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flicker_meter_nano.ino
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flicker_meter_nano.ino
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/*
Flicker Meter
Arduino Nano
This device checks the quality of light sources, especcially LED lamps.
These lamps are often flickering, usually on the 100-120Hz frequency (doubled frequency of power grid).
Flickering is displayed with the row of 10 leds (Kingbright DC-10EWA). The number of blinking LEDs is proportional to the flicker rate.
Light sensor used: Avago APDS-9006-020
It's possible and even better to use APDS-9007, because of higher range. It needs some testing.
Leds connected to digital pins from 2 to 11
Sensor connected to pin A6
Button connected to pin 12.
Ask me if you need user manual
(C) 2017 Evgeny Mazovetskiy, Elena Mazovetskaya
*/
//During waiting state we constantly measure average light and show it on display
#define STATE_WAITING 1
//Measuring state is when we inside light flickering measurement process. It's not used actually anywhere outside
#define STATE_MEASURING 2
//In this state we show flicker percentage. The number of blinking LEDs is proportional to the flicker rate.
#define STATE_DISPLAY 3
#define BUTTON1 12
#define SENSOR_PIN 6
#define SERIAL_SWITCH_PIN 13
#define LOOP_DELAY 10
#define SAMPLE_COUNT 256
int leds[] = {2,3,4,5,6,7,8,9,10,11};
int state = STATE_WAITING;
int button_last_state = HIGH;
int flickering = 0; // 0 - 100
int leds_to_blink = 0; //number of blinking LEDs
int x[SAMPLE_COUNT];
int serial_on = 0;
// the setup function runs once when you press reset or power the board
void setup() {
// initialize digital pin LED_BUILTIN as an output.
pinMode(LED_BUILTIN, OUTPUT);
for(int i = 0; i<10; i++){
pinMode(leds[i], OUTPUT);
}
pinMode(BUTTON1, INPUT_PULLUP);
pinMode(SERIAL_SWITCH_PIN, INPUT_PULLUP);
analogReference(EXTERNAL);
if (digitalRead(SERIAL_SWITCH_PIN) == 0){
Serial.begin(9600);
serial_on = 1;
}
ledTest();
}
// the loop function runs over and over again forever
void loop() {
int light;
static int counter = 0;
processButton();
switch (state){
case STATE_WAITING:
light = measureAverageLight();
if (serial_on && ((counter % 20) == 0)){
Serial.print("light sensor = ");
Serial.println(light);
counter = 0;
}
showLight(light);
counter++;
break;
case STATE_DISPLAY:
showFlickering();
delay(LOOP_DELAY);
break;
default:
delay(LOOP_DELAY);
}
}
void ledTest(){
for (int i=0; i<10; i++) {
digitalWrite(leds[i], HIGH);
delay(70);
digitalWrite(leds[i], LOW);
}
ledsOn();
delay(150);
ledsOff();
}
void ledsOff(){
for (int i=0; i<10; i++) {
digitalWrite(leds[i], LOW);
}
}
void ledsOn(){
for (int i=0; i<10; i++) {
digitalWrite(leds[i], HIGH);
}
}
// This version requires additional button press to switch from flickering display to waiting mode
//
//void processButton(){
// int btn_state = digitalRead(BUTTON1);
//
// if ((btn_state == LOW) && (button_last_state == HIGH)){
// switch (state){
// case STATE_WAITING:
// flickering = measureFlickering();
// calcLEDsToBlink(flickering);
// state = STATE_DISPLAY;
// break;
// case STATE_DISPLAY:
// state = STATE_WAITING;
// break;
// }
// }
//
//
//
// button_last_state = btn_state;
//}
/**
* this version displays flickering while button is pressed. When bottun released, the state switches to waiting mode
*/
void processButton(){
int btn_state = digitalRead(BUTTON1);
if ((btn_state == LOW) && (button_last_state == HIGH)){
flickering = measureFlickering();
calcLEDsToBlink(flickering);
state = STATE_DISPLAY;
} else if ((btn_state == LOW) && (state == STATE_DISPLAY)) {
//do nothing, continue doing STATE_DISPLAY
} else if (btn_state == HIGH && (state != STATE_WAITING)){
//button released, we should be in waiting mode
state = STATE_WAITING;
}
button_last_state = btn_state;
}
void calcLEDsToBlink(int flickering){
leds_to_blink = 0;
if (flickering <= 5){
return;
}
leds_to_blink = ((flickering-1) - (flickering-1)%10) / 10 + 1;
return;
}
// /*
// *
// * Version for Avago APDS-9007 sensor with 27k load resistor
// * It did not work actually, because 27k is too much for ATMEGA328 ADC. To avoid noise, it should be less that 10k. I did not test APDS-9007 with lower loads yet
// *
// * return flickering percentage 0 - 100%
// */
//int measureFlickering(){
// float x_min = 1024,
// x_max = 0;
//
// ledsOff();
// noInterrupts();
// for (int i = 0; i < SAMPLE_COUNT; i++){
// x[i] = analogRead(SENSOR_PIN);
// x_min = min(x_min, x[i]);
// x_max = max(x_max, x[i]);
// delay(1);
// }
// interrupts();
//
// serialPrintX();
//
// //exp(0.006674178041 * (adc / 1.06667)); this is a magic formula of Lux for 12bit ADC with 3.3V max. It's not 100% accurate, because I don't have industrial Luxmeter, but it doesn't metter for flickering
//
// //convert to the magic-formula scale
// x_min = 6.06 * x_min;
// x_max = 6.06 * x_max;
//
// //convert to Lux
// x_min = pow(2.7182818285, 0.006674178041127581 * (x_min / 1.06667));
// x_max = pow(2.7182818285, 0.006674178041127581 * (x_max / 1.06667));
//
// return int((x_max - x_min) / x_max *100);
//}
/*
* return flickering percentage 0 - 100%
*/
//
// Version for Avago APDS-9006-020 sensor with 1.8k load resistor
//
// return flickering percentage 0 - 100%
//
int measureFlickering(){
float x_min = 1024,
x_max = 0;
ledsOff();
noInterrupts();
for (int i = 0; i < SAMPLE_COUNT; i++){
x[i] = analogRead(SENSOR_PIN);
x_min = min(x_min, x[i]);
x_max = max(x_max, x[i]);
delay(1);
}
interrupts();
if (serial_on){
serialPrintX();
}
return int((x_max - x_min) / x_max *100);
}
/**
* APDS-9006-020 is slow. It can not really measure > than 150Hz.
*/
int measureAverageLight(){
int result = 0;
for (int i = 1; i <= 10; i++){
result += analogRead(SENSOR_PIN);
delay(5);
}
return result / 10;
}
void serialPrintX(){
for (int i = 0; i < SAMPLE_COUNT; i++){
Serial.println(x[i]);
}
}
void showLight(int light){
//Number of leds to turn on
light = (light - light % 70) / 70;
for (int i = 0; i < 10; i++){
digitalWrite(leds[9-i], (i < light) );
}
}
void showFlickering(){
static int counter = 0;
static int blink_state = 1;
counter++;
if (counter > (300 / LOOP_DELAY)){
counter = 0;
blink_state = blink_state ^ 1;
}
for (int i = 1; i <= 10; i++){
if (i <= leds_to_blink){
digitalWrite(leds[i-1], blink_state);
} else {
digitalWrite(leds[i-1], HIGH);
}
}
}