// https://www.hackster.io/OriginalCaveman/max7219-conquers-old-school-16-segment-displays-61ba8a
#include "pgmspace.h"
#include "stdlib.h"
const int NUMBER_OF_ELEMENTS = 96;
const int MAX_SIZE = 10;
//Outer Segment Codes
const char OSeg [NUMBER_OF_ELEMENTS] [MAX_SIZE] PROGMEM = {
  {"00000000"},  //
  {"00000000"},  //
  {"00000000"},  //
  {"00000000"},  //
  {"00000000"},  //
  {"00000000"},  //
  {"00000000"},  //
  {"00000000"},  //
  {"00000000"},  //
  {"00000000"},  //
  {"00000000"},  //*
  {"00000000"},  //+
  {"00000000"},  //
  {"00000000"},  //-
  {"00000000"},  //
  {"00000000"},  ///
  {"00111100"},  //0
  {"00011000"},  //1
  {"00110100"},  //2
  {"00111100"},  //3
  {"00011000"},  //4
  {"00101100"},  //5
  {"00101100"},  //6
  {"00111000"},  //7
  {"00111100"},  //8
  {"00111100"},  //9
  {"00000000"},  //
  {"00000000"},  //
  {"00000000"},  //
  {"00000000"},  //
  {"00000000"},  //
  {"00000000"},  //
  {"11110111"},  //@
  {"11111001"},  //A
  {"01111110"},  //B
  {"11100111"},  //C
  {"01111110"},  //D
  {"11100111"},  //E
  {"11100001"},  //F
  {"11101111"},  //G
  {"10011001"},  //H
  {"01100110"},  //I
  {"00011111"},  //J
  {"10000001"},  //K
  {"10000111"},  //L
  {"10011001"},  //M
  {"10011001"},  //N
  {"11111111"},  //O
  {"11110001"},  //P
  {"11111111"},  //Q
  {"11110001"},  //R
  {"11101110"},  //S
  {"01100000"},  //T
  {"10011111"},  //U
  {"10000001"},  //V
  {"10011001"},  //W
  {"00000000"},  //X
  {"10011110"},  //Y
  {"01100110"},  //Z
  {"00100100"},  //[
  {"00000000"},  //\
  {"01000010"},  //]
  {"00000000"},  //^
  {"00000110"},  //_
  {"00000000"},  //`
  {"00000111"},  //a
  {"10000011"},  //b
  {"00000011"},  //c
  {"00000011"},  //d
  {"00000011"},  //e
  {"00100000"},  //f
  {"11000010"},  //g
  {"10000001"},  //h
  {"00000000"},  //i
  {"00000011"},  //j
  {"00000000"},  //k
  {"00000000"},  //l
  {"00001001"},  //m
  {"00000001"},  //n
  {"00000011"},  //o
  {"11000001"},  //p
  {"11000000"},  //q
  {"00000001"},  //r
  {"11000010"},  //s
  {"10000011"},  //t
  {"00000011"},  //u
  {"00000001"},  //v
  {"00001001"},  //w
  {"00000000"},  //x
  {"10000010"},  //y
  {"00000010"},  //z
  {"00100100"},  //{
  {"00000000"},  //|
  {"01000010"},  //}
  {"00000000"},  //~
  {"00000000"},  //
};

