arduino: 模拟按键(key)

代码：(key.rar)

//ADKeyboard Module
//Developed by DFRobot.com
//Last modified 30/11/2011
//Version 1.0
int adc_key_val[5] = {50, 200, 400, 600, 800 };
int NUM_KEYS = 5;
int adc_key_in;
int key = -1;
int oldkey = -1;


// Convert ADC value to key number
int get_key(unsigned int input)
{
    int k;
    for (k = 0; k < NUM_KEYS; k++)
    {
        if (input < adc_key_val[k])
            return k;
    }
    if (k >= NUM_KEYS)k = -1; // No valid key pressed
    return k;
}

void setup()
{
    pinMode(13, OUTPUT); //we'll use the debug LED to output a heartbeat
    Serial.begin(9600); // 9600 bps
}

void loop()
{
    adc_key_in = analogRead(0); // read the value from the sensor
    digitalWrite(13, LOW);
    key = get_key(adc_key_in); // convert into key press

    if (key != oldkey) // if keypress is detected
    {
        delay(50); // wait for debounce time
        adc_key_in = analogRead(0); // read the value from the sensor
        key = get_key(adc_key_in); // convert into key press
        if (key != oldkey)
        {
            oldkey = key;
            if (key >= 0)
            {
                digitalWrite(13, HIGH);
                switch(key)
                {
                case 0:Serial.println("S1 OK");
                    break;
                case 1:Serial.println("S2 OK");
                    break;
                case 2:Serial.println("S3 OK");
                    break;
                case 3:Serial.println("S4 OK");
                    break;
                case 4:Serial.println("S5 OK");
                    break;
                }
            }
        }
    }
    delay(100);
}