New and trying to figure out code

I am trying to make a data logger using a DS3231 RTC module with temp and an SD card that also displays on an OLED display. The final is two constantly blinking LED's. I combined a bunch of code, but I am assuming that the blinking LED's are getting hung up with the delay's that are present in the rest of the code. Just looking for some guidance.

CODE:

#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <SD.h>
#include <DS3231.h>

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

#define OLED_RESET 4
Adafruit_SSD1306 display(OLED_RESET);

#define button1 9 // Button B1 is connected to Arduino pin 9
#define button2 8 // Button B2 is connected to Arduino pin 8
#define buzzer 3

//SD Card

File myFile;
DS3231 rtc(SDA, SCL);
int pinCS = 10; // Pin 10 on Arduino Uno

//LEDBLINKNODELAY

// constants won't change. Used here to set a pin number:
const int ledPin1 = A1; // the number of the LED pin
const int ledPin2 = A2;
// Variables will change:
int ledState = LOW; // ledState used to set the LED

// Generally, you should use "unsigned long" for variables that hold time
// The value will quickly become too large for an int to store
unsigned long previousMillis = 0; // will store last time LED was updated

// constants won't change:
const long interval = 1000; // interval at which to blink (milliseconds)

void setup(void) {
//sdcard
Serial.begin(9600);
pinMode(pinCS, OUTPUT);

// SD Card Initialization
if (SD.begin())
{
Serial.println("SD card is ready to use.");
} else
{
Serial.println("SD card initialization failed");
return;
}
rtc.begin();

// set the digital pin as output:
pinMode(ledPin1, OUTPUT);
pinMode(ledPin2, OUTPUT);
//rtc
pinMode(button1, INPUT_PULLUP);
pinMode(button2, INPUT_PULLUP);
pinMode(buzzer, OUTPUT);
digitalWrite(buzzer, HIGH);
delay(1000);
Serial.begin(115200);

// by default, we'll generate the high voltage from the 3.3v line internally! (neat!)
display.begin(SSD1306_SWITCHCAPVCC, 0x3C); // initialize with the I2C addr
// init done

// Clear the display buffer.
display.clearDisplay();
display.display();

display.setTextColor(WHITE,BLACK);
display.drawRect(117, 55, 3, 3, WHITE); // Put degree symbol ( ° )
draw_text(0, 55, "TEMPERATURE =", 1);
draw_text(122, 55, "C", 1);
}

char Time = " : : ";
char Calendar = " / /20 ";
char temperature = " 00.00";
char temperature_msb;
byte i, second, minute, hour, day, date, month, year, temperature_lsb;

void display_day(){
switch(day){
case 1: draw_text(0, 0, " SUNDAY ", 1); break;
case 2: draw_text(0, 0, " MONDAY ", 1); break;
case 3: draw_text(0, 0, " TUESDAY ", 1); break;
case 4: draw_text(0, 0, "WEDNESDAY", 1); break;
case 5: draw_text(0, 0, "THURSDAY ", 1); break;
case 6: draw_text(0, 0, " FRIDAY ", 1); break;
default: draw_text(0, 0, "SATURDAY ", 1);
}
}

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[9] = year % 10 + 48;
Calendar[8] = year / 10 + 48;
Calendar[4] = month % 10 + 48;
Calendar[3] = month / 10 + 48;
Calendar[1] = date % 10 + 48;
Calendar[0] = date / 10 + 48;
if(temperature_msb < 0){
temperature_msb = abs(temperature_msb);
temperature[0] = '-';
}
else
temperature[0] = ' ';
temperature_lsb >>= 6;
temperature[2] = temperature_msb % 10 + 48;
temperature[1] = temperature_msb / 10 + 48;
if(temperature_lsb == 0 || temperature_lsb == 2){
temperature[5] = '0';
if(temperature_lsb == 0) temperature[4] = '0';
else temperature[4] = '5';
}
if(temperature_lsb == 1 || temperature_lsb == 3){
temperature[5] = '5';
if(temperature_lsb == 1) temperature[4] = '2';
else temperature[4] = '7';
}

draw_text(60, 0, Calendar, 1); // Display the date (format: dd/mm/yyyy)
draw_text(10, 24, Time, 2); // Display the time
draw_text(75, 55, temperature, 1); // Display the temperature
if(Time[0]=='2' && Time[1]=='0' && Time[3]== '3' && Time[4]=='0')
{
digitalWrite(buzzer, LOW);
}
else
{
digitalWrite(buzzer, HIGH);
}
}

void blink_parameter(){
byte j = 0;
while(j < 10 && digitalRead(button1) && digitalRead(button2)){
j++;
delay(25);
}
}

byte edit(byte x_pos, byte y_pos, byte parameter){
char text[3];
sprintf(text,"%02u", parameter);
while(!digitalRead(button1)); // Wait until button B1 released
while(true){
while(!digitalRead(button2)){ // If button B2 is pressed
parameter++;
if(i == 0 && parameter > 31) // If date > 31 ==> date = 1
parameter = 1;
if(i == 1 && parameter > 12) // If month > 12 ==> month = 1
parameter = 1;
if(i == 2 && parameter > 99) // If year > 99 ==> year = 0
parameter = 0;
if(i == 3 && parameter > 23) // If hours > 23 ==> hours = 0
parameter = 0;
if(i == 4 && parameter > 59) // If minutes > 59 ==> minutes = 0
parameter = 0;
sprintf(text,"%02u", parameter);
draw_text(x_pos, y_pos, text, 1);
delay(200); // Wait 200ms
}
draw_text(x_pos, y_pos, " ", 1);
blink_parameter();
draw_text(x_pos, y_pos, text, 1);
blink_parameter();
if(!digitalRead(button1)){ // If button B1 is pressed
i++; // Increament 'i' for the next parameter
return parameter; // Return parameter value and exit
}
}
}

void draw_text(byte x_pos, byte y_pos, char *text, byte text_size) {
display.setCursor(x_pos, y_pos);
display.setTextSize(text_size);
display.print(text);
display.display();
}

void loop() {
//sdcard
Serial.print(rtc.getTimeStr());
Serial.print(",");
Serial.println(int(rtc.getTemp()));

myFile = SD.open("test.txt", FILE_WRITE);
if (myFile) {
myFile.print(rtc.getTimeStr());
myFile.print(",");
myFile.println(int(rtc.getTemp()));
myFile.close(); // close the file
}
// if the file didn't open, print an error:
else {
Serial.println("error opening test.txt");
}
delay(3000);
// here is where you'd put code that needs to be running all the time.

