Components

	Arduino Nano R3	x 1
	DS3231SN# Analog Devices Inc./Maxim Integrated	x 1
	8x32 MAX7219 Led matrix module	x 1
	Pushbutton Switch	x 2

Tools, APP Software Used etc.

	arduino IDE Arduino
	Soldering Iron Kit

Description

DIY Arduino Holographic Matrix Clock

This is another in my series of unusual DIY clocks, this time realized based on the holographic effect.It's really very interesting to watch, and you get the impression that the numbers are floating in the air.

Otherwise, this is the simplest way of creating a hologram, where the light source and the screen are placed at an angle of 45 degrees. In case when we have a text or a numerical message, we need to know that the information of the light source should be a mirror of the original image which we should see on the screen.

For the light source I use a very simple to build matrix clock, which is actually a modified version of one of my previous projects entitled "Arduino Nano mini LED matrix clock" , where I modified the original code to get a mirrored image.

As I mentioned the clock is really simple to build, and consists of several components:

- Arduino nano microcontroller

- DS3231 Realtime clock module

- 8x32 Led matrix module

- and two buttons

If you want to make a PCB for this project, or for any other electronic project, PCBway (www.pcbway.com) is a great choice for you. PCBway is one of the most experienced PCB manufacturing company in China in field of PCB prototype and fabrication. They provide completed PCB assembly service with worldwide free shipping , and ISO9001 quality control system. Also, on their site there is an online gerber viewer where you can upload your gerber and drill files to render your board.

This little clock is full of different faces, work modes, and other options that you will be able to see in the continuation of the video.

As for the mechanical construction of the device, it is necessary to observe several rules:

- The primary light source should be positioned so that it cannot be seen from the front of the device.

- The screen should be placed at an angle of 45 degrees with respect to the plane of the light source.

- Also, The screen should be as thin as possible, but also strong enough to keep its shape. If ordinary glass with a thickness of 3 or 4 mm is used, the light will be refracted twice, so the image will be blurred.

- The entire device should be covered with black matte wallpaper or paint, in order to have as little reflected light as possible on the surrounding parts, for a more realistic appearance.

- By changing the distance between the source and the screen, the height of the hologram image changes, so we have to determine this distance experimentally.

If the source and screen are set according to the recommendations given above, the hologram image appears in the middle of the screen. With two buttons we can adjust the various options.

I adapted this device from the beginning so that it can also displays holograms from a smartphone. For this purpose, the light of the smartphone should be set to maximum, and then a video specially designed for the hologram presentation should be selected. These videos are usually with a black background, so that the hologram effect is more emphasized.

Code

Arduino code

C/C++

/***********************************************************************

Mini Clock v1.0, Jul 2014 by Nick Hall
Distributed under the terms of the GPL.

For help on how to build the clock see my blog:
http://123led.wordpress.com/

Tested on IDE v1.6.5 

modified by Mirko Pavleski May 2023

***********************************************************************/

//include libraries:
#include "LedControl.h"
#include <FontLEDClock.h>                // Font library
#include <Wire.h>                        // DS1307 clock
#include "RTClib.h"                      // DS1307 clock
#include <Button.h>                      // Button library by Alexander Brevig


// Setup LED Matrix

// pin 10 is connected to the DataIn on the display
// pin 12 is connected to the CLK on the display
// pin 11 is connected to LOAD on the display(cs)
LedControl lc = LedControl(10, 12, 11, 4); //sets the 3 pins as 12, 11 & 10 and then sets 4 displays (max is 8 displays)

//global variables
byte intensity = 7;                      // Default intensity/brightness (0-15)
byte clock_mode = 0;                     // Default clock mode. Default = 0 (basic_mode)
bool random_mode = 0;                    // Define random mode - changes the display type every few hours. Default = 0 (off)
byte old_mode = clock_mode;              // Stores the previous clock mode, so if we go to date or whatever, we know what mode to go back to after.
bool ampm = 0;                           // Define 12 or 24 hour time. 0 = 24 hour. 1 = 12 hour
byte change_mode_time = 0;               // Holds hour when clock mode will next change if in random mode.
unsigned long delaytime = 500;           // We always wait a bit between updates of the display
int rtc[7];                              // Holds real time clock output



char days[7][4] = {
  "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
}; //day array - used in slide, basic_mode and jumble modes (The DS1307 outputs 1-7 values for day of week)
char daysfull[7][9] = {
  "Sunday", "Monday", "Tuesday", "Wed", "Thursday", "Friday", "Saturday"
};
char suffix[4][3] = {
  "st", "nd", "rd", "th"
};  //date suffix array, used in slide, basic_mode and jumble modes. e,g, 1st 2nd ...

