/* Arduino real time clock and calendar with 2 alarm functions and temperature monitor using DS3231
Read DS3231 RTC datasheet to understand the code
Time & date parameters can be set using two push buttons connected to pins 9 (B1) & 10 (B2).
Alarm1 and alarm2 can be set using two push buttons connected to 11 (B3) & 10 (B2).
Pin 12 becomes high when alarm occurred and button B2 returns it to low and
turns the occurred alarm OFF.
DS3231 interrupt pin is connected to Arduino external interrupt pin 2.
*/
// include LCD library code
#include <LiquidCrystal.h>
// include Wire library code (needed for I2C protocol devices)
#include <Wire.h>
// LCD module connections (RS, E, D4, D5, D6, D7)
LiquidCrystal lcd(3, 4, 5, 6, 7, 8);
const int button1 = 9; // button1 pin number
const int button2 = 10; // button1 pin number
const int button3 = 11; // button1 pin number
const int alarm_pin = 12; // Alarms pin number
void setup() {
pinMode(9, INPUT_PULLUP);
pinMode(10, INPUT_PULLUP);
pinMode(11, INPUT_PULLUP);
pinMode(12, OUTPUT);
digitalWrite(alarm_pin, LOW);
// set up the LCD's number of columns and rows
lcd.begin(20, 4);
Wire.begin(); // Join i2c bus
attachInterrupt(digitalPinToInterrupt(2), Alarm, FALLING);
}
// Variables declaration
bool alarm1_status, alarm2_status;
char Time[] = " : : ",
calendar[] = " / /20 ",
alarm1[] = "A1: : :00", alarm2[] = "A2: : :00",
temperature[] = "T: . C";
byte i, second, minute, hour, day, date, month, year,
alarm1_minute, alarm1_hour, alarm2_minute, alarm2_hour,
status_reg;
void Alarm(){
digitalWrite(alarm_pin, HIGH);
}
void DS3231_read(){ // Function to read time & calendar data
Wire.beginTransmission(0x68); // Start I2C protocol with DS3231 address
Wire.write(0); // Send register address
Wire.endTransmission(false); // I2C restart
Wire.requestFrom(0x68, 7); // Request 7 bytes from DS3231 and release I2C bus at end of reading
second = Wire.read(); // Read seconds from register 0
minute = Wire.read(); // Read minuts from register 1
hour = Wire.read(); // Read hour from register 2
day = Wire.read(); // Read day from register 3
date = Wire.read(); // Read date from register 4
month = Wire.read(); // Read month from register 5
year = Wire.read(); // Read year from register 6
}
void alarms_read_display(){ // Function to read and display alarm1, alarm2 and temperature data
byte control_reg, temperature_lsb;
char temperature_msb;
Wire.beginTransmission(0x68); // Start I2C protocol with DS3231 address
Wire.write(0x08); // Send register address
Wire.endTransmission(false); // I2C restart
Wire.requestFrom(0x68, 11); // Request 11 bytes from DS3231 and release I2C bus at end of reading
alarm1_minute = Wire.read(); // Read alarm1 minutes
alarm1_hour = Wire.read(); // Read alarm1 hours
Wire.read(); // Skip alarm1 day/date register
alarm2_minute = Wire.read(); // Read alarm2 minutes
alarm2_hour = Wire.read(); // Read alarm2 hours
Wire.read(); // Skip alarm2 day/date register
control_reg = Wire.read(); // Read the DS3231 control register
status_reg = Wire.read(); // Read the DS3231 status register
Wire.read(); // Skip aging offset register
temperature_msb = Wire.read(); // Read temperature MSB
temperature_lsb = Wire.read(); // Read temperature LSB
// Convert BCD to decimal
alarm1_minute = (alarm1_minute >> 4) * 10 + (alarm1_minute & 0x0F);
alarm1_hour = (alarm1_hour >> 4) * 10 + (alarm1_hour & 0x0F);
alarm2_minute = (alarm2_minute >> 4) * 10 + (alarm2_minute & 0x0F);
alarm2_hour = (alarm2_hour >> 4) * 10 + (alarm2_hour & 0x0F);
// End conversion
alarm1[8] = alarm1_minute % 10 + 48;
alarm1[7] = alarm1_minute / 10 + 48;
alarm1[5] = alarm1_hour % 10 + 48;
alarm1[4] = alarm1_hour / 10 + 48;
alarm2[8] = alarm2_minute % 10 + 48;
alarm2[7] = alarm2_minute / 10 + 48;
alarm2[5] = alarm2_hour % 10 + 48;
alarm2[4] = alarm2_hour / 10 + 48;
alarm1_status = bitRead(control_reg, 0); // Read alarm1 interrupt enable bit (A1IE) from DS3231 control register
alarm2_status = bitRead(control_reg, 1); // Read alarm2 interrupt enable bit (A2IE) from DS3231 control register
