ultrasound.ino

#define APP_VERSION 1.1

double distance = 0;
double echo = 0;
int ultraSoundSignal = D0; // Ultrasound signal pin

// Elapsed Millis Stuff
unsigned int publishInterval = 2000;    // Every 2000 ms (2 seconds)
elapsedMillis timeElapsed; //declare global if you don't want it reset every time loop runs


void setup() {
    pinMode(ultraSoundSignal,OUTPUT);
    Spark.publish("status", "{ status: \"started up! "+String(APP_VERSION)+"\"}", 60, PRIVATE );
    Spark.variable("distance", &distance, DOUBLE);
    
    timeElapsed = 0;
}

void loop() {
    if (timeElapsed > publishInterval) 
    {				
        updateDistance();
        timeElapsed = 0;
    }
}

void updateDistance() {
    Spark.publish("status", "{ status: updateDistance}", 60, PRIVATE );
    pinMode(ultraSoundSignal, OUTPUT); // Switch signalpin to output
    digitalWrite(ultraSoundSignal, LOW); // Send low pulse
    delayMicroseconds(2); // Wait for 2 microseconds
    digitalWrite(ultraSoundSignal, HIGH); // Send high pulse
    delayMicroseconds(5); // Wait for 5 microseconds
    digitalWrite(ultraSoundSignal, LOW); // Holdoff
    pinMode(ultraSoundSignal, INPUT); // Switch signalpin to input
    digitalWrite(ultraSoundSignal, HIGH); // Turn on pullup resistor
    // please note that pulseIn has a 1sec timeout, which may
    // not be desirable. Depending on your sensor specs, you
    // can likely bound the time like this -- marcmerlin
    // echo = pulseIn(ultraSoundSignal, HIGH, 38000)
    echo = pulseIn(ultraSoundSignal, HIGH); //Listen for echo
    distance = (echo / 58.138);// * .39; //convert to CM then to inches
    // distance = round(distance);
    Spark.publish("distance", "Outside: " + String(distance));
    if (distance <= 100) {
        Spark.publish("distance", String(distance));    //it just posts one time? why?
    }
}

double pulseIn(uint16_t pin, uint8_t state) {
    
    GPIO_TypeDef* portMask = (PIN_MAP[pin].gpio_peripheral); // Cache the target's peripheral mask to speed up the loops.
    uint16_t pinMask = (PIN_MAP[pin].gpio_pin); // Cache the target's GPIO pin mask to speed up the loops.
    unsigned long pulseCount = 0; // Initialize the pulseCount variable now to save time.
    unsigned long loopCount = 0; // Initialize the loopCount variable now to save time.
    unsigned long loopMax = 20000000; // Roughly just under 10 seconds timeout to maintain the Spark Cloud connection.
    
    // Wait for the pin to enter target state while keeping track of the timeout.
    while (GPIO_ReadInputDataBit(portMask, pinMask) != state) {
        if (loopCount++ == loopMax) {
            return 0;
        }
    }
    
    // Iterate the pulseCount variable each time through the loop to measure the pulse length; we also still keep track of the timeout.
    while (GPIO_ReadInputDataBit(portMask, pinMask) == state) {
        if (loopCount++ == loopMax) {
            return 0;
        }
        pulseCount++;
    }
    
    // Return the pulse time in microseconds by multiplying the pulseCount variable with the time it takes to run once through the loop.
    return pulseCount * 0.405; // Calculated the pulseCount++ loop to be about 0.405uS in length.
}