ksonic(hcsr04)

C++ implementation

struct State {
};

{{ GENERATED_CODE }}

void evaluate(Context ctx) {

    if (!isInputDirty<input_PING>(ctx))
        return;

    uint8_t echoPort = (uint8_t)getValue<input_ECHO>(ctx);
    uint8_t trigPort = (uint8_t)getValue<input_TRIG>(ctx);
    Number max = getValue<input_MAX>(ctx);

    uint32_t Max_RoundTrip = (uint32_t)(2000000 * max / getValue<input_SOS>(ctx));
    
    // Request measurement: make a pulse for 10 μs.
    pinMode(trigPort, OUTPUT);
    // short pulse for clean high
    digitalWrite(trigPort, LOW);
    delayMicroseconds(5);
    digitalWrite(trigPort, HIGH);
    delayMicroseconds(10);
    digitalWrite(trigPort, LOW);

    // Wait for echo pin rise which means ultrasonic burst success
    uint32_t maxUs = micros() + Max_RoundTrip;
    pinMode(echoPort, INPUT);
    while (digitalRead(echoPort) == LOW) {
        if (micros() > maxUs) {
            emitValue<output_DIST>(ctx, max);
            emitValue<output_DONE>(ctx, 1);
            return;
        }
    }

    // Now wait for echo line to be pulled back low which means echo capture
    uint32_t tStart = micros();

    maxUs = tStart + Max_RoundTrip;
    while (digitalRead(echoPort) == HIGH) {
        if (micros() > maxUs) {
            emitValue<output_DIST>(ctx, -max);
            emitValue<output_DONE>(ctx, 1);
            return;
        }
    }

    Number dist = ((micros() - tStart) * sos * 0.5);
    dist = (dist > max) ? max : (dist < 0) ? 0 : dist ;

    emitValue<output_DIST>(ctx, max);
    emitValue<output_DONE>(ctx, 1);

}

Tabular tests