Last time I’ve built a simple real time clock and calendar using Arduino UNO board and DS3231 and now I’m going to add two alarm functions and temperature monitor to the previous project. Related topic URL is the one below:
Arduino and DS3231 real time clock
The DS3231 RTC has a built-in two alarm functions and a temperature sensor with a resolution of 0.25 and an accuracy of ±3°C which make this project more easier.
Hardware Required:
- Arduino UNO or compatible board —> ATmega328P datasheet
- DS3231 RTC board —> DS3231 datasheet
- 2004 LCD screen
- 3 x push button
- LED
- 10K ohm variable resistor (or potentiometer)
- 2 x 330 ohm resistor
- 3V coin cell battery
- Breadboard
- Jumper wires
The circuit:
Project circuit schematic diagram is shown below.
In this project I used the DS3231 board, this board basically contains the main chip which is the DS3231, two pull-up resistors (4.7K) of SCL, SDA and INT/SQW lines and coin cell battery holder. There is also 24C32 EEPROM and some other resistors (not used in this project).
The DS3231 board is supplied with 5V as the 2004 LCD, this 5V comes from the Arduino board, there are 3 data lined connected between this board and the Arduino, SCL line is connected to analog pin 5, SDA is connected to analog pin 4 and INT line is connected to digital pin 2 which is the external interrupt pin of the Arduino. The DS3231 interrupts the microcontroller when there is an alarm (alarm1 or alarm2).
In the circuit there are 3 push buttons: B1, B2 and B3. These buttons are used to set time, calendar and alarms. Time and calendar can be adjusted with B1 and B2, button B1 selects time or date parameter (time parameters: hours and minutes; calendar parameters: day of the week, date, month and year) and B2 increments the selected parameter. Buttons B3 and B2 adjust alarm1 and alarm2 parameters (hours, minutes and ON/OFF), button B3 selects the parameter and B2 increments the selected parameter.
Also, there is an LED connected to Arduino pin 12, this LED is used as an alarm indicator (alarm1 or alarm2), so if there is an alarm the DS3231 pulls down the INT pin which interrupts the microcontroller and the microcontroller turns the LED ON, here button B2 turns both the LED and the occurred alarm OFF.
Arduino Code:
The Arduino code below doesn’t use any library for the DS3231.
By reading the datasheet of the DS3231 RTC the code will be more easier!
Programming hints:
The DS3231 works with BCD format only (except the temperature) and to convert the BCD to decimal and vise versa I used the following commands (example for minute variable):
minute = (minute >> 4) * 10 + (minute & 0x0F); // Convert BCD to decimal
minute = ((minute / 10) << 4) + (minute % 10); // Convert decimal to BCD
Code functions:
void DS3231_read() : this function reads time and calendar data from the DS3231 (seconds, minutes, hours, day, date, month and year).
void DS3231_display() : displays time and calendar data, before displaying time and calendar data are converted from BCD format to decimal format. This function displays the calendar by calling a function named void calendar_display() .
void alarms_read_display() : basically this functions reads alarm1 and alarm2 minutes and hours. It also reads the DS3231 control register, status register and temperature registers (2 registers).
The other job of this function is to display alarms data (hours, minutes and status) and the temperature value. The alarm status are extracted from the control register.
byte edit(byte x, byte y, byte parameter) : I used this function to edit time, calendar and alarm parameters except the day. I used a variable named i to distinguish between the parameters:
i = 0, 1 : time hours and minutes respectively
i = 2, 3, 4: calendar date, month and year respectively
i = 5, 6: alarms hours and minutes respectively
i = 7: alarm status (ON or OFF)
After the edit of time/calendar/alarms the data have to be converted back to BCD format and written to the DS3231.
The Arduino turns the LED ON when it interrupted by the DS3231, the DS3231 sends the interrupt signal (pulls down the INT line) when there has been an alarm. Button B2 resets and turns OFF the alarm. If both alarms are active, button B2 will resets and turns OFF the occurred alarm only and keeps the other as it is. To do that we’ve to detect which alarm has been occurred which can be easily done by reading the status register of the DS3231 (A1IF and A2IF flag bits). Turning ON or OFF an alarm is done by writing to the control register (bits: INTCN, A1IE and A2IE). Always INTCN bit should be 1. I used the following line to write 1 to the INTCN bit and to turn OFF the occurred alarm:
Wire.write(4 | (!bit_test(status_reg, 0) & alarm1_status) | ((!bit_test(status_reg, 1) & alarm2_status) << 1));
alarm1_status and alarm2_status are boolean variables (can be true or false), for example if alarm1_status is 1 ==> alarm1 is ON and if alarm1_status is 0 ==> alarm1 is OFF. The same thing for alarm2.