// Inner Segment Codes
const char ISeg [NUMBER_OF_ELEMENTS] [MAX_SIZE] PROGMEM = {
  {"00000000"},  //
  {"00000000"},  //
  {"00000000"},  //
  {"00000000"},  //
  {"00000000"},  //
  {"00000000"},  //
  {"00000000"},  //
  {"00000000"},  //
  {"00000000"},  //
  {"00000000"},  //
  {"11111111"},  //*
  {"10100101"},  //+
  {"00000000"},  //
  {"10000001"},  //-
  {"00000000"},  //
  {"00010010"},  ///
  {"00100100"},  //0
  {"00010000"},  //1
  {"10000100"},  //2
  {"10000000"},  //3
  {"10100000"},  //4
  {"10100000"},  //5
  {"10100100"},  //6
  {"00000000"},  //7
  {"10100100"},  //8
  {"10100000"},  //9
  {"00000000"},  //
  {"00000000"},  //
  {"00000000"},  //
  {"00000000"},  //
  {"00000000"},  //
  {"00000000"},  //
  {"10100000"},  //@
  {"10000001"},  //A
  {"10100100"},  //B
  {"00000000"},  //C
  {"00100100"},  //D
  {"00000001"},  //E
  {"00000001"},  //F
  {"10000000"},  //G
  {"10000001"},  //H
  {"00100100"},  //I
  {"00000000"},  //J
  {"00011001"},  //K
  {"00000000"},  //L
  {"01010000"},  //M
  {"01001000"},  //N
  {"00000000"},  //O
  {"10000001"},  //P
  {"00001000"},  //Q
  {"10001001"},  //R
  {"10000001"},  //S
  {"00100100"},  //T
  {"00000000"},  //U
  {"00010010"},  //V
  {"00001010"},  //W
  {"01011010"},  //X
  {"10000001"},  //Y
  {"00010010"},  //Z
  {"00100100"},  //[
  {"01001000"},  //\
  {"00100100"},  //]
  {"00001010"},  //^
  {"00000000"},  //_
  {"01000000"},  //`
  {"00000101"},  //a
  {"00000101"},  //b
  {"00000001"},  //c
  {"00100101"},  //d
  {"00000011"},  //e
  {"10100101"},  //f
  {"00100101"},  //g
  {"00000101"},  //h
  {"00000100"},  //i
  {"00100100"},  //j
  {"00111100"},  //k
  {"00100100"},  //l
  {"10000101"},  //m
  {"00000101"},  //n
  {"00000101"},  //o
  {"00100001"},  //p
  {"00100101"},  //q
  {"00000001"},  //r
  {"00000101"},  //s
  {"00000001"},  //t
  {"00000100"},  //u
  {"00000010"},  //v
  {"00001010"},  //w
  {"01011010"},  //x
  {"00100101"},  //y
  {"00000011"},  //z
  {"00100101"},  //{
  {"00100100"},  //|
  {"10100100"},  //}
  {"10010011"},  //~
  {"00000000"},  //
};

#define Interval_Message 1200
#define MAX7219_DATA 2
#define MAX7219_CLOCK 4
#define MAX7219_LOAD 3
#define LdInner 9
#define LdOuter 8

unsigned long time1 = 0; // timer function
int x = 0; // message counter

// Various 16 character strings to display
const char string_0[] PROGMEM = " PERSISTANCE OF ";
const char string_1[] PROGMEM = "   VISION DEMO  ";
const char string_2[] PROGMEM = "USES Arduino Uno";
const char string_3[] PROGMEM = " Some AND gates ";
const char string_4[] PROGMEM = "MAX7219 and 16- ";
const char string_5[] PROGMEM = "Segment displays";
const char string_6[] PROGMEM = "                ";

// Load the above strings into progmem
const char *const string_table[] PROGMEM = {string_0, string_1, string_2, string_3, string_4, string_5, string_6};
// 16 characters + 1 null
char buffer[17];

void initialize() {
  pinMode(MAX7219_LOAD, OUTPUT);
  pinMode(MAX7219_CLOCK, OUTPUT);
  pinMode(MAX7219_DATA, OUTPUT);
  pinMode(LdInner, OUTPUT);
  pinMode(LdOuter, OUTPUT);
  digitalWrite(MAX7219_LOAD, LOW);
  digitalWrite(LdInner, LOW);
  digitalWrite(LdOuter, LOW);
}
// -------------------------------------------------------------------------------------------------------------------------------------------
// Note: the 'data' is 16 bits which are split into highByte (for U6) and lowByte (for U2)
void OuterSegments(byte address, word data) {
  // AND Gate U1 sections A (clock signal) and D (load signal)
  digitalWrite(LdOuter, HIGH);

