if defined(TCCR2)
+    case TIMER2:
+    case TIMER2:
+         TCCR2 &= ~(CS10 | CS11 | CS12);
+         TCCR2 |= val;
+         break;
+    #endif
+
+    #if defined(TCCR2A)
+    case TIMER2A:
+    case TIMER2B:
+         TCCR2B &= ~(CS20 | CS21 | CS22);
+         TCCR2B |= val;
+         break;
+    #endif
+
+    #if defined(TCCR3A)
+    case TIMER3A:
+    case TIMER3B:
+    case TIMER3C:
+         TCCR3B &= ~(CS30 | CS31 | CS32);
+         TCCR3B |= val;
+         break;
+    #endif
+
+    #if defined(TCCR4A) 
+    case TIMER4A:
+    case TIMER4B:
+    case TIMER4C:
+         TCCR4B &= ~(CS40 | CS41 | CS42);
+         TCCR4B |= val;
+         break;
+   #endif
+
+    #if defined(TCCR5A) 
+    case TIMER5A:
+    case TIMER5B:
+    case TIMER5C:
+         TCCR5B &= ~(CS50 | CS51 | CS52);
+         TCCR5B |= val;
+         break;
+   #endif
+
+  }
+}
+#endif
+
 
diff --git a/Marlin/temperature.cpp b/Marlin/temperature.cpp
index 783aa232d..e21bd2598 100644
--- a/Marlin/temperature.cpp
+++ b/Marlin/temperature.cpp
@@ -559,6 +559,9 @@ void tp_init()
   #endif  
   #if (FAN_PIN > -1) 
     SET_OUTPUT(FAN_PIN);
+    #ifdef FAST_PWM_FAN
+    setPwmFrequency(FAN_PIN, 1); // No prescaling. Pwm frequency = F_CPU/256/8
+    #endif
   #endif  
 
   #ifdef HEATER_0_USES_MAX6675