//define constants
#define NUM_DISPLAY_MODES 3              // Number display modes (conting zero as the first mode)
#define NUM_SETTINGS_MODES 4             // Number settings modes = 6 (conting zero as the first mode)
#define SLIDE_DELAY 20                   // The time in milliseconds for the slide effect per character in slide mode. Make this higher for a slower effect
#define cls          clear_display       // Clear display

RTC_DS1307 ds1307;                              // Create RTC object

Button buttonA = Button(2, BUTTON_PULLUP);      // Setup button A (using button library)
Button buttonB = Button(3, BUTTON_PULLUP);      // Setup button B (using button library)

void setup() {

  digitalWrite(2, HIGH);                 // turn on pullup resistor for button on pin 2
  digitalWrite(3, HIGH);                 // turn on pullup resistor for button on pin 3
  digitalWrite(4, HIGH);                 // turn on pullup resistor for button on pin 4
  
  Serial.begin(9600); //start serial

  //initialize the 4 matrix panels
  //we have already set the number of devices when we created the LedControl
  int devices = lc.getDeviceCount();
  //we have to init all devices in a loop
  for (int address = 0; address < devices; address++) {
    /*The MAX72XX is in power-saving mode on startup*/
    lc.shutdown(address, false);
    /* Set the brightness to a medium values */
    lc.setIntensity(address, intensity);
    /* and clear the display */
    lc.clearDisplay(address);
  }

  //Setup DS1307 RTC
#ifdef AVR
  Wire.begin();
#else
  Wire1.begin(); // Shield I2C pins connect to alt I2C bus on Arduino
#endif
  ds1307.begin(); //start RTC Clock

  if (! ds1307.isrunning()) {
    Serial.println("RTC is NOT running!");
    ds1307.adjust(DateTime(__DATE__, __TIME__));  // sets the RTC to the date & time this sketch was compiled
  }
  //Show software version & hello message
  printver();
  
  //enable red led
  digitalWrite(13, HIGH);
}

void loop() {
  
  //run the clock with whatever mode is set by clock_mode - the default is set at top of code.
  switch (clock_mode){
        
  case 0: 
    basic_mode();
    break; 
  case 1: 
   small_mode(); 
    break;
  case 2: 
    slide(); 
    break;
  case 3: 
    word_clock(); 
    break;
  case 4: 
    setup_menu(); 
    break;
  }
}


//plot a point on the display
void plot (byte x, byte y, byte val) {

  //select which matrix depending on the x coord
  byte address;
  if (x >= 0 && x <= 7)   {
    address = 3;
  }
  if (x >= 8 && x <= 15)  {
    address = 2;
    x = x - 8;
  }
  if (x >= 16 && x <= 23) {
    address = 1;
    x = x - 16;
  }
  if (x >= 24 && x <= 31) {
    address = 0;
    x = x - 24;
  }

  if (val == 1) {
   // lc.setLed(address, y, x, true);
   lc.setLed(address, 7-y, x, true);
  } else {
  //  lc.setLed(address, y, x, false);
  lc.setLed(address, 7-y, x, false);
  }
}


//clear screen
void clear_display() {
  for (byte address = 0; address < 4; address++) {
    lc.clearDisplay(address);
  }
}

//fade screen down
void fade_down() {

  //fade from global intensity to 1
  for (byte i = intensity; i > 0; i--) {
    for (byte address = 0; address < 4; address++) {
      lc.setIntensity(address, i);
    }
    delay(30); //change this to change fade down speed
  }

  clear_display(); //clear display completely (off)

  //reset intentsity to global val
  for (byte address = 0; address < 4; address++) {
    lc.setIntensity(address, intensity);
  }
}



//power up led test & display software version number
void printver() {

  byte i = 0;
  char ver_a[9] = "Vers 1.0";
  char ver_b[9] = " Hello! ";