if(temperature_msb < 0){
temperature_msb = abs(temperature_msb);
temperature[2] = '-';
}
else
temperature[2] = ' ';
temperature_lsb >>= 6;
temperature[4] = temperature_msb % 10 + 48;
temperature[3] = temperature_msb / 10 + 48;
if(temperature_lsb == 0 || temperature_lsb == 2){
temperature[7] = '0';
if(temperature_lsb == 0) temperature[6] = '0';
else temperature[6] = '5';
}
if(temperature_lsb == 1 || temperature_lsb == 3){
temperature[7] = '5';
if(temperature_lsb == 1) temperature[6] = '2';
else temperature[6] = '7';
}
temperature[8] = 223; // Put the degree symbol
lcd.setCursor(10, 0);
lcd.print(temperature); // Display temperature
lcd.setCursor(0, 2);
lcd.print(alarm1); // Display alarm1
lcd.setCursor(17, 2);
if(alarm1_status) lcd.print("ON "); // If A1IE = 1 print 'ON'
else lcd.print("OFF"); // If A1IE = 0 print 'OFF'
lcd.setCursor(0, 3);
lcd.print(alarm2); // Display alarm2
lcd.setCursor(17, 3);
if(alarm2_status) lcd.print("ON "); // If A2IE = 1 print 'ON'
else lcd.print("OFF"); // If A2IE = 0 print 'OFF'
}
void calendar_display(){ // Function to display calendar
switch(day){
case 1: strcpy(calendar, "DOM / /20 "); break;
case 2: strcpy(calendar, "LUN / /20 "); break;
case 3: strcpy(calendar, "MAR / /20 "); break;
case 4: strcpy(calendar, "MIR / /20 "); break;
case 5: strcpy(calendar, "JUE / /20 "); break;
case 6: strcpy(calendar, "VIE / /20 "); break;
case 7: strcpy(calendar, "SAB / /20 "); break;
default: strcpy(calendar, "LUN / /20 ");
}
calendar[13] = year % 10 + 48;
calendar[12] = year / 10 + 48;
calendar[8] = month % 10 + 48;
calendar[7] = month / 10 + 48;
calendar[5] = date % 10 + 48;
calendar[4] = date / 10 + 48;
lcd.setCursor(0, 1);
lcd.print(calendar); // Display calendar
}
void DS3231_display(){
// Convert BCD to decimal
second = (second >> 4) * 10 + (second & 0x0F);
minute = (minute >> 4) * 10 + (minute & 0x0F);
hour = (hour >> 4) * 10 + (hour & 0x0F);
date = (date >> 4) * 10 + (date & 0x0F);
month = (month >> 4) * 10 + (month & 0x0F);
year = (year >> 4) * 10 + (year & 0x0F);
// End conversion
Time[7] = second % 10 + 48;
Time[6] = second / 10 + 48;
Time[4] = minute % 10 + 48;
Time[3] = minute / 10 + 48;
Time[1] = hour % 10 + 48;
Time[0] = hour / 10 + 48;
calendar_display(); // Call calendar display function
lcd.setCursor(0, 0);
lcd.print(Time); // Display time
}
void Blink(){
byte j = 0;
while(j < 10 && (digitalRead(button1) || i >= 5) && digitalRead(button2) && (digitalRead(button3) || i < 5)){
j++;
delay(25);
}
}
byte edit(byte x, byte y, byte parameter){
char text[3];
while(!digitalRead(button1) || !digitalRead(button3)); // Wait until button B1 is released
while(true){
while(!digitalRead(button2)){ // If button B2 is pressed
parameter++;
if(((i == 0) || (i == 5)) && parameter > 23) // If hours > 23 ==> hours = 0
parameter = 0;
if(((i == 1) || (i == 6)) && parameter > 59) // If minutes > 59 ==> minutes = 0
parameter = 0;
if(i == 2 && parameter > 31) // If date > 31 ==> date = 1
parameter = 1;
if(i == 3 && parameter > 12) // If month > 12 ==> month = 1
parameter = 1;
if(i == 4 && parameter > 99) // If year > 99 ==> year = 0
parameter = 0;
if(i == 7 && parameter > 1) // For alarms ON or OFF (1: alarm ON, 0: alarm OFF)
parameter = 0;
lcd.setCursor(x, y);
if(i == 7){ // For alarms ON & OFF
if(parameter == 1) lcd.print("ON ");
else lcd.print("OFF");
}
else{
sprintf(text,"%02u", parameter);
lcd.print(text);
}
if(i >= 5){
DS3231_read(); // Read data from DS3231
DS3231_display(); // Display DS3231 time and calendar
}
delay(200); // Wait 200ms
}
lcd.setCursor(x, y);
lcd.print(" "); // Print two spaces
if(i == 7) lcd.print(" "); // Print space (for alarms ON & OFF)
Blink(); // Call Blink function
lcd.setCursor(x, y);
if(i == 7){ // For alarms ON & OFF
if(parameter == 1) lcd.print("ON ");
else lcd.print("OFF");
}
else{
sprintf(text,"%02u", parameter);
lcd.print(text);
}
Blink();
if(i >= 5){
DS3231_read();
DS3231_display();}
if((!digitalRead(button1) && i < 5) || (!digitalRead(button3) && i >= 5)){
