How to make SMS sender using eye blinking
- Kanti Sharma
- Dec 20, 2023
- 3 min read
Circuit:
Morse Code:
Programming:
#include <LiquidCrystal.h>
const char CLEAR = 0;
const char DOT = 1;
const char DASH = 2;
const char alphabet[26][6] {
{ 'A', DOT, DASH, CLEAR, CLEAR, CLEAR},
{ 'B', DASH, DOT, DOT, DOT, CLEAR},
{ 'C', DASH, DOT, DASH, DOT, CLEAR},
{ 'D', DASH, DOT, DOT, CLEAR, CLEAR},
{ 'E', DOT, CLEAR, CLEAR, CLEAR, CLEAR},
{ 'F', DOT, DOT, DASH, DOT, CLEAR},
{ 'G', DASH, DASH, DOT, CLEAR, CLEAR},
{ 'H', DOT, DOT, DOT, DOT, CLEAR},
{ 'I', DOT, DOT, CLEAR, CLEAR, CLEAR},
{ 'J', DOT, DASH, DASH, DASH, CLEAR},
{ 'K', DASH, DOT, DASH, CLEAR, CLEAR},
{ 'L', DOT, DASH, DOT, DOT, CLEAR},
{ 'M', DASH, DASH, CLEAR, CLEAR, CLEAR},
{ 'N', DASH, DOT, CLEAR, CLEAR, CLEAR},
{ 'O', DASH, DASH, DASH, CLEAR, CLEAR},
{ 'P', DOT, DASH, DASH, DOT, CLEAR},
{ 'Q', DASH, DASH, DOT, DASH, CLEAR},
{ 'R', DOT, DASH, DOT, CLEAR, CLEAR},
{ 'S', DOT, DOT, DOT, CLEAR, CLEAR},
{ 'T', DASH, CLEAR, CLEAR, CLEAR, CLEAR},
{ 'U', DOT, DOT, DASH, CLEAR, CLEAR},
{ 'V', DOT, DOT, DOT, DASH, CLEAR},
{ 'W', DOT, DASH, DASH, CLEAR, CLEAR},
{ 'X', DASH, DOT, DOT, DASH, CLEAR},
{ 'Y', DASH, DOT, DASH, DASH, CLEAR},
{ 'Z', DASH, DASH, DOT, DOT, CLEAR}
};
const unsigned long dotDuration = 1000; // duration [ms] of a dot; basic time unit
const unsigned long tolerance = 500; // duration that dash, dot or gap may deviate from the ideal length in order to still be recognized
const unsigned long dashDuration = 3 * dotDuration;
const unsigned long shortGap = dotDuration;
const unsigned long mediumGap = 3 * dotDuration;
const unsigned long longGap = 7 * dotDuration;
// current state of the button
enum State {
UP = 0,
DOWN = 1 } state;
// time index of the last button state change (from up to down or down to up)
unsigned long lastChange;
// duration of the last button press
unsigned long downDuration;
// dash-dot-sequence of the current character
char character[5];
// index of the next dot/dash in the current character
int characterIndex;
// the next thing to do
enum Action {
START = 0,
READ_DASHDOT = 1,
READ_CHARACTER = 2,
READ_WORD = 3
} action;
// pin to which the button is connected
int buttonPin = 6;
// pin to which the buzzer is connected
int buzzerPin = 9;
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
void setup() {
Serial.begin(9600);
lcd.begin(16, 2);
pinMode(buttonPin, INPUT_PULLUP);
state = UP;
characterIndex = 0;
downDuration = 0;
lastChange = 0;
action = START;
}
// reset the dash-dot-sequence of the current character
void clearCharacter() {
characterIndex = 0;
for (int i = 0; i < 5; ++i) {
character[i] = CLEAR;
}
}
// determine the next dash or dot in the dash-dot sequence of the current character
void readDashDot() {
Serial.print("Down duration was: ");
Serial.println(downDuration);
if (downDuration >= dashDuration - tolerance && downDuration < dashDuration + tolerance) {
character[characterIndex] = DASH;
Serial.println("DASH");
characterIndex++;
} else if (downDuration >= dotDuration - tolerance && downDuration < dotDuration + tolerance) {
character[characterIndex] = DOT;
Serial.println("DOT");
characterIndex++;
} else {
Serial.println("Down duration unrecognized");
}
}
// interpret the current dash-dot-sequence as a character
char readCharacter() {
bool found;
for (int i = 0; i < 26; ++i) {
found = true;
for (int j = 0; found && j < 5; ++j) {
if (character[j] != alphabet[i][j + 1]) {
found = false;
}
}
if (found) {
return alphabet[i][0];
}
}
return 0;
}
void loop() {
State newState = digitalRead(buttonPin) ? UP : DOWN;
// if the button is pressed, play a tone
if (newState == DOWN) {
tone(buzzerPin, 800);
} else {
noTone(buzzerPin);
}
if (newState == state) {
if (newState == UP) {
// calculate the the time the button has been in UP state
unsigned long upDuration = (millis() - lastChange);
if (action == READ_DASHDOT && upDuration >= shortGap - tolerance && upDuration < shortGap + tolerance) {
readDashDot();
action = READ_CHARACTER;
} else if (action == READ_CHARACTER && upDuration >= mediumGap - tolerance && upDuration < mediumGap + tolerance) {
char c = readCharacter();
if (c != 0) {
// a valid character has been recognized
Serial.print("Read character: ");
Serial.println(c);
lcd.print(c);
} else {
Serial.println("Unrecognized character");
}
clearCharacter();
action = READ_WORD;
} else if (action == READ_WORD && upDuration >= longGap - tolerance && upDuration < longGap + tolerance) {
Serial.println("Read next word");
lcd.print(' ');
action = READ_DASHDOT;
}
} else {
downDuration = (millis() - lastChange);
}
} else {
if (state == UP && newState == DOWN) {
downDuration = 0;
}
lastChange = millis();
state = newState;
action = READ_DASHDOT;
}
}
Demo Video:
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