// check to see if it's time to blink the LED; that is, if the difference
// between the current time and last time you blinked the LED is bigger than
// the interval at which you want to blink the LED.
unsigned long currentMillis = millis();

if (currentMillis - previousMillis >= interval) {
// save the last time you blinked the LED
previousMillis = currentMillis;

// if the LED is off turn it on and vice-versa:
if (ledState == LOW) {
  ledState = HIGH;
} else {
  ledState = LOW;
}

// set the LED with the ledState of the variable:
digitalWrite(A1, ledState);
digitalWrite(A2, ledState);

}

if(!digitalRead(button1)){ // If button B1 is pressed
i = 0;
while(!digitalRead(button1)); // Wait for button B1 release
while(true){
while(!digitalRead(button2)){ // While button B2 pressed
day++; // Increment day
if(day > 7) day = 1;
display_day(); // Call display_day function
delay(200); // Wait 200 ms
}
draw_text(0, 0, " ", 1);
blink_parameter(); // Call blink_parameter function
display_day(); // Call display_day function
blink_parameter(); // Call blink_parameter function
if(!digitalRead(button1)) // If button B1 is pressed
break;
}
//set position of text when editing on button press
date = edit(60, 0, date); // Edit date
month = edit(80, 0, month); // Edit month
year = edit(110,0, year); // Edit year
hour = edit(14, 9, hour); // Edit hours
minute = edit(50, 9, minute); // Edit minutes

// 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 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);                                 // Wait 200ms

}

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
Wire.beginTransmission(0x68); // Start I2C protocol with DS3231 address
Wire.write(0x11); // Send register address
Wire.endTransmission(false); // I2C restart
Wire.requestFrom(0x68, 2); // Request 2 bytes from DS3231 and release I2C bus at end of reading
temperature_msb = Wire.read(); // Read temperature MSB
temperature_lsb = Wire.read(); // Read temperature LSB

display_day();
DS3231_display(); // Diaplay time & calendar

delay(50); // Wait 50ms
}

If You would use autoformat, or Ctrl T, in the IDE and then code tags when posting the code many helpers would be more satisfied.

Did You try each of the different codes applied to their hardware befor joining them? That's the way recommended.

What is the desired action of the code and what exactly is the current outcome? Please be more precise.

Each code works independently yes, and the code works as it is minus the blinking led's, they stay lit throughout the duration.

THe code should read and display date time and temp on the OLED display. Log the time and temp to the SD card and blink the LED's. It is displaying the date time and temp on the OLED Display and logging the data to the SD card, the LED's stay lit for the duration of the code.

I will do that in the future, and try to edit the code currently. Sorry, it is my first post so I was not even sure how the favorable format for the code would be.

You can't make Blink Without Delay work, combined with delay(3000). There is no such thing as "half multitasking". You have to go all in. It will only work with no delay() calls in loop().

Please:

In the Arduino IDE, use Ctrl T or CMD T to format your code then copy the complete sketch.

Use the </> icon from the ‘reply menu’ to attach the copied sketch.

Well done anyway! Testing code the way You did, piece by piece. I'll take a look at the blink build when You upgrade the code presentation. Using the mobile now....

I hope this works for the code. Thank you guys.

aarg: How do you convert the delay (3000) to no delay?

LarryD: Thank you for the Icon so I can paste the code. I did the formatting and copied/pasted the code. I hope it came out alright.

type [code]
#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <SD.h>
#include <DS3231.h>

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

#define OLED_RESET 4
Adafruit_SSD1306 display(OLED_RESET);

#define button1    9                       // Button B1 is connected to Arduino pin 9
#define button2    8                       // Button B2 is connected to Arduino pin 8
#define buzzer     3

//SD Card


File myFile;
DS3231  rtc(SDA, SCL);
int pinCS = 10; // Pin 10 on Arduino Uno

//LEDBLINKNODELAY

// constants won't change. Used here to set a pin number:
const int ledPin1 =  A1;     // the number of the LED pin
const int ledPin2 =  A2;
// Variables will change:
int ledState = LOW;             // ledState used to set the LED

// Generally, you should use "unsigned long" for variables that hold time
// The value will quickly become too large for an int to store
unsigned long previousMillis = 0;        // will store last time LED was updated

// constants won't change:
const long interval = 1000;           // interval at which to blink (milliseconds)


void setup(void) {
  //sdcard
  Serial.begin(9600);
  pinMode(pinCS, OUTPUT);

  // SD Card Initialization
  if (SD.begin())
  {
    Serial.println("SD card is ready to use.");
  } else
  {
    Serial.println("SD card initialization failed");
    return;
  }
  rtc.begin();

  // set the digital pin as output:
  pinMode(ledPin1, OUTPUT);
  pinMode(ledPin2, OUTPUT);
  //rtc
  pinMode(button1, INPUT_PULLUP);
  pinMode(button2, INPUT_PULLUP);
  pinMode(buzzer, OUTPUT);
  digitalWrite(buzzer, HIGH);
  delay(1000);
  Serial.begin(115200);

  // by default, we'll generate the high voltage from the 3.3v line internally! (neat!)
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);  // initialize with the I2C addr
  // init done

  // Clear the display buffer.
  display.clearDisplay();
  display.display();

  display.setTextColor(WHITE, BLACK);
  display.drawRect(117, 55, 3, 3, WHITE);     // Put degree symbol ( ° )
  draw_text(0, 55, "TEMPERATURE =", 1);
  draw_text(122, 55, "C", 1);
}

char Time[]     = "  :  :  ";
char Calendar[] = "  /  /20  ";
char temperature[] = " 00.00";
char temperature_msb;
byte i, second, minute, hour, day, date, month, year, temperature_lsb;

void display_day() {
  switch (day) {
    case 1:  draw_text(0, 0, " SUNDAY  ", 1); break;
    case 2:  draw_text(0, 0, " MONDAY  ", 1); break;
    case 3:  draw_text(0, 0, " TUESDAY ", 1); break;
    case 4:  draw_text(0, 0, "WEDNESDAY", 1); break;
    case 5:  draw_text(0, 0, "THURSDAY ", 1); break;
    case 6:  draw_text(0, 0, " FRIDAY  ", 1); break;
    default: draw_text(0, 0, "SATURDAY ", 1);
  }
}

