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I am trying to set the time and date of my real time clock, but it is having a problem reading the data I type in to the serial monitor. In the code below, it asks if I want to change the date, and I type "y" and press enter. After that, it asks for the year, and I type"14" and press enter, but nothing happens.

#include <Wire.h>
const int DS1307 = 0x68; // Address of DS1307 see data sheets
const char* days[] =
{"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};
const char* months[] =
{"January", "February", "March", "April", "May", "June", "July", "August","September", "October", "November", "December"};

// Initializes all values: 
byte second = 0;
byte minute = 0;
byte hour = 0;
byte weekday = 0;
byte monthday = 0;
byte month = 0;
byte year = 0;

void setup() {
  Wire.begin();
  Serial.begin(9600);
  delay(2000); // This delay allows the MCU to read the current date and time.

  Serial.print("The current date and time is: ");
  printTime();
  Serial.println("Please change to newline ending the settings on the lower right of the Serial Monitor");
  Serial.println("Would you like to set the date and time now? Y/N");

  while (!Serial.available()) delay(10);
  if (Serial.read() == 'y' || Serial.read() == 'Y')

  // This set of functions allows the user to change the date and time
  {
    Serial.read();
    setTime();
    Serial.print("The current date and time is now: ");
    printTime();
  }


  Serial.println("Thank you.");
}

// Continuous function for converting bytes to decimals and vice versa
void loop() {
}
byte decToBcd(byte val) {
  return ((val/10*16) + (val%10));
}
byte bcdToDec(byte val) {
  return ((val/16*10) + (val%16));
}


// This set of codes is allows input of data
void setTime() {
  Serial.print("Please enter the current year, 00-99. - ");
  year = readByte();
  Serial.println(year);
  Serial.print("Please enter the current month, 1-12. - ");
  month = readByte();
  Serial.println(months[month-1]);
  Serial.print("Please enter the current day of the month, 1-31. - ");
  monthday = readByte();
  Serial.println(monthday);
  Serial.println("Please enter the current day of the week, 1-7.");
  Serial.print("1 Sun | 2 Mon | 3 Tues | 4 Weds | 5 Thu | 6 Fri | 7 Sat - ");
  weekday = readByte();
  Serial.println(days[weekday-1]);
  Serial.print("Please enter the current hour in 24hr format, 0-23. - ");
  hour = readByte();
  Serial.println(hour);
  Serial.print("Please enter the current minute, 0-59. - ");
  minute = readByte();
  Serial.println(minute);
  second = 0;
  Serial.println("The data has been entered.");

  // The following codes transmits the data to the RTC
  Wire.beginTransmission(DS1307);
  Wire.write(byte(0));
  Wire.write(decToBcd(second));
  Wire.write(decToBcd(minute));
  Wire.write(decToBcd(hour));
  Wire.write(decToBcd(weekday));
  Wire.write(decToBcd(monthday));
  Wire.write(decToBcd(month));
  Wire.write(decToBcd(year));
  Wire.write(byte(0));
  Wire.endTransmission();
  // Ends transmission of data
}


byte readByte() {
  while (!Serial.available()) delay(10);
  byte reading = 0;
  byte incomingByte = Serial.read();
  while (incomingByte != '\n') {
    if (incomingByte >= '0' && incomingByte <= '9')
      reading = reading * 10 + (incomingByte - '0');
    else;
    incomingByte = Serial.read();
  }
  Serial.flush();
  return reading;
}


void printTime() {
  char buffer[3];
  const char* AMPM = 0;
  readTime();
  Serial.print(days[weekday-1]);
  Serial.print(" ");
  Serial.print(months[month-1]);
  Serial.print(" ");
  Serial.print(monthday);
  Serial.print(", 20");
  Serial.print(year);
  Serial.print(" ");
  if (hour > 12) {
    hour -= 12;
    AMPM = " PM";
  }
  else AMPM = " AM";
  Serial.print(hour);
  Serial.print(":");
  sprintf(buffer, "%02d", minute);
  Serial.print(buffer);
  Serial.println(AMPM);
}


void readTime() {
  Wire.beginTransmission(DS1307);
  Wire.write(byte(0));
  Wire.endTransmission();
  Wire.requestFrom(DS1307, 7);
  second = bcdToDec(Wire.read());
  minute = bcdToDec(Wire.read());
  hour = bcdToDec(Wire.read());
  weekday = bcdToDec(Wire.read());
  monthday = bcdToDec(Wire.read());
  month = bcdToDec(Wire.read());
  year = bcdToDec(Wire.read());
}

Update 1:

#include <Wire.h>
const int DS1307 = 0x68; // Address of DS1307 see data sheets
const char* days[] =
{"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};
const char* months[] =
{"January", "February", "March", "April", "May", "June", "July", "August","September", "October", "November", "December"};

// Initializes all values: 
byte second = 0;
byte minute = 0;
byte hour = 0;
byte weekday = 0;
byte monthday = 0;
byte month = 0;
byte year = 0;

void setup() {
  Wire.begin();
  Serial.begin(9600);
  delay(2000); // This delay allows the MCU to read the current date and time.

