optional low pass filter for analog values

cimdithal.cpp

@@ -11,7 +11,6 @@
  
 // library includes
 #include <Adafruit_MCP23X17.h>
-
 // own includes
 #include "cimdithal.h"
 
@@ -109,6 +108,9 @@ void CimditHAL::readFromHardware(bool interrupt) {
     int16_t lastAnalogValue = m_currentAnalogValues[m_analogNum];
     // scan analog value
     m_currentAnalogValues[m_analogNum] = analogRead(ANALOG_IN);
+#ifdef ANALOG_LOW_PASS_FACTOR
+    m_currentAnalogValues[m_analogNum] = lastAnalogValue - (ANALOG_LOW_PASS_FACTOR * (lastAnalogValue - m_currentAnalogValues[m_analogNum]));
+#endif
     // set changed bits
     if (lastAnalogValue != m_currentAnalogValues[m_analogNum]) {
     //if (abs(lastAnalogValue - m_currentAnalogValues[m_analogNum]) > 1) {

defines.h

@@ -36,6 +36,9 @@
 /// dead zone (noise) around the center of the joystick Y axcs
 #define JOYSTICK_DEAD_ZONE_Y 20
 
+/// optional analog filtering higher values mean faster changer, but more noise
+#define ANALOG_LOW_PASS_FACTOR 0.95
+
 /// i2c address of the external EEPROM
 #define EXTERNAL_EEPROM 0x50