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[9] = year   % 10 + 48;
  Calendar[8] = year   / 10 + 48;
  Calendar[4] = month  % 10 + 48;
  Calendar[3] = month  / 10 + 48;
  Calendar[1] = date   % 10 + 48;
  Calendar[0] = date   / 10 + 48;
  if (temperature_msb < 0) {
    temperature_msb = abs(temperature_msb);
    temperature[0] = '-';
  }
  else
    temperature[0] = ' ';
  temperature_lsb >>= 6;
  temperature[2] = temperature_msb % 10  + 48;
  temperature[1] = temperature_msb / 10  + 48;
  if (temperature_lsb == 0 || temperature_lsb == 2) {
    temperature[5] = '0';
    if (temperature_lsb == 0) temperature[4] = '0';
    else                     temperature[4] = '5';
  }
  if (temperature_lsb == 1 || temperature_lsb == 3) {
    temperature[5] = '5';
    if (temperature_lsb == 1) temperature[4] = '2';
    else                     temperature[4] = '7';
  }

  draw_text(60,  0, Calendar, 1);                     // Display the date (format: dd/mm/yyyy)
  draw_text(10, 24, Time, 2);                         // Display the time
  draw_text(75, 55, temperature, 1);                  // Display the temperature
  if (Time[0] == '2' && Time[1] == '0' && Time[3] == '3' && Time[4] == '0')
  {
    digitalWrite(buzzer, LOW);
  }
  else
  {
    digitalWrite(buzzer, HIGH);
  }
}

void blink_parameter() {
  byte j = 0;
  while (j < 10 && digitalRead(button1) && digitalRead(button2)) {
    j++;
    delay(25);
  }
}

byte edit(byte x_pos, byte y_pos, byte parameter) {
  char text[3];
  sprintf(text, "%02u", parameter);
  while (!digitalRead(button1));                     // Wait until button B1 released
  while (true) {
    while (!digitalRead(button2)) {                  // If button B2 is pressed
      parameter++;
      if (i == 0 && parameter > 31)                  // If date > 31 ==> date = 1
        parameter = 1;
      if (i == 1 && parameter > 12)                  // If month > 12 ==> month = 1
        parameter = 1;
      if (i == 2 && parameter > 99)                  // If year > 99 ==> year = 0
        parameter = 0;
      if (i == 3 && parameter > 23)                  // If hours > 23 ==> hours = 0
        parameter = 0;
      if (i == 4 && parameter > 59)                  // If minutes > 59 ==> minutes = 0
        parameter = 0;
      sprintf(text, "%02u", parameter);
      draw_text(x_pos, y_pos, text, 1);
      delay(200);                                    // Wait 200ms
    }
    draw_text(x_pos, y_pos, "  ", 1);
    blink_parameter();
    draw_text(x_pos, y_pos, text, 1);
    blink_parameter();
    if (!digitalRead(button1)) {                     // If button B1 is pressed
      i++;                                           // Increament 'i' for the next parameter
      return parameter;                              // Return parameter value and exit
    }
  }
}

void draw_text(byte x_pos, byte y_pos, char *text, byte text_size) {
  display.setCursor(x_pos, y_pos);
  display.setTextSize(text_size);
  display.print(text);
  display.display();
}

void loop() {
  // the interval at which you want to blink the LED.
  unsigned long currentMillis = millis();

  if (currentMillis - previousMillis >= interval) {
    // save the last time you blinked the LED
    previousMillis = currentMillis;

    // if the LED is off turn it on and vice-versa:
    if (ledState == LOW) {
      ledState = HIGH;
    } else {
      ledState = LOW;
    }

    // set the LED with the ledState of the variable:
    digitalWrite(A1, ledState);
    digitalWrite(A2, ledState);
  }

  if (!digitalRead(button1)) {                       // If button B1 is pressed
    i = 0;
    while (!digitalRead(button1));                   // Wait for button B1 release
    while (true) {
      while (!digitalRead(button2)) {                // While button B2 pressed
        day++;                                       // Increment day
        if (day > 7) day = 1;
        display_day();                               // Call display_day function
        delay(200);                                  // Wait 200 ms
      }
      draw_text(0, 0, "         ", 1);
      blink_parameter();                             // Call blink_parameter function
      display_day();                                 // Call display_day function
      blink_parameter();                             // Call blink_parameter function
      if (!digitalRead(button1))                     // If button B1 is pressed
        break;
    }
    //set position of text when editing on button press
    date   = edit(60, 0, date);                      // Edit date
    month  = edit(80, 0, month);                    // Edit month
    year   = edit(110, 0, year);                   // Edit year
    hour   = edit(14, 9, hour);                     // Edit hours
    minute = edit(50, 9, minute);                   // Edit minutes

    // 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 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);                                 // Wait 200ms
  }

  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
  Wire.beginTransmission(0x68);                 // Start I2C protocol with DS3231 address
  Wire.write(0x11);                             // Send register address
  Wire.endTransmission(false);                  // I2C restart
  Wire.requestFrom(0x68, 2);                    // Request 2 bytes from DS3231 and release I2C bus at end of reading
  temperature_msb = Wire.read();                // Read temperature MSB
  temperature_lsb = Wire.read();                // Read temperature LSB

  display_day();
  DS3231_display();                             // Diaplay time & calendar

  delay(50);                                    // Wait 50ms

  //SD card
  //sdcard
  Serial.print(rtc.getTimeStr());
  Serial.print(",");
  Serial.println(int(rtc.getTemp()));

  myFile = SD.open("test.txt", FILE_WRITE);
  if (myFile) {
    myFile.print(rtc.getTimeStr());
    myFile.print(",");
    myFile.println(int(rtc.getTemp()));
    myFile.close(); // close the file
  }
  // if the file didn't open, print an error:
  else {
    Serial.println("error opening test.txt");
  }
  delay(3000);
}
[/code]or paste code here

What is the purpose of the 3 second delay? Do you only want to display the date and time every 3 seconds?

the 3 second delay was for writing the data to the SD card.

Handle logging like you did the LED.

#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <SD.h>
#include <DS3231.h>

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

#define OLED_RESET 4
Adafruit_SSD1306 display(OLED_RESET);

#define button1    9                       // Button B1 is connected to Arduino pin 9
#define button2    8                       // Button B2 is connected to Arduino pin 8
#define buzzer     3

//SD Card


File myFile;
DS3231  rtc(SDA, SCL);
int pinCS = 10; // Pin 10 on Arduino Uno

//LEDBLINKNODELAY

// constants won't change. Used here to set a pin number:
const int ledPin1 =  A1;     // the number of the LED pin
const int ledPin2 =  A2;
// Variables will change:
int ledState = LOW;             // ledState used to set the LED

// Generally, you should use "unsigned long" for variables that hold time
// The value will quickly become too large for an int to store
unsigned long previousMillisBlink = 0;        // will store last time LED was updated
unsigned long previousMillisLog = 0;        // will store last time LED was updated

// constants won't change:
const long blinkInterval = 1000;           // interval at which to blink (milliseconds)
const long logInterval = 3000;           // interval at which to log


void setup(void) {
  //sdcard
  Serial.begin(9600);
  pinMode(pinCS, OUTPUT);

  // SD Card Initialization
  if (SD.begin())
  {
    Serial.println("SD card is ready to use.");
  } else
  {
    Serial.println("SD card initialization failed");
    return;
  }
  rtc.begin();

  // set the digital pin as output:
  pinMode(ledPin1, OUTPUT);
  pinMode(ledPin2, OUTPUT);
  //rtc
  pinMode(button1, INPUT_PULLUP);
  pinMode(button2, INPUT_PULLUP);
  pinMode(buzzer, OUTPUT);
  digitalWrite(buzzer, HIGH);
  delay(1000);
  Serial.begin(115200);

  // by default, we'll generate the high voltage from the 3.3v line internally! (neat!)
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);  // initialize with the I2C addr
  // init done