The complete Arduino code is below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 | /* 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, "Sun / /20 "); break; case 2: strcpy(calendar, "Mon / /20 "); break; case 3: strcpy(calendar, "Tue / /20 "); break; case 4: strcpy(calendar, "Wed / /20 "); break; case 5: strcpy(calendar, "Thu / /20 "); break; case 6: strcpy(calendar, "Fri / /20 "); break; case 7: strcpy(calendar, "Sat / /20 "); break; default: strcpy(calendar, "Sat / /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 |
Small Video:
The video below shows a simple hardware circuit of the project.
This program is set to have 31 days every month. How should I fix it?
Hi SP, is there a need to use an interrupt? Can I connect the SQW from the RTC to a random digital pin (and adjust the code accordingly to set a flag)?
What to do for 12 hour format with AM/PM showing ?
Please support to use this code wih LCD 16×2
please help me i wnat to replace the led with a buzzer but i need a photograph and the code again so please send it to me because i m new
Anyone looking for schematics of this project built using proteus can get them via this link: https://github.com/onurjuzelle/Ardunio-Alarm-Clock/tree/master/Proteus%208
Is there a Proteus simulation file for this project, like the one shared with the: Arduino and DS3231 real time clock ?
Can send this program wih LCD 16×2 without calendar and second?
I’m working on smth similar but i cant find all of the parts for proteus. It is possible for you guys to share project document so i can work on the simulation? Also which software do you guys use ?
Can I set 13 alarms?
Hi, I have one task. Can you help me?
The task is as follows:
I need to include at a specific hour and minute PWM that unfolds from 0-100% in 20 minutes (smooth). Stay 100% of the time spent and then return to 0% again in 20 minutes (smooth). This should all be in line with the actual date and time. Can Alarm 2 turn off Alarm 1. I hope you help me. Now I’m learning to work with Adruino. It’s a little complicated for me, but I hope it won’t be a problem for you.
thanks
Hi, can you help me? what mistake I’ve made, the led alarm is on, the button and the LCD are working properly.
I use pin 8 for the led alarm, I have adjusted the coding.
can I use the same code to ds1307?
No you can’t because the DS1307 doesn’t have hardware alarm functions and also the built-in temperature monitor.
I do not understand directly, because there are 2 temperatures (temperature_lsb; temperature_msb) do they do some type of media? Could you explain more?
If you can help me with some modifications the program would be very grateful!
My relay cannot on when set alarm on , why ? please help me
can I change the first alarm to be the start time and the second one to be the stop time if I want to use it to oparit fan that work with relay
Yes you can do that but you’ve to make some modifications.
How should we make changes? ::: 🙂
i did follow exactly but i cant get the lcd to display the words
hi i want to alarm evry 8am 12 noon, 1pm and 5 pm…i want to use it i hour school
hi. what about if i wanna make an alarm once a day in a week? example like i just want to set on the alarm on monday, 6 p.m. could you tell me how to make it?
Can you provide me alarm status and how I should stop alarm1 if another alarm2 match with time.. using ds3231 data sheet..
hey instead of led i wanted to add buzzer can you help me ? i am new to this so please would be big help
Yes you can add it. Buzzer works with PWM signal which means you’ve to replace digitalWrite(alarm_pin, HIGH); (located inside void Alarm) with your PWM code. Do the same thing to switch the buzzer off.
Generally buzzers work with a specified frequency (can be found in buzzer datasheet), configure your Arduino to generate a PWM signal appropriate to your buzzer.
Bonsoir, par hasard j’ai trouvé ce code formidable, je l’ai un peu modifier pour mon usage, supprimer une alarme et séparer la date du jour, avec un lcd 16×4, voici le code.