  //test all leds.
  for (byte x = 0; x <= 31; x++) {
    for (byte y = 0; y <= 7; y++) {
      plot(x, y, 1);
    }
  }
  delay(500);
  fade_down();

  while (ver_a[i]) {
    puttinychar((i * 4), 1, ver_a[i]);
    delay(35);
    i++;
  }
  delay(700);
  fade_down();
  i = 0;
  while (ver_b[i]) {
    puttinychar((i * 4), 1, ver_b[i]);
    delay(35);
    i++;
  }
  delay(700);
  fade_down();
}


// puttinychar
// Copy a 3x5 character glyph from the myfont data structure to display memory, with its upper left at the given coordinate
// This is unoptimized and simply uses plot() to draw each dot.
void puttinychar(byte x, byte y, char c)
{
  byte dots;
  if (c >= 'A' && c <= 'Z' || (c >= 'a' && c <= 'z') ) {
    c &= 0x1F;   // A-Z maps to 1-26
  }
  else if (c >= '0' && c <= '9') {
    c = (c - '0') + 32;
  }
  else if (c == ' ') {
    c = 0; // space
  }
  else if (c == '.') {
    c = 27; // full stop
  }
  else if (c == ':') {
    c = 28; // colon
  }
  else if (c == '\'') {
    c = 29; // single quote mark
  }
  else if (c == '!') {
    c = 30; // single quote mark
  }
  else if (c == '?') {
    c = 31; // single quote mark
  }

  for (byte col = 0; col < 3; col++) {
    dots = pgm_read_byte_near(&mytinyfont[c][col]);
    for (char row = 0; row < 5; row++) {
      if (dots & (16 >> row))
        plot(x + col, y + row, 1);
      else
        plot(x + col, y + row, 0);
    }
  }
}



void putnormalchar(byte x, byte y, char c)
{

  byte dots;
  //  if (c >= 'A' && c <= 'Z' || (c >= 'a' && c <= 'z') ) {
  //    c &= 0x1F;   // A-Z maps to 1-26
  //  }
  if (c >= 'A' && c <= 'Z' ) {
    c &= 0x1F;   // A-Z maps to 1-26
  }
  else if (c >= 'a' && c <= 'z') {
    c = (c - 'a') + 41;   // A-Z maps to 41-67
  }
  else if (c >= '0' && c <= '9') {
    c = (c - '0') + 31;
  }
  else if (c == ' ') {
    c = 0; // space
  }
  else if (c == '.') {
    c = 27; // full stop
  }
  else if (c == '\'') {
    c = 28; // single quote mark
  }
  else if (c == ':') {
    c = 29; // clock_mode selector arrow
  }
  else if (c == '>') {
    c = 30; // clock_mode selector arrow
  }
  else if (c >= -80 && c <= -67) {
    c *= -1;
  }

  for (char col = 0; col < 5; col++) {
    dots = pgm_read_byte_near(&myfont[c][col]);
    for (char row = 0; row < 7; row++) {
      //check coords are on screen before trying to plot
      //if ((x >= 0) && (x <= 31) && (y >= 0) && (y <= 7)){

      if (dots & (64 >> row)) {   // only 7 rows.
        plot(x + col, y + row, 1);
      } else {
        plot(x + col, y + row, 0);
      }
      //}
    }
  }
}

//small_mode
//show the time in small 3x5 characters with seconds display

void small_mode() {

  char textchar[8]; // the 16 characters on the display
  byte mins = 100; //mins
  byte secs = rtc[0]; //seconds
  byte old_secs = secs; //holds old seconds value - from last time seconds were updated o display - used to check if seconds have changed
  
  cls();

  //run clock main loop as long as run_mode returns true
  while (run_mode()) {

    get_time();
  
    //check for button press
    if (buttonA.uniquePress()) {
      switch_mode();
      return;
    }
    if (buttonB.uniquePress()) {
      display_date();
      return;
    }
    
    //if secs changed then update them on the display
    secs = rtc[0];
    if (secs != old_secs) {

      //secs
      char buffer[3];
      itoa(secs, buffer, 10);

      //fix - as otherwise if num has leading zero, e.g. "03" secs, itoa coverts this to chars with space "3 ".
      if (secs < 10) {
        buffer[1] = buffer[0];
        buffer[0] = '0';
      }

      puttinychar( 20, 1, ':'); //seconds colon
      puttinychar( 24, 1, buffer[0]); //seconds
      puttinychar( 28, 1, buffer[1]); //seconds
      old_secs = secs;
    }