  // Clear the display buffer.
  display.clearDisplay();
  display.display();

  display.setTextColor(WHITE, BLACK);
  display.drawRect(117, 55, 3, 3, WHITE);     // Put degree symbol ( ° )
  draw_text(0, 55, "TEMPERATURE =", 1);
  draw_text(122, 55, "C", 1);
}

char Time[]     = "  :  :  ";
char Calendar[] = "  /  /20  ";
char temperature[] = " 00.00";
char temperature_msb;
byte i, second, minute, hour, day, date, month, year, temperature_lsb;

void display_day() {
  switch (day) {
    case 1:  draw_text(0, 0, " SUNDAY  ", 1); break;
    case 2:  draw_text(0, 0, " MONDAY  ", 1); break;
    case 3:  draw_text(0, 0, " TUESDAY ", 1); break;
    case 4:  draw_text(0, 0, "WEDNESDAY", 1); break;
    case 5:  draw_text(0, 0, "THURSDAY ", 1); break;
    case 6:  draw_text(0, 0, " FRIDAY  ", 1); break;
    default: draw_text(0, 0, "SATURDAY ", 1);
  }
}

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[9] = year   % 10 + 48;
  Calendar[8] = year   / 10 + 48;
  Calendar[4] = month  % 10 + 48;
  Calendar[3] = month  / 10 + 48;
  Calendar[1] = date   % 10 + 48;
  Calendar[0] = date   / 10 + 48;
  if (temperature_msb < 0) {
    temperature_msb = abs(temperature_msb);
    temperature[0] = '-';
  }
  else
    temperature[0] = ' ';
  temperature_lsb >>= 6;
  temperature[2] = temperature_msb % 10  + 48;
  temperature[1] = temperature_msb / 10  + 48;
  if (temperature_lsb == 0 || temperature_lsb == 2) {
    temperature[5] = '0';
    if (temperature_lsb == 0) temperature[4] = '0';
    else                     temperature[4] = '5';
  }
  if (temperature_lsb == 1 || temperature_lsb == 3) {
    temperature[5] = '5';
    if (temperature_lsb == 1) temperature[4] = '2';
    else                     temperature[4] = '7';
  }

  draw_text(60,  0, Calendar, 1);                     // Display the date (format: dd/mm/yyyy)
  draw_text(10, 24, Time, 2);                         // Display the time
  draw_text(75, 55, temperature, 1);                  // Display the temperature
  if (Time[0] == '2' && Time[1] == '0' && Time[3] == '3' && Time[4] == '0')
  {
    digitalWrite(buzzer, LOW);
  }
  else
  {
    digitalWrite(buzzer, HIGH);
  }
}

void blink_parameter() {
  byte j = 0;
  while (j < 10 && digitalRead(button1) && digitalRead(button2)) {
    j++;
    delay(25);
  }
}

byte edit(byte x_pos, byte y_pos, byte parameter) {
  char text[3];
  sprintf(text, "%02u", parameter);
  while (!digitalRead(button1));                     // Wait until button B1 released
  while (true) {
    while (!digitalRead(button2)) {                  // If button B2 is pressed
      parameter++;
      if (i == 0 && parameter > 31)                  // If date > 31 ==> date = 1
        parameter = 1;
      if (i == 1 && parameter > 12)                  // If month > 12 ==> month = 1
        parameter = 1;
      if (i == 2 && parameter > 99)                  // If year > 99 ==> year = 0
        parameter = 0;
      if (i == 3 && parameter > 23)                  // If hours > 23 ==> hours = 0
        parameter = 0;
      if (i == 4 && parameter > 59)                  // If minutes > 59 ==> minutes = 0
        parameter = 0;
      sprintf(text, "%02u", parameter);
      draw_text(x_pos, y_pos, text, 1);
      delay(200);                                    // Wait 200ms
    }
    draw_text(x_pos, y_pos, "  ", 1);
    blink_parameter();
    draw_text(x_pos, y_pos, text, 1);
    blink_parameter();
    if (!digitalRead(button1)) {                     // If button B1 is pressed
      i++;                                           // Increament 'i' for the next parameter
      return parameter;                              // Return parameter value and exit
    }
  }
}

void draw_text(byte x_pos, byte y_pos, char *text, byte text_size) {
  display.setCursor(x_pos, y_pos);
  display.setTextSize(text_size);
  display.print(text);
  display.display();
}

void loop() {
  // the interval at which you want to blink the LED.
  unsigned long currentMillis = millis();

  if (currentMillis - previousMillisBlink >= blinkInterval) {
    // save the last time you blinked the LED
    previousMillisBlink = currentMillis;

    // if the LED is off turn it on and vice-versa:
    if (ledState == LOW) {
      ledState = HIGH;
    } else {
      ledState = LOW;
    }

    // set the LED with the ledState of the variable:
    digitalWrite(A1, ledState);
    digitalWrite(A2, ledState);
  }

  if (!digitalRead(button1)) {                       // If button B1 is pressed
    i = 0;
    while (!digitalRead(button1));                   // Wait for button B1 release
    while (true) {
      while (!digitalRead(button2)) {                // While button B2 pressed
        day++;                                       // Increment day
        if (day > 7) day = 1;
        display_day();                               // Call display_day function
        delay(200);                                  // Wait 200 ms
      }
      draw_text(0, 0, "         ", 1);
      blink_parameter();                             // Call blink_parameter function
      display_day();                                 // Call display_day function
      blink_parameter();                             // Call blink_parameter function
      if (!digitalRead(button1))                     // If button B1 is pressed
        break;
    }
    //set position of text when editing on button press
    date   = edit(60, 0, date);                      // Edit date
    month  = edit(80, 0, month);                    // Edit month
    year   = edit(110, 0, year);                   // Edit year
    hour   = edit(14, 9, hour);                     // Edit hours
    minute = edit(50, 9, minute);                   // Edit minutes

    // 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 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);                                 // Wait 200ms
  }

  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
  Wire.beginTransmission(0x68);                 // Start I2C protocol with DS3231 address
  Wire.write(0x11);                             // Send register address
  Wire.endTransmission(false);                  // I2C restart
  Wire.requestFrom(0x68, 2);                    // Request 2 bytes from DS3231 and release I2C bus at end of reading
  temperature_msb = Wire.read();                // Read temperature MSB
  temperature_lsb = Wire.read();                // Read temperature LSB

  display_day();
  DS3231_display();                             // Diaplay time & calendar

  delay(50);                                    // Wait 50ms

  if (currentMillis - previousMillisLog >= logInterval) {
    // save the last time you blinked the LED
    previousMillisLog = currentMillis;
    //SD card
    //sdcard
    Serial.print(rtc.getTimeStr());
    Serial.print(",");
    Serial.println(int(rtc.getTemp()));
  
    myFile = SD.open("test.txt", FILE_WRITE);
    if (myFile) {
      myFile.print(rtc.getTimeStr());
      myFile.print(",");
      myFile.println(int(rtc.getTemp()));
      myFile.close(); // close the file
    }
    // if the file didn't open, print an error:
    else {
      Serial.println("error opening test.txt");
    }
  }
}

If your 3 second delay is after the write, the write has already been done, so delay serves NO purpose.
Paul

Ok, I am starting over. The following code works as expected. LED's blink on time and the display works showing date, time, and temperature. I want to add the ability to log it to an SD card with timestamp and temperature every 5 seconds (previously 3). I have an SD card module model similar to Amazon Link . Chipselect that works is 10 with it hooked up like the following:
MISO=D12
MOSI=D11
SCK=D13
CS=D10

What code can I add to get the SD Card to log within this code?

