Added exponential brightness to PWM conversion

docs/protocol.md

@@ -87,14 +87,14 @@ Modes
 Sets all steps to the same brightness.
 
 Parameters:<br>
-**brightness** (word): value in range 0 (off) to 4096 (fully on).
+**brightness** (word): value in range 0 (off) to 4095 (fully on).
 
 
 ### Custom
 Sets the brightness for each of the steps individually.
 
 Parameters:<br>
-**brightness** (word[stepCount]): array of brightness values in range 0 - 4096. The number of values must be equal to the number of steps are reported in the Ping response. Bottom step first.
+**brightness** (word[stepCount]): array of brightness values in range 0 - 4095. The number of values must be equal to the number of steps are reported in the Ping response. Bottom step first.
 
 
 ### Alternate
@@ -102,7 +102,7 @@ Alternates between even and odd steps being lit. Bring out our next contestant!
 
 Parameters:<br>
 **interval** (word): The time each set of steps is lit in milliseconds.<br>
-**brightness** (word): value in range 0 (off) to 4096 (fully on).
+**brightness** (word): value in range 0 (off) to 4095 (fully on).
 
 
 ### Slide

src/components/PCA9685.h

@@ -20,7 +20,7 @@ class PCA9685
 
   public:
     static const uint16_t Off = 0;
-    static const uint16_t On = 4096;
+    static const uint16_t On = 4095;
 
     static const uint8_t RegisterMode1 = 0x0;
     static const uint8_t RegisterPrescale = 0xFE;

src/main.cpp

@@ -47,18 +47,18 @@ void setup()
 
 
   // Run a little startup test sequence
-  pwmDriver->setAll(PCA9685::Off);
-  pwmDriver->setPWM(0, PCA9685::On);
+  stairs->setAll(IStairs::Off);
+  stairs->set(0, IStairs::On);
   delay(300);
 
   for (int step = 1; step < StepCount; step++)
   {
-    pwmDriver->setPWM(step - 1, PCA9685::Off);
-    pwmDriver->setPWM(step, PCA9685::On);
+    stairs->set(step - 1, IStairs::Off);
+    stairs->set(step, IStairs::On);
     delay(300);
   }
 
-  pwmDriver->setPWM(StepCount - 1, PCA9685::Off);
+  stairs->set(StepCount - 1, IStairs::Off);
 
 
   // Pulsate the bottom step while WiFi is connecting
@@ -71,7 +71,7 @@ void setup()
     if (brightness <= 0 || brightness >= 1024)
       speed = -speed;
 
-    pwmDriver->setPWM(0, brightness);
+    stairs->set(0, brightness);
     delay(16);
   }
 
@@ -84,7 +84,15 @@ void setup()
 
 
 uint32_t currentTime;
-uint8_t packet[51];
+
+// Note: the packet size must at least be able to accomodate the
+// command with the largest parameter list, there is no overflow
+// checking in the mode classes!
+//
+// At the time of writing, CustomMode is the largest:
+//    Set Mode (1) + Custom (1) + StepCount * Word (2)
+//    = 30 for 14 steps
+uint8_t packet[50];
 uint8_t* packetRef;
 
 void loop()
@@ -101,12 +109,11 @@ void checkRequest()
   int packetSize = udpServer.parsePacket();
   if (packetSize)
   {
+    memset(packet, 0, sizeof(packet));
     int length = udpServer.read(packet, 50);
     if (length && packet[0])
     {
-      packet[length] = 0;
       packetRef = packet;
-
       handleRequest(packetRef);
     }
   }
@@ -147,6 +154,7 @@ void handleRequest(uint8_t* packet)
         newMode->read(packet);
 
         udpServer.write(Command::SetMode);
+        udpServer.write(newIdentifier);
         newMode->write(&udpServer);
 
         setCurrentMode(newMode, newIdentifier);

src/mode.h

@@ -8,6 +8,9 @@
 class IStairs
 {
   public:
+    static const uint16_t Off = 0;
+    static const uint16_t On = 4095;
+
     virtual uint8_t getCount() = 0;
     virtual void set(uint8_t step, uint16_t value) = 0;
     virtual void setAll(uint16_t value) = 0;

src/modes/alternate.h

@@ -23,7 +23,7 @@ class AlternateMode : public BaseMode<AlternateModeParameters>
     AlternateMode()
     {
       parameters.interval = 500;
-      parameters.brightness = 4096;
+      parameters.brightness = IStairs::On;
     }
 
     void init(IStairs* stairs, uint32_t currentTime);

