Tweaks afters connecting an actual fan

Changed PWM frequency to reduce fan motor hum
Added minimum value
Added custom value entry in the test application

.gitignore

@@ -1,4 +1,5 @@
 AssettoCorsa/source/__history
 AssettoCorsa/*.dproj.local
+AssettoCorsa/*.identcache
 AssettoCorsa/bin
 AssettoCorsa/lib

AssettoCorsa/source/MainFrm.dfm

@@ -4,7 +4,7 @@ object MainForm: TMainForm
   BorderIcons = [biSystemMenu, biMinimize]
   BorderStyle = bsSingle
   Caption = 'SimulatorFans - Assetto Corsa'
-  ClientHeight = 309
+  ClientHeight = 390
   ClientWidth = 645
   Color = clBtnFace
   Font.Charset = DEFAULT_CHARSET
@@ -87,4 +87,29 @@ object MainForm: TMainForm
     TabOrder = 7
     OnClick = Button6Click
   end
+  object Edit1: TEdit
+    Left = 288
+    Top = 253
+    Width = 75
+    Height = 21
+    TabOrder = 8
+    Text = '0'
+  end
+  object Button7: TButton
+    Left = 288
+    Top = 280
+    Width = 171
+    Height = 25
+    Caption = 'Set'
+    TabOrder = 9
+    OnClick = Button7Click
+  end
+  object Edit2: TEdit
+    Left = 384
+    Top = 253
+    Width = 75
+    Height = 21
+    TabOrder = 10
+    Text = '0'
+  end
 end

AssettoCorsa/source/MainFrm.pas

@@ -22,6 +22,9 @@ type
     Button4: TButton;
     Button5: TButton;
     Button6: TButton;
+    Edit1: TEdit;
+    Button7: TButton;
+    Edit2: TEdit;
 
     procedure FormCreate(Sender: TObject);
     procedure RefreshPortsButtonClick(Sender: TObject);
@@ -31,6 +34,7 @@ type
     procedure Button4Click(Sender: TObject);
     procedure Button5Click(Sender: TObject);
     procedure Button6Click(Sender: TObject);
+    procedure Button7Click(Sender: TObject);
   private
     FComPort: TComPort;
     FReceived: string;
@@ -70,6 +74,7 @@ end;
 
 procedure TMainForm.Button2Click(Sender: TObject);
 begin
+  Edit1.Text := '255';
   SendCommand('>SetFans:255,0',
     procedure(Response: string)
     begin
@@ -80,6 +85,7 @@ end;
 
 procedure TMainForm.Button3Click(Sender: TObject);
 begin
+  Edit2.Text := '255';
   SendCommand('>SetFans:0,255',
     procedure(Response: string)
     begin
@@ -90,6 +96,8 @@ end;
 
 procedure TMainForm.Button4Click(Sender: TObject);
 begin
+  Edit1.Text := '0';
+  Edit2.Text := '0';
   SendCommand('>SetFans:0,0',
     procedure(Response: string)
     begin
@@ -100,6 +108,7 @@ end;
 
 procedure TMainForm.Button5Click(Sender: TObject);
 begin
+  Edit1.Text := '128';
   SendCommand('>SetFans:128,0',
     procedure(Response: string)
     begin
@@ -110,6 +119,7 @@ end;
 
 procedure TMainForm.Button6Click(Sender: TObject);
 begin
+  Edit2.Text := '128';
   SendCommand('>SetFans:0,128',
     procedure(Response: string)
     begin
@@ -118,9 +128,20 @@ begin
     end);
 end;
 
+procedure TMainForm.Button7Click(Sender: TObject);
+begin
+  SendCommand('>SetFans:' + Edit1.Text + ',' + Edit2.Text,
+    procedure(Response: string)
+    begin
+      if Response <> '<SetFans' then
+        ShowMessage('Invalid response: ' + Response);
+    end);
+end;
+
 procedure TMainForm.FormCreate(Sender: TObject);
 begin
   RefreshPorts;
+  PortComboBox.ItemIndex := Pred(PortComboBox.Items.Count);
 end;
 
 

SimulatorFans.ino

@@ -64,6 +64,10 @@ const byte FanPin[FanCount] =
 #define StartingFansTime 200
 
 
+// The minimum value at which the fan still spins reliably. Anything below
+// will be considered as 0.
+#define MinimumValue 32
+
 /*
  * Actual code. Lasciate ogne speranza, voi ch'intrate.
  */
@@ -94,6 +98,17 @@ void setup()
   for (byte fan = 0; fan < FanCount; fan++)
     pinMode(FanPin[fan], OUTPUT);
 
+  // Set all clock select bits to clk/1024. This will result in a 30 ~ 60 Hz PWM frequency. 
+  // The default frequency causes annoying noises in the fan, the low frequency is still
+  // audible but good enough since the game sounds should easily drown that out.
+  // It messes up the millis() function though, so compensate for that later on.
+  TCCR0B = TCCR0B & 0b11111000 | 0b101;
+  TCCR1B = TCCR1B & 0b11111000 | 0b101;
+  TCCR2B = TCCR2B & 0b11111000 | 0b101;
+
+  // 64 is the default prescaler
+  #define correctedMillis() (millis() * (1024 / 64))
+
   // Set up serial communication (through USB or the default pins)
   // 19.2k is fast enough for our purpose, and according to the ATMega's datasheet 
   // has a low error percentage across the common oscillator frequencies.
@@ -108,7 +123,7 @@ char* token;
 
 void loop() 
 {
-  currentTime = millis();
+  currentTime = correctedMillis();
   checkStartingFans();
 
   if (Serial.available() > 0)
@@ -202,7 +217,11 @@ void checkStartingFans()
 
 void setFan(byte fan, byte value)
 {
-  if ((fanStatus[fan].value == 0 || fanStatus[fan].startTime > 0) && value > 0)
+  byte correctedValue = value;
+  if (correctedValue < MinimumValue)
+    correctedValue = 0;
+  
+  if ((fanStatus[fan].value == 0 || fanStatus[fan].startTime > 0) && correctedValue > 0)
   {
     // Fan was off or still starting up, start with full power to kick it off
     analogWrite(FanPin[fan], 255);
@@ -216,9 +235,8 @@ void setFan(byte fan, byte value)
   {
     // Already running, simply change the speed and reset the start time if necessary
     fanStatus[fan].startTime = 0;
-    analogWrite(FanPin[fan], value);
+    analogWrite(FanPin[fan], correctedValue);
   }
   
-  fanStatus[fan].value = value;
+  fanStatus[fan].value = correctedValue;
 }
-