    //if minute changes change time
    if (mins != rtc[1]) {

      //reset these for comparison next time
      mins = rtc[1];
      byte hours = rtc[2];
      if (hours > 12) {
        hours = hours - ampm * 12;
      }
      if (hours < 1) {
        hours = hours + ampm * 12;
      }


      //byte dow  = rtc[3]; // the DS1307 outputs 0 - 6 where 0 = Sunday0 - 6 where 0 = Sunday.
      //byte date = rtc[4];

      //set characters
      char buffer[3];
      itoa(hours, buffer, 10);

      //fix - as otherwise if num has leading zero, e.g. "03" hours, itoa coverts this to chars with space "3 ".
      if (hours < 10) {
        buffer[1] = buffer[0];
        //if we are in 12 hour mode blank the leading zero.
        if (ampm) {
          buffer[0] = ' ';
        }
        else {
          buffer[0] = '0';
        }
      }
      //set hours chars
      textchar[0] = buffer[0];
      textchar[1] = buffer[1];
      textchar[2] = ':';

      itoa (mins, buffer, 10);
      if (mins < 10) {
        buffer[1] = buffer[0];
        buffer[0] = '0';
      }
      //set mins characters
      textchar[3] = buffer[0];
      textchar[4] = buffer[1];

      //do seconds
      textchar[5] = ':';
      buffer[3];
      secs = rtc[0];
      itoa(secs, buffer, 10);

      //fix - as otherwise if num has leading zero, e.g. "03" secs, itoa coverts this to chars with space "3 ".
      if (secs < 10) {
        buffer[1] = buffer[0];
        buffer[0] = '0';
      }
      //set seconds
      textchar[6] = buffer[0];
      textchar[7] = buffer[1];

      byte x = 0;
      byte y = 0;

      //print each char
      for (byte x = 0; x < 6 ; x++) {
        puttinychar( x * 4, 1, textchar[x]);
      }
    }
    delay(50);
  }
  fade_down();
}


// basic_mode()
// show the time in 5x7 characters
void basic_mode()
{
  cls();

  char buffer[3];   //for int to char conversion to turn rtc values into chars we can print on screen
  byte offset = 0;  //used to offset the x postition of the digits and centre the display when we are in 12 hour mode and the clock shows only 3 digits. e.g. 3:21
  byte x, y;        //used to draw a clear box over the left hand "1" of the display when we roll from 12:59 -> 1:00am in 12 hour mode.

  //do 12/24 hour conversion if ampm set to 1
  byte hours = rtc[2];

  if (hours > 12) {
    hours = hours - ampm * 12;
  }
  if (hours < 1) {
    hours = hours + ampm * 12;
  }

  //do offset conversion
  if (ampm && hours < 10) {
    offset = 2;
  }
  
  //set the next minute we show the date at
  //set_next_date();
  
  // initially set mins to value 100 - so it wll never equal rtc[1] on the first loop of the clock, meaning we draw the clock display when we enter the function
  byte secs = 100;
  byte mins = 100;
  int count = 0;
  
  //run clock main loop as long as run_mode returns true
  while (run_mode()) {

    //get the time from the clock chip
    get_time();
    
    //check for button press
    if (buttonA.uniquePress()) {
      switch_mode();
      return;
    }
    if (buttonB.uniquePress()) {
      display_date();
      return;
    }

    //check whether it's time to automatically display the date
    //check_show_date();

    //draw the flashing : as on if the secs have changed.
    if (secs != rtc[0]) {

      //update secs with new value
      secs = rtc[0];

      //draw :
      plot (15 - offset, 2, 1); //top point
      plot (15 - offset, 5, 1); //bottom point
      count = 400;
    }

    //if count has run out, turn off the :
    if (count == 0) {
      plot (15 - offset, 2, 0); //top point
      plot (15 - offset, 5, 0); //bottom point
    }
    else {
      count--;
    }

    //re draw the display if button pressed or if mins != rtc[1] i.e. if the time has changed from what we had stored in mins, (also trigggered on first entering function when mins is 100)
    if (mins != rtc[1]) {

      //update mins and hours with the new values
      mins = rtc[1];
      hours = rtc[2];

      //adjust hours of ampm set to 12 hour mode
      if (hours > 12) {
        hours = hours - ampm * 12;
      }
      if (hours < 1) {
        hours = hours + ampm * 12;
      }

      itoa(hours, buffer, 10);

