Published January 11, 2022 © MIT

Casio Calculator External Memory (Casio FX92+)

An external, detachable memory module allowing you to save those long programs that become a heavy task to rewrite.

IntermediateShowcase (no instructions)2,672

Casio Calculator External Memory (Casio FX92+)

Things used in this project

Hardware components

Arduino Nano R3

CD4066 Quad Bilateral Switch

Tactile Switch, Top Actuated

Resistor 10k ohm

Hand tools and fabrication machines

Soldering iron (generic)

Solder Wire, Lead Free

Story

The inspiration for this project came initially from the Casio 92B, which was the recommended calculator for the humanities in Belgium and France. Unfortunately the 92B, except for its elegance, was not very impressive...

Having recently discovered the 92+ and its algorithmic mode just after high school, I was happy to see that "the" calculator that had been with me for six years was going to keep me busy for a while!

...The only disappointment was of course that the 92+ has no internal memory.

So I thought it would be interesting to create an external, detachable memory module to be able to save those long programs that become a heavy task to rewrite.

Although this module can be compatible with any calculator (or any device with a matrix keyboard), it was primarily designed for the Casio FX-92+.

The Module

An Arduino microcontroller at the heart of the module drives the four integrated circuits (CD4066), which in turn simulate a key press on the calculator. A CD4066 IC consists of 4 bilateral electronic switches, a key on the calculator is "pressed" when the electronic switch corresponding to the column and the electronic switch corresponding to the row of the desired key are activated simultaneously.

At the bottom of the module, 5 buttons are used to select one of the 5 algorithms stored in the EEPROM of the arduino. Each algorithm can contain 200 instructions/keystroke coordinates.

MATRIXIO

MATRIXIO is a program to load the algorithms into the arduino's EEPROM. The Instructions and key coordinates can be sent manually via the arduino IDE serial monitor, or automatically via a loader written in Python. (available here: github.com/adityachugh02/casio-external-memory)

After uploading MATRIXIO to the arduino, set the serial monitor line ending to "newline".

MATRIXIO v1.0 (c) Jan 2022 Aditya Chugh -type 'help'-

Commands:
xy : 		Instruction, where x is column and y is row of calculator key
a~t : 		Shortcut instruction sequences
write : 	Enable writing of instructions to EEPROM memory
read : 		Disable enable writing of instructions to EEPROM memory
prog 1~5 : 	Memory address set to beginning of program 1~5
clear 1~5 : 	Clears all 200 instructions of program 1~5
list 1~5 : 	Lists all 200 instructions of program 1~5
addr 0~999 : 	Memory address set to 0~999 (for uno & nano)
On Casio FX-92B & FX-92+, the bottom-most row is matrixed differently, keys should hence be addressed as such : 
'0' : 65
',' : 64
'x10^x' : 63
'ANS/REP' : 62
'EXE' : 61
Shortcut instruction sequences for Casio FX-92+:
a : avancer de
b : tourner de
c : s'orienter à
d : aller à x,y
e : stylo écrit
f : stylo relevé
g : mettre var à
h : demander valeur
i : commentaire
j : afficher résultat
k : style
l : attendre
m : répéter
n : répéter jusqu'à
o : si alors
p : si alors sinon
q : exécuter
r : copier et insérer
s : insérer ligne
t : tout supprimer

Keyboard Matrix

1 / 2

Code

#include <EEPROM.h>

int col_map[] = {11, 12, 13, 14, 15, 16, 2 }; //column pins
int row_map[] = {2, 3, 4, 5, 6, 7, 8, 9, 10 }; //row pins
int addr = 0; //eeprom address
int write_mode = 0;
int instruction_delay = 80;

//sequences:

int sequences[][10] = {{07,01},//avancer de
{07,11},//tourner de
{07,21},//s'orienter 
{07,02},//aller  x,y

{07,37,01},//stylo crit
{07,37,11},//stylo relev
{07,37,21},//mettre var 
{07,37,02},//demander valeur

{07,37,00,37,00,01},//commentaire
{07,37,00,37,00,11},//afficher rsultat
{07,37,00,37,00,21},//style
{07,37,00,37,00,02},//attendre

