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@smittytone
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Arduino Leonardo code for ZX81 USB Keyboard
// ZX81 USB Keyboard for Leonardo
// (c) Dave Curran
// 2013-04-27
// Modified with Function keys by Tony Smith
// 2014-02-15
#define NUM_ROWS 8
#define NUM_COLS 5
#define SHIFT_COL 4
#define SHIFT_ROW 5
#define DEBOUNCE_VALUE 250
#define REPEAT_DELAY 500
#define ALT_KEY_ON 255
#define ALT_KEY_OFF 0
// Keymap for normal use
byte keyMap[NUM_ROWS][NUM_COLS] =
{
{'5', '4', '3', '2', '1'},
{'t', 'r', 'e', 'w', 'q'},
{'6', '7', '8', '9', '0'},
{'g', 'f', 'd', 's', 'a'},
{'y', 'u', 'i', 'o', 'p'},
{'v', 'c', 'x', 'z', 0},
{'h', 'j', 'k', 'l', KEY_RETURN},
{'b', 'n', 'm', '.', ' '}
};
// Keymap if Shift is pressed
byte keyMapShifted[NUM_ROWS][NUM_COLS] =
{
{KEY_LEFT_ARROW, '$', '\\', '@', KEY_ESC},
{'T', 'R', 'E', 'W', 'Q'},
{KEY_DOWN_ARROW, KEY_UP_ARROW, KEY_RIGHT_ARROW, '!', KEY_BACKSPACE},
{'G', 'F', 'D', 'S', 'A'},
{'Y', 'U', 'I', 'O', 'P'},
{'V', 'C', 'X', 'Z', 0},
{'H', 'J', 'K', 'L', KEY_F5},
{'B', 'N', 'M', ',', '#'}
};
// Keymap if Function-Shift pressed
// NEXT key read should be from this table
byte keyMapAlt[NUM_ROWS][NUM_COLS] =
{
{KEY_LEFT_ARROW, '}}', '{{', ']', '['},
{'=', '$', '(', ')', '""'},
{KEY_DOWN_ARROW, KEY_UP_ARROW, KEY_RIGHT_ARROW, '!', KEY_BACKSPACE},
{0, '_', '~', '|', '@'},
{'>', '$', '(', ')', '""'},
{'/', '?', ';', ':', 0},
{'*', '-', '+', '=', KEY_RETURN},
{'*', '<', '>', '\'', '#'}
};
// Global Variables
int debounceCount[NUM_ROWS][NUM_COLS];
int altKeyFlag;
// Define the row and column pins
byte colPins[NUM_COLS] = {13, 12, 11, 10, 9};
byte rowPins[NUM_ROWS] = {7, 6, 5, 4, 3, 2, 1, 0};
// SETUP
void setup()
{
// Set all pins as inputs and activate pull-ups
for (byte c = 0 ; c < NUM_COLS ; c++)
{
pinMode(colPins[c], INPUT);
digitalWrite(colPins[c], HIGH);
// Clear debounce counts
for (byte r = 0 ; r < NUM_ROWS ; r++)
{
debounceCount[r][c] = 0;
}
}
// Set all pins as inputs
for (byte r = 0 ; r < NUM_ROWS ; r++)
{
pinMode(rowPins[r], INPUT);
}
// Function key is NOT pressed
altKeyFlag = ALT_KEY_OFF;
// Initialise the keyboard
Keyboard.begin();
}
// LOOP
void loop()
{
bool shifted = false;
bool keyPressed = false;
// Check for the Shift key being pressed
pinMode(rowPins[SHIFT_ROW], OUTPUT);
if (digitalRead(colPins[SHIFT_COL]) == LOW) shifted = true;
if (shifted == true && altKeyFlag == ALT_KEY_ON)
{
// NOP to prevent Function selection from autorepeating
}
else
{
pinMode(rowPins[SHIFT_ROW], INPUT);
for (byte r = 0 ; r < NUM_ROWS ; r++)
{
// Run through the rows, turn them on
pinMode(rowPins[r], OUTPUT);
digitalWrite(rowPins[r], LOW);
for (byte c = 0 ; c < NUM_COLS ; c++)
{
if (digitalRead(colPins[c]) == LOW)
{
// Increase the debounce count
debounceCount[r][c]++;
// Has the switch been pressed continually for long enough?
int count = debounceCount[r][c];
if (count == DEBOUNCE_VALUE)
{
// First press
keyPressed = true;
pressKey(r, c, shifted);
}
else if (count > DEBOUNCE_VALUE)
{
// Check for repeats
count -= DEBOUNCE_VALUE;
if (count % REPEAT_DELAY == 0)
{
// Send repeat
keyPressed = true;
pressKey(r, c, shifted);
}
}
}
else
{
// Not pressed; reset debounce count
debounceCount[r][c] = 0;
}
}
// Turn the row back off
pinMode(rowPins[r], INPUT);
}
digitalWrite(rowPins[SHIFT_ROW], LOW);
}
}
void pressKey(byte r, byte c, bool shifted)
{
// Send the keypress
byte key = shifted ? keyMapShifted[r][c] : keyMap[r][c];
if (key == KEY_F5)
{
// If the Function key pressed (Shift + New Line)
altKeyFlag = ALT_KEY_ON;
key = 0;
debounceCount[r][c] = 0;
}
if (altKeyFlag == ALT_KEY_ON)
{
// Get the Alt key pressed after Function has been selected
key = keyMapAlt[r][c];
altKeyFlag = ALT_KEY_OFF;
}
// send the key
if (key > 0) Keyboard.write(key);
}
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