      //if hours < 10 the num e.g. "3" hours, itoa coverts this to chars with space "3 " which we dont want
      if (hours < 10) {
        buffer[1] = buffer[0];
        buffer[0] = '0';
      }

      //print hours
      //if we in 12 hour mode and hours < 10, then don't print the leading zero, and set the offset so we centre the display with 3 digits.
      if (ampm && hours < 10) {
        offset = 2;

        //if the time is 1:00am clear the entire display as the offset changes at this time and we need to blank out the old 12:59
        if ((hours == 1 && mins == 0) ) {
          cls();
        }
      }
      else {
        //else no offset and print hours tens digit
        offset = 0;

        //if the time is 10:00am clear the entire display as the offset changes at this time and we need to blank out the old 9:59
        if (hours == 10 && mins == 0) {
          cls();
        }


        putnormalchar(1,  0, buffer[0]);
      }
      //print hours ones digit
      putnormalchar(7 - offset, 0, buffer[1]);


      //print mins
      //add leading zero if mins < 10
      itoa (mins, buffer, 10);
      if (mins < 10) {
        buffer[1] = buffer[0];
        buffer[0] = '0';
      }
      //print mins tens and ones digits
      putnormalchar(19 - offset, 0, buffer[0]);
      putnormalchar(25 - offset, 0, buffer[1]);
    }
  }
  fade_down();
}


//like basic_mode but with slide effect
void slide() {

  byte digits_old[4] = {99, 99, 99, 99}; //old values  we store time in. Set to somthing that will never match the time initially so all digits get drawn wnen the mode starts
  byte digits_new[4]; //new digits time will slide to reveal
  byte digits_x_pos[4] = {25, 19, 7, 1}; //x pos for which to draw each digit at

  char old_char[2]; //used when we use itoa to transpose the current digit (type byte) into a char to pass to the animation function
  char new_char[2]; //used when we use itoa to transpose the new digit (type byte) into a char to pass to the animation function

  //old_chars - stores the 5 day and date suffix chars on the display. e.g. "mon" and "st". We feed these into the slide animation as the current char when these chars are updated.
  //We sent them as A initially, which are used when the clocl enters the mode and no last chars are stored.
  //char old_chars[6] = "AAAAA";

  //plot the clock colon on the display
  cls();
  putnormalchar( 13, 0, ':');

  byte old_secs = rtc[0]; //store seconds in old_secs. We compare secs and old secs. WHen they are different we redraw the display

  //run clock main loop as long as run_mode returns true
  while (run_mode()) {

    get_time();
    
    //check for button press
    if (buttonA.uniquePress()) {
      switch_mode();
      return;
    }
      if (buttonB.uniquePress()) {
      display_date();
      return;
    }

    //if secs have changed then update the display
    if (rtc[0] != old_secs) {
      old_secs = rtc[0];

      //do 12/24 hour conversion if ampm set to 1
      byte hours = rtc[2];
      if (hours > 12) {
        hours = hours - ampm * 12;
      }
      if (hours < 1) {
        hours = hours + ampm * 12;
      }

      //split all date and time into individual digits - stick in digits_new array

      //rtc[0] = secs                        //array pos and digit stored
      //digits_new[0] = (rtc[0]%10);           //0 - secs ones
      //digits_new[1] = ((rtc[0]/10)%10);      //1 - secs tens
      //rtc[1] = mins
      digits_new[0] = (rtc[1] % 10);         //2 - mins ones
      digits_new[1] = ((rtc[1] / 10) % 10);  //3 - mins tens
      //rtc[2] = hours
      digits_new[2] = (hours % 10);         //4 - hour ones
      digits_new[3] = ((hours / 10) % 10);  //5 - hour tens
      //rtc[4] = date
      //digits_new[6] = (rtc[4]%10);           //6 - date ones
      //digits_new[7] = ((rtc[4]/10)%10);      //7 - date tens

      //draw initial screen of all chars. After this we just draw the changes.

