Exponential smoothing on expression pedal ADC (factor 8) to filter noise

include/expression_pedal.h

@@ -29,6 +29,7 @@ private:
     uint32_t last_read_time;
 
     uint16_t current_raw;
+    uint16_t smoothed_raw;
     uint16_t cal_min;
     uint16_t cal_max;