Im trying to measure LED ON/OFF time using millis to display the time on LCD, the project idea is to use an IR sensor to detect motion, if there is motion then LED is on, otherwise it's off. I want to measure the time duration for on and off apart. But the timer keeps counting without resetting. how to make it reset? please help, thanks in advance<3.
this is my code:
#include <LiquidCrystal.h> // include the library code:
[code]
#include <LiquidCrystal.h> // include the library code:
int sensor_pin = 8; // Initialized the pin for motion sensor
int relay_pin = 9; // Initialized the pin for relay module
int output; // Variable to store the output state of motion sensor
LiquidCrystal lcd(12, 11, 5, 4, 3, 2); // initialize the library with the numbers of the interface pins
void setup(){
lcd.begin(16, 2); // set up the LCD's number of columns and rows
Serial.begin(9600);
pinMode(sensor_pin, INPUT); // Declared motion sensor pin as Input
pinMode(relay_pin, OUTPUT); // Declared relay module pin as Output pin
// Make the relay module initial state as low, Relay works opposite
pinMode(13, OUTPUT); //Set Pin13 as output
digitalWrite(13, HIGH);
digitalWrite(relay_pin, LOW);
// set the cursor to column 0, line 1
}
void loop(){
// Read the output state of motion sensor
output = digitalRead(sensor_pin);
// If output is High
if(output == 1){
digitalWrite(relay_pin, HIGH);
lcd.setCursor(0, 0);
lcd.print("LIGHT IS ONN"); // Print a message to the LCD.
// print the number of seconds since reset:
lcd.setCursor(0, 1);
// print the number of seconds since reset:
lcd.print( millis() / 1000);
}
// If output is LOW
else
{
digitalWrite(relay_pin, LOW);
lcd.setCursor(0, 0);
lcd.print("LIGHT IS OFF"); // Print a message to the LCD.
// print the number of seconds since reset:
lcd.setCursor(0, 1);
// print the number of seconds since reset:
lcd.print(millis() / 1000);
}
Serial.println(output);
delay(50);
}
Okayy i've modified my code to this, replaced lcd.print( millis() / 1000) to lcd.print( used_millis / 1000)
sorry but i might be doing something wrong, cuz im a beginner
#include <LiquidCrystal.h> // include the library code:
int sensor_pin = 8; // Initialized the pin for motion sensor
int relay_pin = 9; // Initialized the pin for relay module
int output; // Variable to store the output state of motion sensor
uint32_t mytimestamp = millis();
LiquidCrystal lcd(12, 11, 5, 4, 3, 2); // initialize the library with the numbers of the interface pins
void setup(){
lcd.begin(16, 2); // set up the LCD's number of columns and rows
Serial.begin(9600);
pinMode(sensor_pin, INPUT); // Declared motion sensor pin as Input
pinMode(relay_pin, OUTPUT); // Declared relay module pin as Output pin
// Make the relay module initial state as low, Relay works opposite
pinMode(13, OUTPUT); //Set Pin13 as output
digitalWrite(13, HIGH);
digitalWrite(relay_pin, LOW);
// set the cursor to column 0, line 1
}
void loop(){
// Read the output state of motion sensor
output = digitalRead(sensor_pin);
// If output is High
if(output == 1){
digitalWrite(relay_pin, HIGH);
lcd.setCursor(0, 0);
lcd.print("LIGHT IS ONN"); // Print a message to the LCD.
// print the number of seconds since reset:
uint32_t used_millis = millis() - mytimestamp;
lcd.setCursor(0, 1);
// print the number of seconds since reset:
lcd.print( used_millis / 1000);
}
// If output is LOW
else
{
digitalWrite(relay_pin, LOW);
lcd.setCursor(0, 0);
lcd.print("LIGHT IS OFF"); // Print a message to the LCD.
// print the number of seconds since reset:
uint32_t used_millis = millis() - mytimestamp;
lcd.setCursor(0, 1);
// print the number of seconds since reset:
lcd.print( used_millis / 1000);
}
Serial.println(output);
delay(50);
}
oke i did this, when the light goes on, the timer on lcd resets to zero but stop counting, and when the light goes off the timer doesnt reset and continue counting
#include <LiquidCrystal.h> // include the library code:
int sensor_pin = 8; // Initialized the pin for motion sensor
int relay_pin = 9; // Initialized the pin for relay module
int output; // Variable to store the output state of motion sensor
uint32_t mytimestamp = millis();
LiquidCrystal lcd(12, 11, 5, 4, 3, 2); // initialize the library with the numbers of the interface pins
void setup(){
lcd.begin(16, 2); // set up the LCD's number of columns and rows
Serial.begin(9600);
pinMode(sensor_pin, INPUT); // Declared motion sensor pin as Input
pinMode(relay_pin, OUTPUT); // Declared relay module pin as Output pin
// Make the relay module initial state as low, Relay works opposite
pinMode(13, OUTPUT); //Set Pin13 as output
digitalWrite(13, HIGH);
digitalWrite(relay_pin, LOW);
// set the cursor to column 0, line 1
}
void loop(){
// Read the output state of motion sensor
output = digitalRead(sensor_pin);
// If output is High
if(output == 1){
digitalWrite(relay_pin, HIGH);
lcd.setCursor(0, 0);
lcd.print("LIGHT IS ONN"); // Print a message to the LCD.
// print the number of seconds since reset:
mytimestamp = millis();
uint32_t used_millis = millis() - mytimestamp;
lcd.setCursor(0, 1);
// print the number of seconds since reset:
lcd.print( used_millis / 1000);
}
// If output is LOW
else
{
digitalWrite(relay_pin, LOW);
lcd.setCursor(0, 0);
lcd.print("LIGHT IS OFF"); // Print a message to the LCD.
// print the number of seconds since reset:
uint32_t used_millis = millis() - mytimestamp;
lcd.setCursor(0, 1);
// print the number of seconds since reset:
lcd.print( millis() / 1000);
}
Serial.println(output);
delay(50);
}
The value in used_millis will never be more than 2. It will almost always be 0.
What is the purpose of this?
You REALLY need to look at the state change detection example. You want to record, it seems to me, to record when the switch BECOMES pressed (or released or both), NOT when the switch IS pressed (or IS released).