i++; // Increment 'i' for the next parameter
return parameter; // Return parameter value and exit
}
}
}
void loop() {
if(!digitalRead(button1)){ // If B1 button is pressed
i = 0;
hour = edit(0, 0, hour);
minute = edit(3, 0, minute);
while(!digitalRead(button1)); // Wait until button B1 released
while(true){
while(!digitalRead(button2)){ // If button B2 button is pressed
day++; // Increment day
if(day > 7) day = 1;
calendar_display(); // Call display_calendar function
lcd.setCursor(0, 1);
lcd.print(calendar); // Display calendar
delay(200);
}
lcd.setCursor(0, 1);
lcd.print(" "); // Print 3 spaces
Blink();
lcd.setCursor(0, 1);
lcd.print(calendar); // Print calendar
Blink(); // Call Blink function
if(!digitalRead(button1)) // If button B1 is pressed
break;
}
date = edit(4, 1, date); // Edit date
month = edit(7, 1, month); // Edit month
year = edit(12, 1, year); // Edit year
// Convert decimal to BCD
minute = ((minute / 10) << 4) + (minute % 10);
hour = ((hour / 10) << 4) + (hour % 10);
date = ((date / 10) << 4) + (date % 10);
month = ((month / 10) << 4) + (month % 10);
year = ((year / 10) << 4) + (year % 10);
// End conversion
// Write time & calendar data to DS3231 RTC
Wire.beginTransmission(0x68); // Start I2C protocol with DS3231 address
Wire.write(0); // Send register address
Wire.write(0); // Reset sesonds and start oscillator
Wire.write(minute); // Write minute
Wire.write(hour); // Write hour
Wire.write(day); // Write day
Wire.write(date); // Write date
Wire.write(month); // Write month
Wire.write(year); // Write year
Wire.endTransmission(); // Stop transmission and release the I2C bus
delay(200);
}
if(!digitalRead(button3)){ // If B3 button is pressed
while(!digitalRead(button3)); // Wait until button B3 released
i = 5;
alarm1_hour = edit(4, 2, alarm1_hour);
alarm1_minute = edit(7, 2, alarm1_minute);
alarm1_status = edit(17, 2, alarm1_status);
i = 5;
alarm2_hour = edit(4, 3, alarm2_hour);
alarm2_minute = edit(7, 3, alarm2_minute);
alarm2_status = edit(17, 3, alarm2_status);
alarm1_minute = ((alarm1_minute / 10) << 4) + (alarm1_minute % 10);
alarm1_hour = ((alarm1_hour / 10) << 4) + (alarm1_hour % 10);
alarm2_minute = ((alarm2_minute / 10) << 4) + (alarm2_minute % 10);
alarm2_hour = ((alarm2_hour / 10) << 4) + (alarm2_hour % 10);
// Write alarms data to DS3231
Wire.beginTransmission(0x68); // Start I2C protocol with DS3231 address
Wire.write(7); // Send register address (alarm1 seconds)
Wire.write(0); // Write 0 to alarm1 seconds
Wire.write(alarm1_minute); // Write alarm1 minutes value to DS3231
Wire.write(alarm1_hour); // Write alarm1 hours value to DS3231
Wire.write(0x80); // Alarm1 when hours, minutes, and seconds match
Wire.write(alarm2_minute); // Write alarm2 minutes value to DS3231
Wire.write(alarm2_hour); // Write alarm2 hours value to DS3231
Wire.write(0x80); // Alarm2 when hours and minutes match
Wire.write(4 | alarm1_status | (alarm2_status << 1)); // Write data to DS3231 control register (enable interrupt when alarm)
Wire.write(0); // Clear alarm flag bits
Wire.endTransmission(); // Stop transmission and release the I2C bus
delay(200); // Wait 200ms
}
if(!digitalRead(button2) && digitalRead(alarm_pin)){ // When button B2 pressed with alarm (Reset and turn OFF the alarm)
digitalWrite(alarm_pin, LOW); // Turn OFF the alarm indicator
Wire.beginTransmission(0x68); // Start I2C protocol with DS3231 address
Wire.write(0x0E); // Send register address (control register)
// Write data to control register (Turn OFF the occurred alarm and keep the other as it is)
Wire.write(4 | (!bitRead(status_reg, 0) & alarm1_status) | ((!bitRead(status_reg, 1) & alarm2_status) << 1));
Wire.write(0); // Clear alarm flag bits
Wire.endTransmission(); // Stop transmission and release the I2C bus
}
DS3231_read(); // Read time and calendar parameters from DS3231 RTC
alarms_read_display(); // Read and display alarms parameters
DS3231_display(); // Display time & calendar
delay(50); // Wait 50ms
}
// End of code