      //compare digits 0 to 3 (mins and hours)
      for (byte i = 0; i <= 3; i++) {
        //see if digit has changed...
        if (digits_old[i] != digits_new[i]) {

          //run 9 step animation sequence for each in turn
          for (byte seq = 0; seq <= 8 ; seq++) {

            //convert digit to string
            itoa(digits_old[i], old_char, 10);
            itoa(digits_new[i], new_char, 10);

            //if set to 12 hour mode and we're on digit 2 (hours tens mode) then check to see if this is a zero. If it is, blank it instead so we get 2.00pm not 02.00pm
            if (ampm && i == 3) {
              if (digits_new[3] == 0) {
                new_char[0] = ' ';
              }
              if (digits_old[3] == 0) {
                old_char[0] = ' ';
              }
            }
            //draw the animation frame for each digit
            slideanim(digits_x_pos[i], 0, seq, old_char[0], new_char[0]);
            delay(SLIDE_DELAY);
          }
        }
      }

      /*
      //compare date digit 6 (ones) and (7) tens - if either of these change we need to update the date line. We compare date tens as say from Jan 31 -> Feb 01 then ones digit doesn't change
      if ((digits_old[6] != digits_new[6]) || (digits_old[7] != digits_new[7])) {
        //change the day shown. Loop below goes through each of the 3 chars in turn e.g. "MON"
        for (byte day_char = 0; day_char <=2 ; day_char++){
          //run the anim sequence for each char
          for (byte seq = 0; seq <=8 ; seq++){
            //the day (0 - 6) Read this number into the days char array. the seconds number in the array 0-2 gets the 3 chars of the day name, e.g. m o n
            slideanim(6*day_char,8,seq,old_chars[day_char],days[rtc[3]][day_char]); //6 x day_char gives us the x pos for the char
            delay(SLIDE_DELAY);
          }
          //save the old day chars into the old_chars array at array pos 0-2. We use this next time we change the day and feed it to the animation as the current char. The updated char is fed in as the new char.
          old_chars[day_char] = days[rtc[3]][day_char];
        }

        //change the date tens digit (if needed) and ones digit. (the date ones digit wil alwaus change, but putting this in the 'if' loop makes it a bit neater code wise.)
        for (byte i = 7; i >= 6; i--){
          if (digits_old[i] != digits_new[i]) {
            for (byte seq = 0; seq <=8 ; seq++){
              itoa(digits_old[i],old_char,10);
              itoa(digits_new[i],new_char,10);
              slideanim(digits_x_pos[i],8,seq,old_char[0],new_char[0]);
              delay(SLIDE_DELAY);
            }
          }
        }

        //print the day suffix "nd" "rd" "th" etc. First work out date 2 letter suffix - eg st, nd, rd, th
        byte s = 3; //the pos to read our suffix array from.
        byte date = rtc[4];
        if(date == 1 || date == 21 || date == 31) {
          s = 0;
        }
        else if (date == 2 || date == 22) {
          s = 1;
        }
        else if (date == 3 || date == 23) {
          s = 2;
        }

        for (byte suffix_char = 0; suffix_char <=1 ; suffix_char++){
          for (byte seq = 0; seq <=8 ; seq++){
            slideanim((suffix_char*6)+36,8,seq,old_chars[suffix_char+3],suffix[s][suffix_char]); // we pass in the old_char array char as the current char and the suffix array as the new char
            delay(SLIDE_DELAY);
          }
          //save the suffic char in the old chars array at array pos 3 and 5.  We use these chars next time we change the suffix and feed it to the animation as the current char. The updated char is fed in as the new char.
          old_chars[suffix_char+3] = suffix[s][suffix_char];
        }
      }//end do date line
      */


      //save digita array tol old for comparison next loop
      for (byte i = 0; i <= 3; i++) {
        digits_old[i] =  digits_new[i];
      }
    }//secs/oldsecs
  }//while loop
  fade_down();
}


//called by slide
//this draws the animation of one char sliding on and the other sliding off. There are 8 steps in the animation, we call the function to draw one of the steps from 0-7
//inputs are are char x and y, animation frame sequence (0-7) and the current and new chars being drawn.
void slideanim(byte x, byte y, byte sequence, char current_c, char new_c) {

  //  To slide one char off and another on we need 9 steps or frames in sequence...

  //  seq# 0123456 <-rows of the display
  //   |   |||||||
  //  seq0 0123456  START - all rows of the display 0-6 show the current characters rows 0-6
  //  seq1  012345  current char moves down one row on the display. We only see it's rows 0-5. There are at display positions 1-6 There is a blank row inserted at the top
  //  seq2 6 01234  current char moves down 2 rows. we now only see rows 0-4 at display rows 2-6 on the display. Row 1 of the display is blank. Row 0 shows row 6 of the new char
  //  seq3 56 0123
  //  seq4 456 012  half old / half new char
  //  seq5 3456 01
  //  seq6 23456 0
  //  seq7 123456
  //  seq8 0123456  END - all rows show the new char

  //from above we can see...
  //currentchar runs 0-6 then 0-5 then 0-4 all the way to 0. starting Y position increases by 1 row each time.
  //new char runs 6 then 5-6 then 4-6 then 3-6. starting Y position increases by 1 row each time.