  Serial.print("The current date and time is: ");
  printTime();
  Serial.println("Please change to newline ending the settings on the lower right of the Serial Monitor");
  Serial.println("Would you like to set the date and time now? Y/N");

  while (!Serial.available()) delay(10);
  if (Serial.read() == 'y' || Serial.read() == 'Y')

  // This set of functions allows the user to change the date and time
  {
    Serial.read();
    setTime();
    Serial.print("The current date and time is now: ");
    printTime();
  }


  Serial.println("Thank you.");
}

// Continuous function for converting bytes to decimals and vice versa
void loop() {
}
byte decToBcd(byte val) {
  return ((val/10*16) + (val%10));
}
byte bcdToDec(byte val) {
  return ((val/16*10) + (val%16));
}


// This set of codes is allows input of data
void setTime() {
  Serial.print("Please enter the current year, 00-99. - ");
  year = readByte();
  Serial.println(year);
  Serial.print("Please enter the current month, 1-12. - ");
  month = readByte();
  Serial.println(months[month-1]);
  Serial.print("Please enter the current day of the month, 1-31. - ");
  monthday = readByte();
  Serial.println(monthday);
  Serial.println("Please enter the current day of the week, 1-7.");
  Serial.print("1 Sun | 2 Mon | 3 Tues | 4 Weds | 5 Thu | 6 Fri | 7 Sat - ");
  weekday = readByte();
  Serial.println(days[weekday-1]);
  Serial.print("Please enter the current hour in 24hr format, 0-23. - ");
  hour = readByte();
  Serial.println(hour);
  Serial.print("Please enter the current minute, 0-59. - ");
  minute = readByte();
  Serial.println(minute);
  second = 0;
  Serial.println("The data has been entered.");

  // The following codes transmits the data to the RTC
  Wire.beginTransmission(DS1307);
  Wire.write(byte(0));
  Wire.write(decToBcd(second));
  Wire.write(decToBcd(minute));
  Wire.write(decToBcd(hour));
  Wire.write(decToBcd(weekday));
  Wire.write(decToBcd(monthday));
  Wire.write(decToBcd(month));
  Wire.write(decToBcd(year));
  Wire.write(byte(0));
  Wire.endTransmission();
  // Ends transmission of data
}


byte readByte() {
  byte reading = 0;
  while (!Serial.available()) delay(10);

  byte incomingByte = Serial.read();
  while (incomingByte != '\r') {
    if (incomingByte >= '0' && incomingByte <= '9')
      reading = reading * 10 + (incomingByte - '0');
    else;
    incomingByte = Serial.read();
  }
  //Serial.flush();
  return reading;
}


void printTime() {
  char buffer[3];
  const char* AMPM = 0;
  readTime();
  Serial.print(days[weekday-1]);
  Serial.print(" ");
  Serial.print(months[month-1]);
  Serial.print(" ");
  Serial.print(monthday);
  Serial.print(", 20");
  Serial.print(year);
  Serial.print(" ");
  if (hour > 12) {
    hour -= 12;
    AMPM = " PM";
  }
  else AMPM = " AM";
  Serial.print(hour);
  Serial.print(":");
  sprintf(buffer, "%02d", minute);
  Serial.print(buffer);
  Serial.println(AMPM);
}


void readTime() {
  Wire.beginTransmission(DS1307);
  Wire.write(byte(0));
  Wire.endTransmission();
  Wire.requestFrom(DS1307, 7);
  second = bcdToDec(Wire.read());
  minute = bcdToDec(Wire.read());
  hour = bcdToDec(Wire.read());
  weekday = bcdToDec(Wire.read());
  monthday = bcdToDec(Wire.read());
  month = bcdToDec(Wire.read());
  year = bcdToDec(Wire.read());
}
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1 Answer 1

Reset to default
1

There are a few problems.

You have an extra Serial.read() before the call to setTime();. This loses a byte.

In readByte() you could be returning an int instead of a byte, but the real problem here is that you should be declaring byte reading = 0; outside the loop. It gets sets to 0 by mistake every loop iteration.

Serial.flush() is for flushing outgoing data since Arduino 1.0. It looks like you mean to be flushing the incoming buffer, which this does not do any more.

The problem with freezing up is probably due to the loop inside readByte(). Some terminals include a '\n' character at the end of a line, but some use '\r', and some use both. You could try checking for '\r' and ignoring '\n'. Your program may be waiting endlessly for a newline character that will never be sent!

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2 Comments

So I deleted the extra Serial.read(), I declared byte reading = 0; after byte year = 0;, I commented out Serial.flush(), and changed '\n' to '\r' in readByte(), but I'm still having issues.
Update your question to the latest version, and describe the new issues. You might actually need that Serial.read(); it looks like it consumes the '\r' character. Declare byte reading = 0; inside the readByte() function, but above the loop. If you declare it globally, then it won't get set to 0 when it needs to be.

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