BLINK_Display_CLOCK_TEMP

[code]
#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels
#define OLED_RESET 4
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
#define button1 9 // Button B1 is connected to Arduino pin 9
#define button2 8 // Button B2 is connected to Arduino pin 8
#define buzzer 3

// constants won't change. Used here to set a pin number:
const int ledPin =  LED_BUILTIN;// the number of the LED pin

// Variables will change:
int ledState = LOW;             // ledState used to set the LED

// Generally, you should use "unsigned long" for variables that hold time
// The value will quickly become too large for an int to store
unsigned long previousMillis = 0;        // will store last time LED was updated

// constants won't change:
const long interval = 1000;           // interval at which to blink (milliseconds)

void setup(void) {
  pinMode(ledPin, OUTPUT);
  pinMode(button1, INPUT_PULLUP);
  pinMode(button2, INPUT_PULLUP);
  pinMode(buzzer, OUTPUT);
  digitalWrite(buzzer, HIGH);
  delay(1000);
  Serial.begin(115200);
  // by default, we'll generate the high voltage from the 3.3v line internally! (neat!)
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C); // initialize with the I2C addr
  // init done
  // Clear the display buffer.
  display.clearDisplay();
  display.display();
  display.setTextColor(WHITE, BLACK);
  display.drawRect(117, 55, 3, 3, WHITE); // Put degree symbol ( ° )
  draw_text(0, 55, "TEMPERATURE = ", 1);
  draw_text(122, 55, "C", 1);
}
char Time[] = "  :  :  ";
char Calendar[] = "  /  /20  ";
char temperature[] = " 00.00 ";
char temperature_msb;
byte i, second, minute, hour, day, date, month, year, temperature_lsb;
void display_day() {
  switch (day) {
    case 1: draw_text(0, 0, " SUNDAY ", 1); break;
    case 2: draw_text(0, 0, " MONDAY ", 1); break;
    case 3: draw_text(0, 0, " TUESDAY ", 1); break;
    case 4: draw_text(0, 0, "WEDNESDAY", 1); break;
    case 5: draw_text(0, 0, "THURSDAY ", 1); break;
    case 6: draw_text(0, 0, " FRIDAY ", 1); break;
    default: draw_text(0, 0, "SATURDAY ", 1);
  }
}
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[9] = year % 10 + 48;
  Calendar[8] = year / 10 + 48;
  Calendar[4] = month % 10 + 48;
  Calendar[3] = month / 10 + 48;
  Calendar[1] = date % 10 + 48;
  Calendar[0] = date / 10 + 48;
  if (temperature_msb < 0) {
    temperature_msb = abs(temperature_msb);
    temperature[0] = '-';
  }
  else
    temperature[0] = ' ';
  temperature_lsb >>= 6;
  temperature[2] = temperature_msb % 10 + 48;
  temperature[1] = temperature_msb / 10 + 48;
  if (temperature_lsb == 0 || temperature_lsb == 2) {
    temperature[5] = '0';
    if (temperature_lsb == 0) temperature[4] = '0';
    else temperature[4] = '5';
  }
  if (temperature_lsb == 1 || temperature_lsb == 3) {
    temperature[5] = '5';
    if (temperature_lsb == 1) temperature[4] = '2';
    else temperature[4] = '7';
  }
  draw_text(60, 0, Calendar, 1); // Display the date (format: dd/mm/yyyy)
  draw_text(10, 24, Time, 2); // Display the time
  draw_text(75, 55, temperature, 1); // Display the temperature
  if (Time[0] == '2' && Time[1] == '0' && Time[3] == '3' && Time[4] == '0')
  {
    digitalWrite(buzzer, LOW);
  }
  else
  {
    digitalWrite(buzzer, HIGH);
  }
}
void blink_parameter() {
  byte j = 0;
  while ( j < 10 && digitalRead(button1) && digitalRead(button2)) {
    j++;
    delay(25);
  }
}
byte edit(byte x_pos, byte y_pos, byte parameter) {
  char text[3];
  sprintf(text, "%02u", parameter);
  while (!digitalRead(button1)); // Wait until button B1 released
  while (true) {
    while (!digitalRead(button2)) { // If button B2 is pressed
      parameter++;
      if (i == 0 && parameter > 31) // If date > 31 ==> date = 1
        parameter = 1;
      if (i == 1 && parameter > 12) // If month > 12 ==> month = 1
        parameter = 1;
      if (i == 2 && parameter > 99) // If year > 99 ==> year = 0
        parameter = 0;
      if (i == 3 && parameter > 23) // If hours > 23 ==> hours = 0
        parameter = 0;
      if (i == 4 && parameter > 59) // If minutes > 59 ==> minutes = 0
        parameter = 0;
      sprintf(text, "%02u", parameter);
      draw_text(x_pos, y_pos, text, 1);
      delay(200); // Wait 200ms
    }
    draw_text(x_pos, y_pos, " ", 1);
    blink_parameter();
    draw_text(x_pos, y_pos, text, 1);
    blink_parameter();
    if (!digitalRead(button1)) { // If button B1 is pressed
      i++; // Increament 'i' for the next parameter
      return parameter; // Return parameter value and exit
    }
  }
}
void draw_text(byte x_pos, byte y_pos, char *text, byte text_size) {
  display.setCursor(x_pos, y_pos);
  display.setTextSize(text_size);
  display.print(text);
  display.display();
}
void loop() {
  if (!digitalRead(button1)) { // If button B1 is pressed
    i = 0;
    while (!digitalRead(button1)); // Wait for button B1 release
    while (true) {
      while (!digitalRead(button2)) { // While button B2 pressed
        day++; // Increment day
        if (day > 7) day = 1;
        display_day(); // Call display_day function
        delay(200); // Wait 200 ms
      }
      draw_text(0, 0, " ", 1);
      blink_parameter(); // Call blink_parameter function
      display_day(); // Call display_day function
      blink_parameter(); // Call blink_parameter function
      if (!digitalRead(button1)) // If button B1 is pressed
        break;
    }
    //set position of text when editing on button press
    date = edit(60, 0, date); // Edit date
    month = edit(80, 0, month); // Edit month
    year = edit(110, 0, year); // Edit year
    hour = edit(14, 9, hour); // Edit hours
    minute = edit(50, 9, minute); // Edit minutes
    // 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 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); // Wait 200ms
  }
  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
  Wire.beginTransmission(0x68); // Start I2C protocol with DS3231 address
  Wire.write(0x11); // Send register address
  Wire.endTransmission(false); // I2C restart
  Wire.requestFrom(0x68, 2); // Request 2 bytes from DS3231 and release I2C
  //bus at end of reading
  temperature_msb = Wire.read(); // Read temperature MSB
  temperature_lsb = Wire.read(); // Read temperature LSB
  display_day();
  DS3231_display(); // Diaplay time & calendar
  delay(50); // Wait 50ms

  unsigned long currentMillis = millis();

  if (currentMillis - previousMillis >= interval) {
    // save the last time you blinked the LED
    previousMillis = currentMillis;