{07,37,00,37,00,37,00,01},//rpter
{07,37,00,37,00,37,00,11},//rpter jusqu'
{07,37,00,37,00,37,00,21},//si alors
{07,37,00,37,00,37,00,02},//si alors sinon

{07,37,00,37,00,37,00,37,00,01},//excuter
{07,37,00,37,00,37,00,37,00,11},//copier et insrer
{07,37,00,37,00,37,00,37,00,21},//insrer ligne
{07,37,00,37,00,37,00,37,00,02}};//tout supprimer

void setup() {
  Serial.begin(9600);
  DDRD = B11111110;
  DDRB = B111111;
  DDRC = B00000111;

  //pinMode(A7, INPUT_PULLUP); //add pull-up ressistor
  //pinMode(A6, INPUT_PULLUP); //add pull-up ressistor
  pinMode(A5, INPUT_PULLUP);
  pinMode(A4, INPUT_PULLUP);
  pinMode(A3, INPUT_PULLUP);
  Serial.println("MATRIXIO v1.0 (c) Jan 2022 Aditya Chugh -type 'help'-");
  Serial.println("");
}

void loop() {
  if (Serial.available() > 0) {
    String availableString = Serial.readString();
    availableString.replace(" ", "");
    
    //if (availableString.length() > 3){
      
      if (availableString.indexOf("lear") > 0){
        Serial.print("Clearing prog ");
        Serial.print(availableString[5]);
        Serial.print("...");
        int i = (String(availableString[5]).toInt()-1)*200;
        int f = i + 200;
        for (i; i < f ; i++) {
          EEPROM.write(i, 0);
        }
        Serial.println("Done.");
      } 

      if (availableString.indexOf("ist") > 0){
        int i = (String(availableString[4]).toInt()-1)*200;
        int f = i + 200;
        for (i; i < f ; i++) {
          Serial.print("Address, Instruction: ");
          Serial.print(i);
          Serial.print(", ");
          if (EEPROM.read(i) > 96){
            Serial.print(char(EEPROM.read(i)));
          } else {
            Serial.print(EEPROM.read(i));
          }
          Serial.println("");
        }
        
      }

      if (availableString.indexOf("rog") > 0){
        addr = (String(availableString[4]).toInt() - 1)*200;
        Serial.print("prog " + String(availableString[4]));
        Serial.print(" address: ");
        Serial.println(addr);
      }
      
      if (availableString.indexOf("ddr") > 0){
        String subString = availableString;
        subString.remove(0,4);
        addr = subString.toInt();
        Serial.print("Address set to: ");
        Serial.println(addr);
      }

      if (availableString.indexOf("rite") > 0){
        write_mode = 1;
        Serial.println("Write mode enabled");
      }

      if (availableString.indexOf("ead") > 0){
        write_mode = 0;
        Serial.println("Write mode disabled");
      }

      if (availableString.indexOf("elp") > 0){
        write_mode = 0;
        Serial.println(F("Commands:\n\nxy :         Instruction, where x is column and y is row of calculator key\na~t :        Shortcut instruction sequences\nwrite :      Enable writing of instructions to EEPROM memory\nread :       Disable enable writing of instructions to EEPROM memory\nprog 1~5 :   Memory address set to beginning of program 1~5\nclear 1~5 :  Clears all instructions of program 1~5\nlist 1~5 :   Lists all instructions of program 1~5\naddr 0~999 : Memory address set to 0~999 (for uno & nano)\n"));
        Serial.println(F("On Casio FX-92B & FX-92+, the bottom-most row is matrixed differently, keys should be addressed as such:\n\n'0' : 65\n',' : 64\n'x10^x' : 63\n'ANS/REP' : 62\n'EXE' : 61\n"));
        Serial.println(F("Shortcut instruction sequences for Casio FX-92+:\n\na : avancer de\nb : tourner de\nc : s'orienter \nd : aller  x,y\n\ne : stylo crit\nf : stylo relev\ng : mettre var \nh : demander valeur\n\ni : commentaire\nj : afficher rsultat\nk : style\nl : attendre\n\nm : rpter\nn : rpter jusqu'\no : si alors\np : si alors sinon\n\nq : excuter\nr : copier et insrer\ns : insrer ligne\nt : tout supprimer\n"));
      }
      
