Moving-average-filter

Average filter based on FIFO buffer

Library files

Concept block

 input
+
|
+-----+ | S/H | <------------------ sampling time
+-----+ |
v
+------------------+--------------------+
index +-->+ DEMUX |
+----+------+------+----------------+---+
| | | |
+--+-+ +--+-+ +--+-+ +--+-+
| B0 | | B1 | | B3 | . . . . . | Bn | <- buffer
+-+--+ +-+--+ +-+--+ +-+--+ n is size-1
| | | |
+---+------+------+----------------+----+
| ACCUMULATOR |
+------------------+--------------------+
| <---------------------- sum
v
+--------+--------+
| divided by fill |
+--------+--------+
|
v
filtered
result

Code usage

/* Include library */#include"moving-average.h"/* Filter objects */movingAverage_tavg_filter;
movingAverage_tavg_filter_2;
voidmain()
{
/* Initialization of filters */moving_average_create(&avg_filter, 10, 100); /* filter size 10, sample time 100ms */moving_average_create(&avg_filter_2, 30, 150); /* filter size 30, sample time 150ms *//* wait for 1 maximum sample time */delay(150);
while(1)
{
signal=signal_source(); /* signal source function may ADC, Capture count, sensor data*//* Filter process *  * call this function maximum passible short time */moving_average_filter(&avg_filter, signal);
moving_average_filter(&avg_filter_2, signal);
process_or_print=avg_filter.filtered;
process_or_print=avg_filter_2.filtered;
}
}

Filter images

• channel 0 - signal + noise (+/- 20)
• channel 1 - filter size 10, sample time 100ms
• channel 2 - filter size 30, sample time 100ms
• channel 3 - filter size 50, sample time 100ms

Thank to Graph - serial plot tool