    // if the LED is off turn it on and vice-versa:
    if (ledState == LOW) {
      ledState = HIGH;
    } else {
      ledState = LOW;
    }

    // set the LED with the ledState of the variable:
    digitalWrite(ledPin, ledState);
  }
}
[/code]

What was wrong with the code I gave you? Just change the logInterval to 5000.

ToddL

It now didn't want to start the display or blink the lights. I am thinking that what I uploaded I messed up somewhere in addition to the sd card portion that you fixed. It was writing to the sd card as expected, so the code that you fixed was working. I decided to start from a known good code where the portion for the sd card just needed to be added in since even after you fixed that code the rest was still having issues. I just wanted to give the best base for anyone to start with.

OK. Then just handle the logging like you do the LEDs, except every 5 seconds.

#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels
#define OLED_RESET 4
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
#define button1 9 // Button B1 is connected to Arduino pin 9
#define button2 8 // Button B2 is connected to Arduino pin 8
#define buzzer 3

// constants won't change. Used here to set a pin number:
const int ledPin =  LED_BUILTIN;// the number of the LED pin

// Variables will change:
int ledState = LOW;             // ledState used to set the LED

// Generally, you should use "unsigned long" for variables that hold time
// The value will quickly become too large for an int to store
unsigned long previousMillis = 0;        // will store last time LED was updated
unsigned long previousMillisLog = 0;
// constants won't change:
const long interval = 1000;           // interval at which to blink (milliseconds)
const unsigned long logInterval = 5000; // *** ADD LOGGING

void setup(void) {
  pinMode(ledPin, OUTPUT);
  pinMode(button1, INPUT_PULLUP);
  pinMode(button2, INPUT_PULLUP);
  pinMode(buzzer, OUTPUT);
  digitalWrite(buzzer, HIGH);
  delay(1000);
  Serial.begin(115200);
  // by default, we'll generate the high voltage from the 3.3v line internally! (neat!)
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C); // initialize with the I2C addr
  // init done
  // Clear the display buffer.
  display.clearDisplay();
  display.display();
  display.setTextColor(WHITE, BLACK);
  display.drawRect(117, 55, 3, 3, WHITE); // Put degree symbol ( ° )
  draw_text(0, 55, "TEMPERATURE = ", 1);
  draw_text(122, 55, "C", 1);
}
char Time[] = "  :  :  ";
char Calendar[] = "  /  /20  ";
char temperature[] = " 00.00 ";
char temperature_msb;
byte i, second, minute, hour, day, date, month, year, temperature_lsb;
void display_day() {
  switch (day) {
    case 1: draw_text(0, 0, " SUNDAY ", 1); break;
    case 2: draw_text(0, 0, " MONDAY ", 1); break;
    case 3: draw_text(0, 0, " TUESDAY ", 1); break;
    case 4: draw_text(0, 0, "WEDNESDAY", 1); break;
    case 5: draw_text(0, 0, "THURSDAY ", 1); break;
    case 6: draw_text(0, 0, " FRIDAY ", 1); break;
    default: draw_text(0, 0, "SATURDAY ", 1);
  }
}
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[9] = year % 10 + 48;
  Calendar[8] = year / 10 + 48;
  Calendar[4] = month % 10 + 48;
  Calendar[3] = month / 10 + 48;
  Calendar[1] = date % 10 + 48;
  Calendar[0] = date / 10 + 48;
  if (temperature_msb < 0) {
    temperature_msb = abs(temperature_msb);
    temperature[0] = '-';
  }
  else
    temperature[0] = ' ';
  temperature_lsb >>= 6;
  temperature[2] = temperature_msb % 10 + 48;
  temperature[1] = temperature_msb / 10 + 48;
  if (temperature_lsb == 0 || temperature_lsb == 2) {
    temperature[5] = '0';
    if (temperature_lsb == 0) temperature[4] = '0';
    else temperature[4] = '5';
  }
  if (temperature_lsb == 1 || temperature_lsb == 3) {
    temperature[5] = '5';
    if (temperature_lsb == 1) temperature[4] = '2';
    else temperature[4] = '7';
  }
  draw_text(60, 0, Calendar, 1); // Display the date (format: dd/mm/yyyy)
  draw_text(10, 24, Time, 2); // Display the time
  draw_text(75, 55, temperature, 1); // Display the temperature
  if (Time[0] == '2' && Time[1] == '0' && Time[3] == '3' && Time[4] == '0')
  {
    digitalWrite(buzzer, LOW);
  }
  else
  {
    digitalWrite(buzzer, HIGH);
  }
}
void blink_parameter() {
  byte j = 0;
  while ( j < 10 && digitalRead(button1) && digitalRead(button2)) {
    j++;
    delay(25);
  }
}
byte edit(byte x_pos, byte y_pos, byte parameter) {
  char text[3];
  sprintf(text, "%02u", parameter);
  while (!digitalRead(button1)); // Wait until button B1 released
  while (true) {
    while (!digitalRead(button2)) { // If button B2 is pressed
      parameter++;
      if (i == 0 && parameter > 31) // If date > 31 ==> date = 1
        parameter = 1;
      if (i == 1 && parameter > 12) // If month > 12 ==> month = 1
        parameter = 1;
      if (i == 2 && parameter > 99) // If year > 99 ==> year = 0
        parameter = 0;
      if (i == 3 && parameter > 23) // If hours > 23 ==> hours = 0
        parameter = 0;
      if (i == 4 && parameter > 59) // If minutes > 59 ==> minutes = 0
        parameter = 0;
      sprintf(text, "%02u", parameter);
      draw_text(x_pos, y_pos, text, 1);
      delay(200); // Wait 200ms
    }
    draw_text(x_pos, y_pos, " ", 1);
    blink_parameter();
    draw_text(x_pos, y_pos, text, 1);
    blink_parameter();
    if (!digitalRead(button1)) { // If button B1 is pressed
      i++; // Increament 'i' for the next parameter
      return parameter; // Return parameter value and exit
    }
  }
}
void draw_text(byte x_pos, byte y_pos, char *text, byte text_size) {
  display.setCursor(x_pos, y_pos);
  display.setTextSize(text_size);
  display.print(text);
  display.display();
}
void loop() {
  if (!digitalRead(button1)) { // If button B1 is pressed
    i = 0;
    while (!digitalRead(button1)); // Wait for button B1 release
    while (true) {
      while (!digitalRead(button2)) { // While button B2 pressed
        day++; // Increment day
        if (day > 7) day = 1;
        display_day(); // Call display_day function
        delay(200); // Wait 200 ms
      }
      draw_text(0, 0, " ", 1);
      blink_parameter(); // Call blink_parameter function
      display_day(); // Call display_day function
      blink_parameter(); // Call blink_parameter function
      if (!digitalRead(button1)) // If button B1 is pressed
        break;
    }
    //set position of text when editing on button press
    date = edit(60, 0, date); // Edit date
    month = edit(80, 0, month); // Edit month
    year = edit(110, 0, year); // Edit year
    hour = edit(14, 9, hour); // Edit hours
    minute = edit(50, 9, minute); // Edit minutes
    // 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 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); // Wait 200ms
  }
  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
  Wire.beginTransmission(0x68); // Start I2C protocol with DS3231 address
  Wire.write(0x11); // Send register address
  Wire.endTransmission(false); // I2C restart
  Wire.requestFrom(0x68, 2); // Request 2 bytes from DS3231 and release I2C
  //bus at end of reading
  temperature_msb = Wire.read(); // Read temperature MSB
  temperature_lsb = Wire.read(); // Read temperature LSB
  display_day();
  DS3231_display(); // Diaplay time & calendar
  delay(50); // Wait 50ms

