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Code Issues Releases Wiki Activity

Low pass filter added

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This commit is contained in:
Martin Kompf 2019-02-09 19:05:53 +01:00
parent 2f638128fa
commit 7eede54912
1 changed files with 39 additions and 9 deletions
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48
arduino_sketch/ReflectorLightBarrier.ino
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@ -5,7 +5,7 @@
* and communicates with a master computer (Raspberry Pi)
* over USB serial.
* Copyright 2015 Martin Kompf
* Copyright 2015-19 Martin Kompf
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
@ -29,6 +29,14 @@ const int ledOutPin = 12; // Signal LED output pin
int sensorValueOff = 0; // value read from the photo transistor when ir LED is off
int sensorValueOn = 0; // value read from the photo transistor when ir LED is on
int sensorValue = 0; // difference sensorValueOn - sensorValueOff
float filteredValue; // filtered sensor value
// definitions for low pass filter
#define FILTER_LEN 6
float buffer[FILTER_LEN];
int startBuf = 0;
int lenBuf = 0;
// command line
#define MAX_CMD_LEN 80
@ -47,8 +55,8 @@ char mode = 'D';
char dataOutput = 'T';
// trigger state and level
int triggerLevelLow;
int triggerLevelHigh;
float triggerLevelLow;
float triggerLevelHigh;
boolean triggerState = false;
// Address of trigger levels in EEPROM
@ -87,8 +95,8 @@ void setTriggerLevels() {
* Read trigger levels from EEPROM
*/
void readTriggerLevels() {
triggerLevelLow = (int)eeprom_read_word(&triggerLevelLowAddr);
triggerLevelHigh = (int)eeprom_read_word(&triggerLevelHighAddr);
triggerLevelLow = (float)eeprom_read_word(&triggerLevelLowAddr);
triggerLevelHigh = (float)eeprom_read_word(&triggerLevelHighAddr);
Serial.print("Trigger levels: ");
Serial.print(triggerLevelLow);
Serial.print(" ");
@ -98,7 +106,7 @@ void readTriggerLevels() {
/**
* Detect and print a trigger event
*/
void detectTrigger(int val) {
void detectTrigger(float val) {
boolean nextState = triggerState;
if (val > triggerLevelHigh) {
nextState = true;
@ -163,6 +171,24 @@ void doCommand() {
cmdComplete = false;
}
/*
* Low pass filter to eleminate spikes
*/
float lowpass(int value) {
if (lenBuf < FILTER_LEN) {
lenBuf++;
}
buffer[startBuf++] = (float) value;
if (startBuf >= FILTER_LEN) {
startBuf = 0;
}
float sum = 0;
for (int i = 0; i < lenBuf; ++i) {
sum += buffer[i];
}
return sum / lenBuf;
}
/**
* Setup.
*/
@ -203,16 +229,20 @@ void loop() {
digitalWrite(irOutPin, HIGH);
delay(10);
// read the analog in value:
sensorValueOn = analogRead(analogInPin);
sensorValueOn = analogRead(analogInPin);
sensorValue = sensorValueOn - sensorValueOff;
filteredValue = lowpass(sensorValue);
switch (dataOutput) {
case 'R':
// print the raw data to the serial monitor
Serial.println(sensorValueOn - sensorValueOff);
Serial.print(sensorValue);
Serial.print(' ');
Serial.println(filteredValue, 3);
break;
case 'T':
// detect and output trigger
detectTrigger(sensorValueOn - sensorValueOff);
detectTrigger(filteredValue);
break;
}
}