  // U2 first gets the high byte (Upper 8 Displays Outer Segments) from the UNO
  shiftOut(MAX7219_DATA, MAX7219_CLOCK, MSBFIRST, address);
  shiftOut(MAX7219_DATA, MAX7219_CLOCK, MSBFIRST, highByte(data));

  // U2 now shifts the high byte into U6 while U2 gets the low byte (Lower 8 Displays Outer Segments)
  shiftOut(MAX7219_DATA, MAX7219_CLOCK, MSBFIRST, address);
  shiftOut(MAX7219_DATA, MAX7219_CLOCK, MSBFIRST, lowByte(data));

  // Load U2 and U6
  digitalWrite(MAX7219_LOAD, HIGH);
  digitalWrite(MAX7219_LOAD, LOW);
  digitalWrite(LdOuter, LOW);
}
// Note: the 'data' is 16 bits which are split into highByte (for U9) and lowByte (for (U5)
void InnerSegments(byte address, word data) {
  digitalWrite(LdInner, HIGH); // AND Gate U1 sections B (clock signal) and C (load signal)

  // U5 first gets the high byte (Upper 8 Displays Inner Segments) from the UNO
  shiftOut(MAX7219_DATA, MAX7219_CLOCK, MSBFIRST, address);
  shiftOut(MAX7219_DATA, MAX7219_CLOCK, MSBFIRST, highByte(data));
  
  // U5 now shifts the high byte into U9 while U5 gets the low byte (Lower 8 Displays Inner Segments)
  shiftOut(MAX7219_DATA, MAX7219_CLOCK, MSBFIRST, address);
  shiftOut(MAX7219_DATA, MAX7219_CLOCK, MSBFIRST, lowByte(data));

  // Load U5 and U9
  digitalWrite(MAX7219_LOAD, HIGH);
  digitalWrite(MAX7219_LOAD, LOW);
  digitalWrite(LdInner, LOW);
}

// these are U2 and U6 Control Register Commands (data is 8 bits)
void CmdO(byte address, byte data) {
  // AND Gate U1 sections A (clock signal) and D (load signal)
  digitalWrite(LdOuter, HIGH);

  // U2 first gets the address and data from the UNO
  shiftOut(MAX7219_DATA, MAX7219_CLOCK, MSBFIRST, address);
  shiftOut(MAX7219_DATA, MAX7219_CLOCK, MSBFIRST, data);

  // U2 shifts into U6 (Note: U2 and U6 get the identical address and data)
  shiftOut(MAX7219_DATA, MAX7219_CLOCK, MSBFIRST, address);
  shiftOut(MAX7219_DATA, MAX7219_CLOCK, MSBFIRST, data);

  // Load U2 and U6
  digitalWrite(MAX7219_LOAD, HIGH);
  digitalWrite(MAX7219_LOAD, LOW);
  digitalWrite(LdOuter, LOW);
}

// these are U5 and U9 Control Register Commands (data is 8 bits)
void CmdI(byte address, byte data) {
  // AND Gate U1 sections B (clock signal) and C (load signal)
  digitalWrite(LdInner, HIGH);

  // U5 first gets the address and data from the UNO
  shiftOut(MAX7219_DATA, MAX7219_CLOCK, MSBFIRST, address);
  shiftOut(MAX7219_DATA, MAX7219_CLOCK, MSBFIRST, data);

  // U5 shifts into U9 (Note: U5 and U9 get the identical address and data)
  shiftOut(MAX7219_DATA, MAX7219_CLOCK, MSBFIRST, address);
  shiftOut(MAX7219_DATA, MAX7219_CLOCK, MSBFIRST, data);

  // Load U5 and U9
  digitalWrite(MAX7219_LOAD, HIGH);
  digitalWrite(MAX7219_LOAD, LOW);
  digitalWrite(LdInner, LOW);
}

// --------------------------------------------------------------------

void setup() {
  // MAX7219 Control Register Set-Up
  initialize();