  unsigned long currentMillis = millis();

  if (currentMillis - previousMillis >= interval) {
    // save the last time you blinked the LED
    previousMillis = currentMillis;

    // if the LED is off turn it on and vice-versa:
    if (ledState == LOW) {
      ledState = HIGH;
    } else {
      ledState = LOW;
    }

    // set the LED with the ledState of the variable:
    digitalWrite(ledPin, ledState);
  }
  
  // *** ADD LOGGING
  if (currentMillis - previousMillisLog >= logIinterval) {
    previousMillisLog = currentMillis;

    //SD card
    //sdcard
    Serial.print(rtc.getTimeStr());
    Serial.print(",");
    Serial.println(int(rtc.getTemp()));
  
    myFile = SD.open("test.txt", FILE_WRITE);
    if (myFile) {
      myFile.print(rtc.getTimeStr());
      myFile.print(",");
      myFile.println(int(rtc.getTemp()));
      myFile.close(); // close the file
    }
    // if the file didn't open, print an error:
    else {
      Serial.println("error opening test.txt");
    }
  }
}

Just wanted to update everyone and a big thanks. I found out that the Nano I was using did not have enough RAM to run both the SD card and the OLED display. All things are working now and I revised my code into "pockets" so I could comment things and test them individually. Anyway, Just wanted to give a big thank you as you guys really helped me out, I learned a ton on this project!

Mike

[code]
#include <Wire.h>
#include "RTClib.h"                    //Jeelab's fantastic RTC library.
#include<SPI.h>                        //SD card uses spi bus
#include<SD.h>                         //contains library functions
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128                // OLED display width, in pixels
#define SCREEN_HEIGHT 64               // OLED display height, in pixels
#define OLED_RESET 4

#define CSPIN      10                   //if using DPin-4, it does not require to set direction
#define button1    9                   //Button B1 is connected to Arduino pin 9
#define button2    8                 //Button B2 is connected to Arduino pin 10


File myFile;                           //file pointer variavle declaration
Adafruit_SSD1306 display(OLED_RESET);
RTC_DS3231 rtc;                        //RTC definition

const int ledPin1 =  A1;// the number of the LED pin
const int ledPin2 =  A2;
int ledState = LOW;             // ledState used to set the LED
unsigned long LEDpreviousMillis = 0;        // will store last time LED was updated
unsigned long SDpreviousMillis = 0;
const long LEDinterval = 2000;           // interval at which to blink (milliseconds)
const long SDinterval = 50000;

void setup(void) {
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);  // initialize with the I2C addr
  display.clearDisplay();
  display.display();
  display.setTextColor(WHITE, BLACK);
  display.drawRect(117, 55, 3, 3, WHITE);     // Put degree symbol ( ° )
  draw_text(0, 55, "TEMPERATURE =", 1);
  draw_text(122, 55, "C", 1);
  pinMode(A1, OUTPUT);
  pinMode(A2, OUTPUT);
  Serial.begin(9600);
  Wire.begin();
  rtc.begin();
  rtc.adjust(DateTime(F(__DATE__), F(__TIME__)));        //-Not sure if this is needed as the RTC is currently set
  //rtc.adjust(DateTime(2021, 12, 31, 11, 59, 57));      //set date-time manualy:yr,mo,dy,hr,mn,sec
  pinMode(button1, INPUT_PULLUP);
  pinMode(button2, INPUT_PULLUP);
  pinMode(CSPIN, OUTPUT);
  delay(1000);
  if (!SD.begin(CSPIN))
  {
    Serial.println("Card failed, or not present");
    return;
  }
  Serial.println("card initialized.");
  SD.begin(CSPIN);                                     //SD Card is initialized
  //SD.remove("TEST.txt");                               //remove any existing file with this name
  if (SD.exists("flight.txt")) {
    Serial.println("flight.txt exists.");
  } else {
    Serial.println("flight.txt doesn't exist.");
  }
  // open a new file and immediately close it:
  Serial.println("Creating example.txt...");
  myFile = SD.open("flight.txt", FILE_WRITE);
  myFile.close();
  myFile = SD.open("flight.txt", FILE_WRITE);            //file created and opened for writing

  if (myFile) {                                         //file has really been opened
    myFile.print("\r\n");
    myFile.print("Date");
    myFile.print(" , ");
    myFile.print("Time");
    myFile.print(" , ");
    myFile.println("Temp");
  }
  myFile.close();

}

char Time[]     = "  :  :  ";
char Calendar[] = "  /  /20  ";
char temperature[] = " 00.00";
char temperature_msb;
byte i, second, minute, hour, day, date, month, year, temperature_lsb;

void display_day() {
  switch (day) {
    case 1:  draw_text(0, 0, " SUNDAY  ", 1); break;
    case 2:  draw_text(0, 0, " MONDAY  ", 1); break;
    case 3:  draw_text(0, 0, " TUESDAY ", 1); break;
    case 4:  draw_text(0, 0, "WEDNESDAY", 1); break;
    case 5:  draw_text(0, 0, "THURSDAY ", 1); break;
    case 6:  draw_text(0, 0, " FRIDAY  ", 1); break;
    default: draw_text(0, 0, "SATURDAY ", 1);
  }
}