  //if sequence number is below 7, we need to draw the current char
  if (sequence < 7) {
    byte dots;
    // if (current_c >= 'A' &&  || (current_c >= 'a' && current_c <= 'z') ) {
    //   current_c &= 0x1F;   // A-Z maps to 1-26
    // }
    if (current_c >= 'A' && current_c <= 'Z' ) {
      current_c &= 0x1F;   // A-Z maps to 1-26
    }
    else if (current_c >= 'a' && current_c <= 'z') {
      current_c = (current_c - 'a') + 41;   // A-Z maps to 41-67
    }
    else if (current_c >= '0' && current_c <= '9') {
      current_c = (current_c - '0') + 31;
    }
    else if (current_c == ' ') {
      current_c = 0; // space
    }
    else if (current_c == '.') {
      current_c = 27; // full stop
    }
    else if (current_c == '\'') {
      current_c = 28; // single quote mark
    }
    else if (current_c == ':') {
      current_c = 29; //colon
    }
    else if (current_c == '>') {
      current_c = 30; // clock_mode selector arrow
    }

    byte curr_char_row_max = 7 - sequence; //the maximum number of rows to draw is 6 - sequence number
    byte start_y = sequence; //y position to start at - is same as sequence number. We inc this each loop

    //plot each row up to row maximum (calculated from sequence number)
    for (byte curr_char_row = 0; curr_char_row <= curr_char_row_max; curr_char_row++) {
      for (byte col = 0; col < 5; col++) {
        dots = pgm_read_byte_near(&myfont[current_c][col]);
        if (dots & (64 >> curr_char_row))
          plot(x + col, y + start_y, 1); //plot led on
        else
          plot(x + col, y + start_y, 0); //else plot led off
      }
      start_y++;//add one to y so we draw next row one down
    }
  }

  //draw a blank line between the characters if sequence is between 1 and 7. If we don't do this we get the remnants of the current chars last position left on the display
  if (sequence >= 1 && sequence <= 8) {
    for (byte col = 0; col < 5; col++) {
      plot(x + col, y + (sequence - 1), 0); //the y position to draw the line is equivalent to the sequence number - 1
    }
  }



  //if sequence is above 2, we also need to start drawing the new char
  if (sequence >= 2) {

    //work out char
    byte dots;
    //if (new_c >= 'A' && new_c <= 'Z' || (new_c >= 'a' && new_c <= 'z') ) {
    //  new_c &= 0x1F;   // A-Z maps to 1-26
    //}
    if (new_c >= 'A' && new_c <= 'Z' ) {
      new_c &= 0x1F;   // A-Z maps to 1-26
    }
    else if (new_c >= 'a' && new_c <= 'z') {
      new_c = (new_c - 'a') + 41;   // A-Z maps to 41-67
    }
    else if (new_c >= '0' && new_c <= '9') {
      new_c = (new_c - '0') + 31;
    }
    else if (new_c == ' ') {
      new_c = 0; // space
    }
    else if (new_c == '.') {
      new_c = 27; // full stop
    }
    else if (new_c == '\'') {
      new_c = 28; // single quote mark
    }
    else if (new_c == ':') {
      new_c = 29; // clock_mode selector arrow
    }
    else if (new_c == '>') {
      new_c = 30; // clock_mode selector arrow
    }

    byte newcharrowmin = 6 - (sequence - 2); //minimumm row num to draw for new char - this generates an output of 6 to 0 when fed sequence numbers 2-8. This is the minimum row to draw for the new char
    byte start_y = 0; //y position to start at - is same as sequence number. we inc it each row

    //plot each row up from row minimum (calculated by sequence number) up to 6
    for (byte newcharrow = newcharrowmin; newcharrow <= 6; newcharrow++) {
      for (byte col = 0; col < 5; col++) {
        dots = pgm_read_byte_near(&myfont[new_c][col]);
        if (dots & (64 >> newcharrow))
          plot(x + col, y + start_y, 1); //plot led on
        else
          plot(x + col, y + start_y, 0); //else plot led off
      }
      start_y++;//add one to y so we draw next row one down
    }
  }
}



