Is the problem in the code or in the OLED screen?

Projects Programming
29

Here's an attempt to tidy up your code and make it only react when things change... It takes up quite a bit less memory. The OLED library takes quite a bit so you could be running out with all those large arrays...

#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

// On an arduino UNO:       A4(SDA), A5(SCL)
#define OLED_RESET 4         // Reset pin # (or -1 if sharing Arduino reset pin)
#define SCREEN_ADDRESS 0x3C  ///< See datasheet for Address; 0x3D for 128x64, 0x3C for 128x32
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

const int maxInput = 100;

char InputArray[maxInput]; // stores the selected value from char Input
char Output[maxInput]; // stores the final result to show on screen
char Input[36] = { 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' }; // shows value on screen and allows selection to store in char InputArray
char AlphaNumChart[6][6] = { { 'a', 'b', 'c', 'd', 'e', 'f' },
  { 'g', 'h', 'i', 'j', 'k', 'l' },
  { 'm', 'n', 'o', 'p', 'q', 'r' },
  { 's', 't', 'u', 'v', 'w', 'x' },
  { 'y', 'z', '0', '1', '2', '3' },
  { '4', '5', '6', '7', '8', '9' }
}; // based on coordinates calculated by the formula, will select characters from this matrix to store in char Output

uint8_t num[maxInput];  //indicies of InputArray

const int keyPin = 2; // key to allow selection of the value to store in char InputArray
const int selectionPin = A0;  // rotary pot
int prevKeyState;
int prevSelectionState;
int prevSelectionIdx;

int InputArrayPos = 0; //this is just for word positioning on the display

void setup() {
  pinMode(keyPin, INPUT);
  Serial.begin(9600);
  display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS);
  display.setTextWrap(false);
  display.clearDisplay();
}

void loop() {

  int selectionIdx = map(analogRead(selectionPin), 0, 1023, 0, 36);
  int keyState = digitalRead(keyPin);

  if ( selectionIdx == prevSelectionIdx && keyState == prevKeyState ) {
    // nothing has changed, so nothing to do, exit loop at try again
    return;
  }

  // something has changed, either the character selected or the state of the key

  if ( selectionIdx != prevSelectionIdx ) {
    updateCharSelection(selectionIdx);
    prevSelectionIdx = selectionIdx;
  }

  if ( keyState != prevKeyState ) {
    prevKeyState = keyState;
    if ( selectionIdx < 36 ) {
      // process a key selection
      if (keyState == HIGH) {
        // key was pressed, add it to input
        addCharInput(selectionIdx);
      }
      else {
        // key was released, do nothing
      }
    }
    else {
      // deal with final "Show output" selection
      if (keyState == HIGH) {
        // key was pressed, show output
        calculateOutput();
        displayOutput();
      }
      else {
        // key was released, do nothing
      }
    }
    delay(20);  // debounce key
  }
}

void calculateOutput() {

  for (int i = 0; i < InputArrayPos; i++) {
    int row = num[i] / 6;
    int col = num[InputArrayPos - 1 - i] % 6;
    Output[i] = AlphaNumChart[row][col];
  }
  Output[InputArrayPos] = '\0';
}

void displayOutput() {

  int CursorEnd = (-12 * InputArrayPos) + display.width();
  int CursorStart = 0;
  int CursorRef = 0;
  
  while (digitalRead(keyPin) == HIGH) {

    if (InputArrayPos <= 10) {
      displayPrint(0, 27, WHITE, 2);
      display.println(Output);
      display.display();
    }
    else {
      display.clearDisplay();
      displayPrint(0, 0, WHITE, 1);
      display.println("Your Output:");
      displayPrint(CursorStart, 27, WHITE, 2);
      display.println(Output);
      display.display();
      if (CursorStart == 0) {
        CursorStart = CursorStart - 2;
        CursorRef = 0;
        delay(1000);
      }
      if ((CursorStart < 0) && (CursorRef == 0)) CursorStart = CursorStart - 2;
      if (CursorStart == CursorEnd) {
        CursorStart = CursorStart + 2;
        CursorRef = 1;
        delay(1000);
      }
      if ((CursorStart < 0) && (CursorRef == 1)) CursorStart = CursorStart + 2;
    }
  }
}

void displayPrint(int x, int y, int color, int size) {
  display.setCursor(x, y);
  display.setTextColor(color);
  display.setTextSize(size);
}

void updateCharSelection(int idx) {
  char ch;
  bool onChar;    // true when selection is on a char, false if "Show Output"

  if (idx < 36) {
    ch = Input[idx];
    onChar = true;
  }
  else {
    onChar = false;
  }

  display.clearDisplay();
  if ( onChar ) {
    displayPrint(0, 0, WHITE, 1);
    display.println("Your selection:");
    displayPrint(55, 15, WHITE, 4);
    display.print(ch);
  }
  else {
    displayPrint(0, 22, WHITE, 2);
    display.println("SHOW Output");
  }
  displayInput();
}

void addCharInput(int idx) {

  num[InputArrayPos] = idx; // store index for later computation
  InputArray[InputArrayPos++] = Input[idx];
  InputArray[InputArrayPos] = '\0';
  if ( InputArrayPos >= maxInput - 1 ) {
    InputArrayPos = maxInput - 2;
  }
  display.clearDisplay();
  displayPrint(0, 0, WHITE, 1);
  display.println("Your selection:");
  displayPrint(50, 22, WHITE, 2);
  display.println("OK!");

  displayInput();
}

void displayInput() {
  int cursor = 0;

  if (InputArrayPos > 10) {
    cursor = (10 - InputArrayPos) * 12;
  }
    displayPrint(cursor, 47, WHITE, 2);
    display.println(InputArray);
    display.display();
}