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[9] = year   % 10 + 48;
  Calendar[8] = year   / 10 + 48;
  Calendar[4] = month  % 10 + 48;
  Calendar[3] = month  / 10 + 48;
  Calendar[1] = date   % 10 + 48;
  Calendar[0] = date   / 10 + 48;
  if (temperature_msb < 0) {
    temperature_msb = abs(temperature_msb);
    temperature[0] = '-';
  }
  else
    temperature[0] = ' ';
  temperature_lsb >>= 6;
  temperature[2] = temperature_msb % 10  + 48;
  temperature[1] = temperature_msb / 10  + 48;
  if (temperature_lsb == 0 || temperature_lsb == 2) {
    temperature[5] = '0';
    if (temperature_lsb == 0) temperature[4] = '0';
    else                     temperature[4] = '5';
  }
  if (temperature_lsb == 1 || temperature_lsb == 3) {
    temperature[5] = '5';
    if (temperature_lsb == 1) temperature[4] = '2';
    else                     temperature[4] = '7';
  }

  draw_text(60,  0, Calendar, 1);                     // Display the date (format: dd/mm/yyyy)
  draw_text(10, 24, Time, 2);                         // Display the time
  draw_text(75, 55, temperature, 1);                  // Display the temperature
}

void blink_parameter() {
  byte j = 0;
  while (j < 10 && digitalRead(button1) && digitalRead(button2)) {
    j++;
    delay(25);
  }
}

byte edit(byte x_pos, byte y_pos, byte parameter) {
  char text[3];
  sprintf(text, "%02u", parameter);
  while (!digitalRead(button1));                     // Wait until button B1 released
  while (true) {
    while (!digitalRead(button2)) {                  // If button B2 is pressed
      parameter++;
      if (i == 0 && parameter > 31)                  // If date > 31 ==> date = 1
        parameter = 1;
      if (i == 1 && parameter > 12)                  // If month > 12 ==> month = 1
        parameter = 1;
      if (i == 2 && parameter > 99)                  // If year > 99 ==> year = 0
        parameter = 0;
      if (i == 3 && parameter > 23)                  // If hours > 23 ==> hours = 0
        parameter = 0;
      if (i == 4 && parameter > 59)                  // If minutes > 59 ==> minutes = 0
        parameter = 0;
      sprintf(text, "%02u", parameter);
      draw_text(x_pos, y_pos, text, 1);
      delay(200);                                    // Wait 200ms
    }
    draw_text(x_pos, y_pos, "  ", 1);
    blink_parameter();
    draw_text(x_pos, y_pos, text, 1);
    blink_parameter();
    if (!digitalRead(button1)) {                     // If button B1 is pressed
      i++;                                           // Increament 'i' for the next parameter
      return parameter;                              // Return parameter value and exit
    }
  }
}

void draw_text(byte x_pos, byte y_pos, char *text, byte text_size) {
  display.setCursor(x_pos, y_pos);
  display.setTextSize(text_size);
  display.print(text);
  display.display();
}


void blinkLED() {
  unsigned long LEDcurrentMillis = millis();

  if (LEDcurrentMillis - LEDpreviousMillis >= LEDinterval) {
    // save the last time you blinked the LED
    LEDpreviousMillis = LEDcurrentMillis;

    // if the LED is off turn it on and vice-versa:
    if (ledState == LOW) {
      ledState = HIGH;
    } else {
      ledState = LOW;
    }

    // set the LED with the ledState of the variable:
    digitalWrite(ledPin1, ledState);
    digitalWrite(ledPin2, ledState);
  }
}

void settime() {
  i = 0;
  while (!digitalRead(button1));                   // Wait for button B1 release
  while (true) {
    while (!digitalRead(button2)) {                // While button B2 pressed
      day++;                                       // Increment day
      if (day > 7) day = 1;
      display_day();                               // Call display_day function
      delay(200);                                  // Wait 200 ms
    }
    draw_text(0, 0, "         ", 1);
    blink_parameter();                             // Call blink_parameter function
    display_day();                                 // Call display_day function
    blink_parameter();                             // Call blink_parameter function
    if (!digitalRead(button1))                     // If button B1 is pressed
      break;
  }
  //set position of text when editing on button press
  date   = edit(60, 0, date);                      // Edit date
  month  = edit(80, 0, month);                    // Edit month
  year   = edit(110, 0, year);                   // Edit year
  hour   = edit(14, 9, hour);                     // Edit hours
  minute = edit(50, 9, minute);                   // Edit minutes

  // 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 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);                                 // Wait 200ms
}

void displayoled() {
  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
  Wire.beginTransmission(0x68);                 // Start I2C protocol with DS3231 address
  Wire.write(0x11);                             // Send register address
  Wire.endTransmission(false);                  // I2C restart
  Wire.requestFrom(0x68, 2);                    // Request 2 bytes from DS3231 and release I2C bus at end of reading
  temperature_msb = Wire.read();                // Read temperature MSB
  temperature_lsb = Wire.read();                // Read temperature LSB

  display_day();
  DS3231_display();

  delay(50);
}

void loop() {
  if (!digitalRead(button1)) {
    settime();
  }
  writeToSD();    //record data on SD card
  blinkLED();
  displayoled();
}

//===================================================

void writeToSD() {                         //records temperature data of LM35 sensor at 2-min interval (this is an example)
  unsigned long SDcurrentMillis = millis();

  if (SDcurrentMillis - SDpreviousMillis >= SDinterval) {
    // save the last time you blinked the LED
    SDpreviousMillis = SDcurrentMillis;
    myFile = SD.open("flight.txt", FILE_WRITE);
    if (myFile) {
      float myTemp = rtc.getTemperature();
      DateTime nowDT = rtc.now();
      myFile.print("\r\n");
      myFile.print(nowDT.day(), DEC); myFile.print('/');
      myFile.print(nowDT.month(), DEC); myFile.print('/');
      myFile.print(nowDT.year(), DEC); myFile.print(" , ");
      myFile.print(nowDT.hour(), DEC); myFile.print(':');
      myFile.print(nowDT.minute(), DEC); myFile.print(':');
      myFile.print(nowDT.second(), DEC); myFile.print(" , ");
      myFile.print(myTemp, 2);
      myFile.close();
      Serial.println("temperature updated");
    }
  }
}
[/code]

Hi,
Good that you have it functioning.

What controller did you end up using?

Tom... :smiley: :+1: :coffee: :australia:

I used the Mega 2560. Might not be the end all for this project as I am adding more functionality. Might end up using a Teensy board but we will see when I add the next part of the project. I am taking it in steps though, and have learned a ton. The best part is that I learned how to program in pockets of code and to make sure each pocket worked before putting the whole thing into run mode. That helped me diagnose exactly what I did wrong. Also, I came to understand using the interval instead of delay to keep a time for things. I will end up modding this code to fully incorporate that aspect but as it sits the code works great!