//print a clock using words rather than numbers
void word_clock() {

  cls();

  char numbers[19][10]   = {
    "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten",
    "eleven", "twelve", "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "nineteen"
  };
  char numberstens[5][7] = {
    "ten", "twenty", "thirty", "forty", "fifty"
  };
  
  //potentially 3 lines to display
  char str_a[8];
  char str_b[8];
  char str_c[8];

  //byte hours_y, mins_y; //hours and mins and positions for hours and mins lines

  byte hours = rtc[2];
  if (hours > 12) {
    hours = hours - ampm * 12;
  }
  if (hours < 1) {
    hours = hours + ampm * 12;
  }

  get_time(); //get the time from the clock chip
  byte old_mins = 100; //store mins in old_mins. We compare mins and old mins & when they are different we redraw the display. Set this to 100 initially so display is drawn when mode starts.
  byte mins;

  //run clock main loop as long as run_mode returns true
  while (run_mode()) {
    
    //check for button press
    if (buttonA.uniquePress()) {
      switch_mode();
      return;
    }
    if (buttonB.uniquePress()) {
      display_date();
    }

    get_time(); //get the time from the clock chip
    mins = rtc[1];  //get mins


    //if mins is different from old_mins - redraw display
    if (mins != old_mins) {

      //update old_mins with current mins value
      old_mins = mins;

      //reset these for comparison next time
      mins = rtc[1];
      hours = rtc[2];

      //make hours into 12 hour format
      if (hours > 12) {
        hours = hours - 12;
      }
      if (hours == 0) {
        hours = 12;
      }

      //split mins value up into two separate digits
      int minsdigit = rtc[1] % 10;
      byte minsdigitten = (rtc[1] / 10) % 10;

      //if mins <= 10 , then top line has to read "minsdigti past" and bottom line reads hours
      if (mins < 10) {
        strcpy (str_a, numbers[minsdigit - 1]);
        strcpy (str_b, "PAST");
        strcpy (str_c, numbers[hours - 1]);
      }

      //if mins = 10, cant use minsdigit as above, so soecial case to print 10 past /n hour.
      if (mins == 10) {
        strcpy (str_a, numbers[9]);
        strcpy (str_b, " PAST");
        strcpy (str_c, numbers[hours - 1]);
      }

      //if time is not on the hour - i.e. both mins digits are not zero,
      //then make first line read "hours" and 2 & 3rd lines read "minstens"  "mins" e.g. "three /n twenty /n one"
      else if (minsdigitten != 0 && minsdigit != 0  ) {

        strcpy (str_a, numbers[hours - 1]);

        //if mins is in the teens, use teens from the numbers array for the 2nd line, e.g. "fifteen"
        //if (mins >= 11 && mins <= 19) {
        if (mins <= 19) {
          strcpy (str_b, numbers[mins - 1]);
        }
        else {
          strcpy (str_b, numberstens[minsdigitten - 1]);

          strcpy (str_c, numbers[minsdigit - 1]);
        }
      }
      // if mins digit is zero, don't print it. read read "hours" "minstens" e.g. "three /n twenty"
      else if (minsdigitten != 0 && minsdigit == 0  ) {
        strcpy (str_a, numbers[hours - 1]);
        strcpy (str_b, numberstens[minsdigitten - 1]);
        strcpy (str_c, "");
      }

      //if both mins are zero, i.e. it is on the hour, the top line reads "hours" and bottom line reads "o'clock"
      else if (minsdigitten == 0 && minsdigit == 0  ) {
        strcpy (str_a, numbers[hours - 1]);
        strcpy (str_b, "O'CLOCK");
        strcpy (str_c, "");
      }

    }//end worknig out time

    //run in a loop
    //print line a "twelve"
    byte len = 0;
    while (str_a[len]) {
      len++;
    }; //get length of message
    byte offset_top = (31 - ((len - 1) * 4)) / 2; //

    //plot hours line
    byte i = 0;
    while (str_a[i]) {
      puttinychar((i * 4) + offset_top, 1, str_a[i]);
      i++;
    }
    
    //hold display but check for button presses
    int counter = 1000;
    while (counter > 0){
      //check for button press
      if (buttonA.uniquePress()) {
        switch_mode();
        return;
      }
...

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Schematic and Layout

Schematic

Schematic.jpg