Arduino can provide time related functions like in milli and micro seconds . However it can’t provide the real time (year, month, hour, minute and seconds). To obtain that information we will use different kinds of electronic components like RTC (Real Time Clock)and LCD display in order to get it in visual form.
Objectives #
- Know how we can use RTC ( Real Time Clock) in order to provide a precise time clock.
- To display that information on an LCD screen.
Component to Use #
- MPK kit A
- RTC ( Real Time Clock )
- LCD display ( with I2C module )
- Jumper wires
- Breadboard
- Microcontroller
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Circuit Diagram #
NOTE: Refer to Project 16 for LCD display connection.
Figure: Components used to make connection on the board
Arduino codes #
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#include<Wire.h>
#includeLiquidCrystal.h> // For the LCD
LiquidCrystallcd(7,8,9,10,11,12); // Pins for RS, E, D4, D5, D6, D7
#defineDS3231_I2C_ADDRESS 104 // RTC is connected, address is Hex68 (Decimal 104)
// SCL – pin A5
// SDA – pin A4
// To set the clock, run the sketch and use the serial monitor.
// Enter T1124154091014; the code will read this and set the clock. See the code for full details.
//
byte seconds, minutes, hours, day, date, month, year;
char weekDay[4];
byte tMSB, tLSB;
float my_temp;
char my_array[100]; // Character array for printing something.
void setup(){
Wire.begin();
Serial.begin(9600);
lcd.begin(16,2); // initialize the lcd (16 columns, 2 rows)
}
voidloop()
watchConsole();
get3231Date();
Serial.print(weekDay);
Serial.print(“,”);
Serial.print(date,DEC);
Serial.print(“/”);
Serial.print(month,DEC);
Serial.print(“/”);
Serial.print(year,DEC);
Serial.print(“-“);
Serial.print(hours,DEC);
Serial.print(“:”);
Serial.print(minutes,DEC);
Serial.print(“:”);
Serial.print(seconds,DEC);
my_temp = (float)get3231Temp();
Serial.print(” – Temp: “);
Serial.print(my_temp);
// NOTE: Arduino does NOT implement printing floats to a string.// If you use the std C function : sprintf(my_array, “Temp: %4.2f”, my_temp), It will NOT CONVERT.
// So I abandoned this, since I don’t need to print the float to the LCD anyway.
sprintf(my_array, “Time: %d:%d:%d”,minutes,hours, seconds, ;
// Print a message to the LCD.
lcd.setCursor(0,0);
lcd.print(weekDay);
lcd.print(“, “);
lcd.print(date,DEC)
lcd.print(“/”);
lcd.print(month,DEC)
lcd.print(“/”);
lcd.print(year,DEC)
lcd.(0,1);
lcd.print(my_array);
lcd.delay(1000);
}// Convert normal decimal numbers to binary coded decimal
byte decToBcd(byte val){
return( (val/10*16) + (val%10) );
}void watchConsole(){
if(Serial.available()) { // Look for char in serial queue and process if found
if(Serial.read() == 84) { //If command = “T” Set Date
set3231Date();
get3231Date();
Serial.println(” “);
}
}
}
voidset3231Date();
//T(sec)(min)(hour)(dayOfWeek)(dayOfMonth)(month)(year)
//T(00-59)(00-59)(00-23)(1-7)(01-31)(01-12)(00-99)
//Example: 02-Feb-09 @ 19:57:11 for the 3rd day of the week -> T1157193020209
// T1124154091014
Seconds = (byte) ((Serial.read() – 48) * 10 + (Serial.read() – 48)); // Use of (byte) type casting and ascii math to achieve the result.
minutes = (byte) ((Serial.read() – 48) * 10 + (Serial.read() – 48));
hours = (byte) ((Serial.read() – 48) * 10 + (Serial.read() – 48));
day = (byte) (Serial.read() – 48);
date= (byte) ((Serial.read() – 48) * 10 + (Serial.read() – 48));
month = (byte) (Serial.read() – 48);
year = (byte) (Serial.read() – 48);
Wire.beginTransmission(DS3231_I2C_ADDRESS);
Wire.write(0x00);
Wire.write(decToBcd(seconds));
Wire.write(decToBcd(minutes));
Wire.write(decToBcd(hours));
Wire.write(decToBcd(day));
Wire.write(decToBcd(date));
Wire.write(decToBcd(month));
Wire.write(decToBcd(year));
Wire.endTransmission();
}
void get3231Date()
{
// send request to receive data starting at register 0
Wire.beginTransmission(DS3231_I2C_ADDRESS); // 104 is DS3231 device address
Wire.write(0x00); // start at register 0
Wire.endTransmission
Wire.requestFrom(DS3231_I2C_ADDRESS, 7); // request seven bytes
if(Wire.available()) {
seconds = Wire.read(); // get seconds
minutes = Wire.read(); // get minutes
hours = Wire.read(); // get hours
day = Wire.read();
date = Wire.read();
month = Wire.read();//temp month
year = Wire.read();
seconds = (((seconds & B11110000)>>4)*10 + (seconds& B00001111)); // convert BCD to decimal
minutes = (((minutes & B11110000)>>4)*10 + (minutes& B00001111)); // convert BCD to decimal
hours = (((hours & B11110000)>>4)*10 + (hours& B00001111)); // convert BCD to decimal (assume 24 hour mode)
day = (day & B00000111); // 1-7
date = (((date & B00110000)>>4)*10 + (date & B00001111)); // 1-31
month = (((month & B11110000)>>4)*10 + (month & B00001111)); //msb7 is century overflow
year = (((year & B11110000)>>4)*10 + (year & B00001111));
}
else{
//oh noes, no data!
}
switch(day) {
case1
stropy(weekDay, “Sun”);
break;
case2
stropy(weekDay, “Mon”);
break;
case3
stropy(weekDay, “Tue”);
break;
case4
stropy(weekDay, “Wed”);
break;
case5
stropy(weekDay, “Thu”);
break;
case6
stropy(weekDay, “Fri”);
break;
case7
stropy(weekDay, “Sat”);
break;
}
}
floatget3231Temp()
{
float temp3231;
//temp registers (11h-12h) get updated automatically every 64s
Wire.beginTransmission(DS3231_I2C_ADDRESS);
Wire.write(0x11);
Wire.endTransmission();
Wire.requestFrom(DS3231_I2C_ADDRESS, 2);
if(Wire.available()) {
tMSB = Wire.read(); //2’s complement int portion
tMSB = Wire.read(); //fraction portion
temp3231 = (tMSB & B01111111); //do 2’s math on Tmsb
temp3231 += ( (tLSB >> 6) * 0.25 ); //only care about bits 7 & 8
}
else{
//oh noes, no data!
}
return temp3231;
}
Code knowledge #
This program involves displaying the date, time, and temperature on an LCD screen, using the DS3231 Real-Time Clock (RTC) and an LCD display. It also prints these details to the Serial Monitor.
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byte seconds, minutes, hours, day, date, month, year;
char weekDay[4];
byte tMSB, tLSB;
float my_temp;
char my_array[100]; // Character array for printing something.
- These variables hold values for time (hours, minutes, seconds), date (day, date, month, year), and temperature (my_temp).
- my_array is used to store a message to display on the LCD.
This code block is part of the loop() function in an Arduino program, and it continuously reads the time, date, and temperature from an RTC (Real-Time Clock) module and displays them on an LCD and the Serial Monitor. Here’s a breakdown of each part:
- Check for Console Commands
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watchConsole();
