SimpleFilter.h

00001 /** SimpleFilter implements a simple low pass integer "leaky integrator" described here:
00002  * 
00003  * http://ece124web.groups.et.byu.net/references/readings/Simple%20Software%20Lowpass%20Filter.pdf
00004  *
00005  * Well suited for filtering ADC integer values very quickly
00006  *
00007  * Michael Shimniok http://bot-thoughts.com/
00008  */
00009 class SimpleFilter {
00010 public:
00011     /** Creates a new filter object
00012      *
00013      * @param shift: the number of shifts to perform at each filtering input step; lower means higher bandwidth
00014      */
00015     SimpleFilter(short shift);
00016 
00017     /** Supplies input to the filter and returns filtered output value
00018      *
00019      * @param value is the input value to the filter, e.g., some measurement
00020      * @returns the filtered output value
00021      */
00022     short filter(short value);
00023 
00024     /** Read the current value in the filter
00025      *
00026      * @returns the current value in the filter
00027      */
00028     short value(void);
00029 
00030     /** Shorthand operator for value()
00031      *
00032      * @returns the current value in the filter
00033      */
00034     operator short() { return value(); }
00035 
00036 private:
00037     long _filter_value;
00038     short _shift;
00039 };