src/modes/custom.cpp

@@ -0,0 +1,29 @@
+#include "custom.h"
+#include <stdint.h>
+
+
+void CustomMode::read(uint8_t* data)
+{
+  // The packet is zeroed before we get our hands on it and
+  // the size should also be larger as noted in main.cpp,
+  // so a straight-up copy should be safe.
+  memcpy(this->values, data, sizeof(this->values));
+}
+
+
+void CustomMode::write(Stream* stream)
+{
+  stream->write(reinterpret_cast<uint8_t*>(&this->values), sizeof(this->values));
+}
+
+
+void CustomMode::init(IStairs* stairs, uint32_t currentTime)
+{
+  for (uint8_t step = 0; step < StepCount; step++)
+    stairs->set(step, this->values[step]);
+}
+
+
+void CustomMode::tick(IStairs* stairs, uint32_t currentTime)
+{
+}

src/modes/custom.h

@@ -9,6 +9,13 @@ class CustomMode : public IMode
 {
   private:
     uint16_t values[StepCount];
+
+  public:
+    void read(uint8_t* data);
+    void write(Stream* stream);
+
+    void init(IStairs* stairs, uint32_t currentTime);
+    void tick(IStairs* stairs, uint32_t currentTime);
 };
 
 #endif

src/stairs.cpp

@@ -1,6 +1,11 @@
+#include <Math.h>
 #include "stairs.h"
 #include "config.h"
 
+
+static const float brightnessFactor = ((IStairs::On - IStairs::Off) + 1) * log10(2) / log10(PCA9685::On);
+
+
 void Stairs::init(PCA9685* pwmDriver)
 {
   this->pwmDriver = pwmDriver;
@@ -13,13 +18,24 @@ uint8_t Stairs::getCount()
 }
 
 
-void Stairs::set(uint8_t step, uint16_t value)
+void Stairs::set(uint8_t step, uint16_t brightness)
 {
-  pwmDriver->setPWM(step, value);
+  pwmDriver->setPWM(step, this->getPWMValue(brightness));
 }
 
 
-void Stairs::setAll(uint16_t value)
+void Stairs::setAll(uint16_t brightness)
 {
-  pwmDriver->setAll(value);
+  pwmDriver->setAll(this->getPWMValue(brightness));
+}
+
+
+uint16_t Stairs::getPWMValue(uint16_t brightness)
+{
+  if (brightness == IStairs::Off || brightness == IStairs::On)
+    return brightness;
+
+  // Correct for the exponential perception of brightness
+  // Source: https://diarmuid.ie/blog/pwm-exponential-led-fading-on-arduino-or-other-platforms/
+  return pow(2, (brightness / brightnessFactor)) - 1;
 }

src/stairs.h

@@ -9,12 +9,15 @@ class Stairs : public IStairs
   private:
     PCA9685* pwmDriver;
 
+  protected:
+    uint16_t getPWMValue(uint16_t brightness);
+
   public:
     void init(PCA9685* pwmDriver);
 
     uint8_t getCount();
-    void set(uint8_t step, uint16_t value);
-    void setAll(uint16_t value);
+    void set(uint8_t step, uint16_t brightness);
+    void setAll(uint16_t brightness);
 };
 
 #endif

web/app.js

@@ -9,6 +9,32 @@ function lsb(value) { return value & 0xFF; }
 function msb(value) { return (value >> 8) & 0xFF; }
 
 
+
+
+/*
+Alternating
+
+var message = new Buffer([protocol.Command.SetMode, protocol.Mode.Alternate, lsb(500), msb(500), lsb(128), msb(128)]);
+client.send(message, 0, message.length, 3126, '10.138.2.12', function(err, bytes) {
+    if (err) throw err;
+    console.log('UDP message sent');
+});
+*/
+
+
+var client = dgram.createSocket('udp4');
+client.on('listening', function()
+{
+  var address = client.address();
+  console.log('UDP client listening on ' + address.address + ":" + address.port);
+});
+
+client.on('message', function (message, remote)
+{
+  console.log('< ' + remote.address + ':' + remote.port +' - ' + message.toString('hex'));
+});
+
+
 setInterval(function()
 {
   // 0x00, 0x10 = 4096
@@ -17,21 +43,8 @@ setInterval(function()
     speed = -speed;
 
   var message = new Buffer([protocol.Command.SetMode, protocol.Mode.Static, lsb(on), msb(on)]);
-  var client = dgram.createSocket('udp4');
-  client.on('listening', function()
-  {
-    var address = client.address();
-    console.log('UDP client listening on ' + address.address + ":" + address.port);
-  });
-
-  client.on('message', function (message, remote)
-  {
-    console.log(remote.address + ':' + remote.port +' - ' + message.toString('hex'));
-    client.close();
-  });
-
   client.send(message, 0, message.length, 3126, '10.138.2.12', function(err, bytes) {
       if (err) throw err;
-      console.log('UDP message sent');
+      console.log('> ' + '10.138.2.12' + ':' + '3126' + ' - ' + message.toString('hex'));
   });
 }, 200);