    //}
  
    if (availableString.length() == 3){
      str_to_button_press(availableString);
      if (write_mode == 1){
        str_to_int_to_eeprom(availableString);
      }
    }

    if (availableString.length() == 2){
      sequence_to_button_press(availableString);
      if (write_mode == 1){
        int i = availableString[0];
        str_to_int_to_eeprom(String(i));
      }
    }
  }
  /*if (analogRead(A7) == 0) {
    Serial.println("Program 5");
    eeprom_read(800);
  }
  if (digitalRead(A6) == LOW) {
    Serial.println("Program 4");
    eeprom_read(600);
  }*/
  if (digitalRead(A5) == LOW) {
    Serial.println("Program 3");
    eeprom_read(400);
  }
  if (digitalRead(A4) == LOW) {
    Serial.println("Program 2");
    eeprom_read(200);
  }
  if (digitalRead(A3) == LOW) {
    Serial.println("Program 1");
    eeprom_read(0);
  }
}

void str_to_button_press(String availableString){
  
  int col = String(availableString[0]).toInt();
  int row = String(availableString[1]).toInt();
  Serial.print ("Address, Instruction: ");
  Serial.print(addr);
  Serial.print("," ),
  Serial.print(col);
  Serial.print(row);
  Serial.println("");
  digitalWrite(col_map[col], HIGH);
  digitalWrite(row_map[row], HIGH);
  delay(instruction_delay);
  digitalWrite(col_map[col], LOW);
  digitalWrite(row_map[row], LOW);
  delay(20);
  if (availableString == "61"){
    delay(500);
  }
}

void str_to_int_to_eeprom (String availableString){
  EEPROM.write(addr, availableString.toInt());
  addr = addr + 1;
}

void sequence_to_button_press (String availableString){
  int sequence = int(availableString[0])-97;
  Serial.print("Address, Instruction: ");
  Serial.print(addr);
  Serial.print("," ),
  Serial.println(availableString[0]);
  for (int i = 0 ; i < 10 ; i++){
    str_to_button_press(int_to_str(sequences[sequence][i]));
  }
}

String int_to_str (int Int){
  if (Int > 10){
    return String(Int);
  } else {
    if (0 < Int < 10){
      String subString = "0";
      subString += String(Int);
      return(subString);
    }
  }
}

void eeprom_read(int Start){
  int Stop = Start + 200;
  for (addr = Start; addr < Stop ; addr++) {
    if (EEPROM.read(addr) > 96){
      sequence_to_button_press(String(char(EEPROM.read(addr))));
    } else {
      str_to_button_press(int_to_str(EEPROM.read(addr)));
    }
  }
  addr = 0;
}

import serial
import time

port = input("COM Port: ")
arduino = serial.Serial(port=port, baudrate=9600, timeout=1)

filename = input("Filename: ")

lines = []
f = open(filename)
lines = f.readlines()


print(arduino.readlines())
time.sleep(1)
arduino.write(bytes(str("write"), 'utf-8'))
time.sleep(1)
print(arduino.readlines())
arduino.write(bytes(str(str("prog")+input("enter program number 1~5: ")), 'utf-8'))
time.sleep(1)
print(arduino.readlines())

for line in lines:
    time.sleep(2)
    receive = arduino.readlines()
    print(receive)
    print(line)
    arduino.write(bytes(str(line), 'utf-8'))

Credits

adityachugh

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Casio Calculator External Memory (Casio FX92+)

Things used in this project

Hardware components

Hand tools and fabrication machines

Story

The Module

MATRIXIO

Keyboard Matrix

Schematics

Schematic

CD4066

Code

MATRIXIO

Python Algorithm Uploader

Credits

adityachugh

Comments

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Casio Calculator External Memory (Casio FX92+)

Casio Calculator External Memory (Casio FX92+)

Things used in this project

Hardware components

Hand tools and fabrication machines

Story

The Module

MATRIXIO

Keyboard Matrix

Schematics

Schematic

CD4066

Code

MATRIXIO

Python Algorithm Uploader

Credits

adityachugh

Comments

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