  // Outer Segment Set-Up (U2 and U6 - See MAX7219 Data Sheet page 7)
  CmdO(0x0C, 0x00); // shutdown register
  CmdO(0x0F, 0x00); // display test register - test mode off
  CmdO(0x0B, 0x07); // scan limit register - display digits 0-7
  CmdO(0x0A, 0x08); // intensity register - set display brightness
  CmdO(0x09, 0x00); // decode mode register - set individual segments
  CmdO(0x00, 0000); // No-Op

  // Inner Segment Set-Up (U5 and U9 - See Max7219 Data Sheet page 7)
  CmdI(0x0c, 0x00); // shutdown register
  CmdI(0x0f, 0x00); // display test register - test mode off
  CmdI(0x0b, 0x07); // scan limit register - display digits 0-7
  CmdI(0x0a, 0x08); // intensity register - set display brightness
  CmdI(0x09, 0x00); // decode mode register - set individual segments
  CmdI(0x00, 0000); // No-Op
}

// -----------------------------------------------------------------------

void get_message(int msg) {
  // get message string from progmem
  strcpy_P(buffer, (char *)pgm_read_word(&(string_table[msg])));
  String tempString = buffer;
  char outSeg [MAX_SIZE];
  char inSeg [MAX_SIZE];

  for (int z = 0; z < 8; z++) {
    int get_asciiHOO = tempString.charAt(z);
    // Get the high order (Displays 9 thru 16) Outer Segment Codes from progmem
    memcpy_P (&outSeg, &OSeg [get_asciiHOO - 32], sizeof outSeg);
    char *Lo1;
    int OuterHigh = strtol(outSeg, &Lo1, 2);

    int get_asciiLOO = tempString.charAt(z + 8);
    // Get the low order (Displays 1 thru 8) Outer Segment Codes from progmem
    memcpy_P (&outSeg, &OSeg [get_asciiLOO - 32], sizeof outSeg);
    char *Lo2;
    int OuterLow = strtol(outSeg, &Lo2, 2);

    // create the 16 bit word where 'high' is display 16, 'low' is display 8;
    // each iteration thru this loop decrements until 'high' 
    // is display 9 and 'low' is display 1
    word OUTERdata = 0;
    OUTERdata = word(OuterHigh, OuterLow);
    OuterSegments(8 - z, OUTERdata);
  }

  for (int z = 0; z < 8; z++) {
    int get_asciiHOI = tempString.charAt(z);
    // Get the high order (Displays 9 thru 16) Inner Segment Codes from progmem
    memcpy_P (&inSeg, &ISeg[get_asciiHOI - 32], sizeof inSeg);
    char *Li1;
    int InnerHigh = strtol(inSeg, &Li1, 2);

    int get_asciiLOI = tempString.charAt(z + 8);
    // Get the low order (Displays 1 thru 8) Inner Segment Codes from progmem
    memcpy_P(&inSeg, &ISeg[get_asciiLOI - 32], sizeof inSeg);
    char *Li2;
    int InnerLow = strtol(inSeg, &Li2, 2);

    // create the 16 bit word where 'high' is display 16, 'low' is display 8;
    // each iteration thru this loop decrements until 'high'
    // is display 9 and 'low' is display 1
    word INNERdata = 0;
    INNERdata = word(InnerHigh, InnerLow);
    InnerSegments(8 - z, INNERdata);
  }
}

void loop() {
  // alternate inner segment chips (U5 and U9) and outer segment chips (U2 and U6) shutdown modes
  // the human eye cannot perceive the switch between inner and outer segments
  CmdO(0x0c, 0001); // U2 and U6 exit Shutdown Mode
  delay(10);
  CmdO(0x0c, 0000); // U2 and U6 enter Shutdown Mode
  CmdI(0x0c, 0001); // U5 and U9 exit Shutdown Mode
  delay(10);
  CmdI(0x0c, 0000); // U5 and U9 enter Shutdown Mode

  if (millis() > time1 + Interval_Message) {
    time1 = millis();
    get_message(x);
    x++;
    if (x == 7) x = 0;
  }
}