variable PWM step calculation

src/main.cpp

 uint32_t m=0;
 
 uint32_t dimmtimer = 0; 
+uint16_t time_per_stair = 500;    // global parameter: dimmtime per stair [ms]
 uint8_t direction = 1;
 uint8_t onoff = 1;
 
 
-void ledsequence(uint8_t direction, uint8_t onoff, uint8_t factor);
-uint8_t softstart_led(uint8_t led, uint16_t startval, uint16_t stopval, uint8_t factor);
+void ledsequence(uint8_t direction, uint8_t onoff);
+uint8_t softstart_led(uint8_t led, uint16_t startval, uint16_t stopval);
 
 void timerCallback(void *pArg)
 {
   *((int *) pArg) += 1;
   
-  ledsequence(direction, onoff, 4);
+  ledsequence(direction, onoff);
   // Serial.print("[");
   // Serial.print(micros()-m);
   // Serial.print("] timerCallback\n");
   pinMode(ESP12_LED, OUTPUT);
 
   Wire.begin();                       // Wire must be started first
-  Wire.setClock(400000);              // Supported baud rates are 100kHz, 400kHz, and 1000kHz
+  Wire.setClock(1000000);              // Supported baud rates are 100kHz, 400kHz, and 1000kHz
 
   WiFi.mode(WIFI_STA);
   WiFi.begin(ssid, password);
   }
 
   os_timer_setfn(&Timer1, timerCallback, &c);
-  os_timer_arm(&Timer1, 1, true);
+  os_timer_arm(&Timer1, 20, true);
 
 
   Serial.println("Ready");
 #define SP_US(_str,_a) Serial.print(_str); Serial.print(" took: "); Serial.print(_a); Serial.println("µs")
 #define TIMEIF_US(_str,_f, _l) t=micros(); _f; t=micros()-t; if(t > _l) { SP_US(_str, t); }
 
-uint8_t softstart_led(uint8_t led, uint16_t startval, uint16_t stopval, uint8_t factor){
+uint8_t softstart_led(uint8_t led, uint16_t startval, uint16_t stopval){
+
+  /*
+  softstart task
+
+  - get's called at regular intervals (1ms at the moment)
+  - dimms single led (0 - 15, PCA9685 outputs) with linear intervals vom startval to stopval
+  - calculates pwm steps depending on startval, stopval and timeinterval
+  - -> results in constanst speed
+  - returns 1 if led dimming is running
+  - returns 0 if led dimming is finished
+
+  */
+
     static uint8_t lastled = 255;
-    static uint8_t current_pwm = 0;
-    
+    static float current_pwm = 0;
+    static float stepsize = 1.0;
     if(led != lastled){
-      pwmController.setChannelPWM(led, startval);
+      pwmController.setChannelPWM(led, (uint16_t)startval);
       lastled = led;
       current_pwm = startval;
+      stepsize = 20*abs(stopval - startval)/(float)time_per_stair;      // only valid at 1ms function call interval
       return 1;
     }
     
-    if(current_pwm == stopval){
-      return 0;
-    } 
-
-    else if(startval > stopval){
-      current_pwm -= 1;
+    if(current_pwm > stopval - stepsize && current_pwm < stopval + stepsize) return 0;
+    // todo: duty cycle zero!
+    if(startval > stopval){
+      current_pwm -= stepsize;
     }
     else {
-      current_pwm += 1;
+      current_pwm += stepsize;
     }
-    pwmController.setChannelPWM(led, current_pwm*factor);
+    Serial.println((uint16_t)current_pwm);
+    pwmController.setChannelPWM(led, (uint16_t)current_pwm);
     return 1;
 }
 
 #define LEDCOUNT 16
 
-void ledsequence(uint8_t direction, uint8_t onoff, uint8_t factor){
+void ledsequence(uint8_t direction, uint8_t onoff){
   static int8_t led = 0;
-  static uint8_t brightness = 0;
-  static uint8_t lastbrightness = 0;
+  static uint16_t brightness = 0;
+  static uint16_t lastbrightness = 0;
   static uint8_t finish = 1;
-  static uint32_t status = 0;
-  uint32_t status_build = 0;
-  status_build |= direction << 16;
-  status_build |= onoff << 8;
-  status_build |= factor;
+  static uint16_t status = 0;
+  uint16_t status_build = 0;
+  status_build |= direction << 8;
+  status_build |= onoff;
   if(status_build != status){                 // check if any parameter changed
     finish = 0;                               // set state unfinished -> start action
     if(direction) led = 0;                    // reset led counter depending of direction
     else          led = LEDCOUNT-1;
     if(onoff){
-      brightness = 127;           // set brightness value depending of on/off
-      lastbrightness = 0;
+      brightness = 2048;           // set brightness value depending of on/off
+      lastbrightness = 200;
     }     
     else{
-      brightness = 0;
-      lastbrightness = 127;
+      brightness = 200;
+      lastbrightness = 2048;
     }          
     status = status_build;                    // set parameter memory
     Serial.print("----Status Changed! onoff: ");
 
   }
   if(!finish){                                // finish == 0 -> action pending
-      if(!softstart_led(led,lastbrightness, brightness, factor)){
-        Serial.print("one LED finished, new set led: ");
+      if(!softstart_led(led,lastbrightness, brightness)){
+        Serial.print("one LED finished: ");
         Serial.print(led);
         Serial.print(" last: ");
         Serial.print(lastbrightness);
 void loop() {
 
   
-
-  if(millis() - dimmtimer > 2){
-    //ledsequence(direction, onoff, 4);
-    dimmtimer = millis();
-  }
   if(millis() > 25000 && onoff == 1 && direction == 1) onoff = 0;
-  if(millis() > 35000 && direction == 1){
+  if(millis() > 45000 && direction == 1){
     onoff = 1;
     direction = 0;    
   }
+  
+
   TIMEIF_US("OTA", ArduinoOTA.handle(), 1000);
   TIMEIF_US("HTTP", server.handleClient(), 1000);
 }