/* 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.
http://simple-circuit.com/arduino-ds3231-real-time-clock-alarm-temperature/
*/
// include LCD library code
#include
// include Wire library code (needed for I2C protocol devices)
#include
// LCD module connections (RS, E, D4, D5, D6, D7)
LiquidCrystal lcd(8,9,10,11,12,13);//pins(rs, enable, d4, d5, d6, d7)
const int button1 = 4; // bouton mise a l’heure,jour,date
const int button2 = 5; // stop alarme
const int button3 = 6; // bouton mise a l’heure alarme
const int alarm_pin = 7; // Alarme pin numero
void setup() {
pinMode(4, INPUT_PULLUP);
pinMode(5, INPUT_PULLUP);
pinMode(6, INPUT_PULLUP);
pinMode(7, OUTPUT);
digitalWrite(alarm_pin, LOW);
lcd.begin(16, 4);
Wire.begin();
attachInterrupt(digitalPinToInterrupt(2), Alarm, FALLING); //sortie SQW du DS 3231
}
// Variables declaration
bool alarm1_status, alarm2_status;
char Time[] = ” : : “,
calendar[] = ” “,
calend[] = ” / /20 “,
alarm1[] = “Al: : :00”;
byte i, second, minute, hour, day, date, month, year,
alarm1_minute, alarm1_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;
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
// 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
// Convert BCD to decimal
alarm1_minute = (alarm1_minute >> 4) * 10 + (alarm1_minute & 0x0F);
alarm1_hour = (alarm1_hour >> 4) * 10 + (alarm1_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;
alarm1_status = bitRead(control_reg, 0); // Read alarm1 interrupt enable bit (A1IE) from DS3231 control register
// Read alarm2 interrupt enable bit (A2IE) from DS3231 control register
lcd.setCursor(0, 3);
lcd.print(alarm1); // Display alarm1
lcd.setCursor(13, 3);
if(alarm1_status) lcd.print(“ON “); // If A1IE = 1 print ‘ON’
else lcd.print(“OFF”); // If A1IE = 0 print ‘OFF’
}
void calendar_display(){ // Function to display calendar
switch(day){
case 1: strcpy(calendar, “Dimanche “); break;
case 2: strcpy(calendar, “Lundi “); break;
case 3: strcpy(calendar, “Mardi “); break;
case 4: strcpy(calendar, “Mercredi “); break;
case 5: strcpy(calendar, “Jeudi “); break;
case 6: strcpy(calendar, “Vendredi “); break;
case 7: strcpy(calendar, “Samedi “); break;
default: strcpy(calendar, “Samedi “);
}
lcd.setCursor(0, 1);
lcd.print(calendar); // Display calendar
}
void calend_display(){
calend[13] = year % 10 + 48;
calend[12] = year / 10 + 48;
calend[8] = month % 10 + 48;
calend[7] = month / 10 + 48;
calend[5] = date % 10 + 48;
calend[4] = date / 10 + 48;
lcd.setCursor(0, 2);
lcd.print(calend); // 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
calend_display();
lcd.setCursor(4, 0);
lcd.print(Time); // Display time
}
void Blink(){
byte j = 0;
while(j = 5) && digitalRead(button2) && (digitalRead(button3) || i 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)){
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(4, 0, hour);
minute = edit(7, 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
calend_display();
lcd.setCursor(0, 1);
lcd.print(calendar); // Display calendar
lcd.setCursor(0, 2);
lcd.print(calend);
delay(200);
}
lcd.setCursor(0, 1);
lcd.print(” “); // Print 3 spaces
lcd.setCursor(0, 2);
lcd.print(” “);
Blink();
lcd.setCursor(0, 1);
lcd.print(calendar); // Print calendar
lcd.setCursor(0, 2);
lcd.print(calend);
Blink(); // Call Blink function
if(!digitalRead(button1)) // If button B1 is pressed
break;
}
date = edit(4, 2, date); // Edit date
month = edit(7, 2, month); // Edit month
year = edit(12, 2, 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, 3, alarm1_hour);
alarm1_minute = edit(7, 3, alarm1_minute);
alarm1_status = edit(13, 3, alarm1_status);
i = 5;
alarm1_minute = ((alarm1_minute / 10) << 4) + (alarm1_minute % 10);
alarm1_hour = ((alarm1_hour / 10) << 4) + (alarm1_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
// 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) ) << 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
}
hello greetings, nice to see your project, I want to ask you if it is possible to configure your skech to have as alarm days instead of hours
Yes, you can add day or date to the alarm functions, so the alarm will be when date, hours, and minutes match or when day, hours, and minutes match (hours can not be removed). To do that you’ve to do some modifications to the code. More details are on the DS3231 datasheet.