Cost performance ratio is excellent. All 3 sensors arrived in good condition. But be aware: The HC-SR04 has a well-known bug (or is this really a feature???):
The sensor can stuck after measuring our of range. It delivers zero distance values permanently, even if something is quite close. There is a software workaround:
if (distance==0) {
pinMode(echoPin, OUTPUT);
digitalWrite(echoPin, LOW);
pinMode(echoPin, INPUT);
}

// OR this one

if (distance == 0 && digitalRead(ECHO_PIN) == HIGH) {
pinMode(ECHO_PIN, OUTPUT);
digitalWrite(ECHO_PIN, LOW);
delay(100);
pinMode(ECHO_PIN, INPUT);
}
}

For more see here:
https://forum.arduino.cc/index.php?topic=55119.45
https://bitbucket.org/teckel12/arduino-new-ping/issues/3/hc-sr04-sensor-get-stuck-at-zero

Cost performance ratio is excellent. All 3 sensors arrived in good condition. But be aware: The HC-SR04 has a well-known bug (or is this really a feature???):
The sensor can stuck after measuring our of range. It delivers zero distance values permanently, even if something is quite close. There is a software workaround:
if (distance==0) {
pinMode(echoPin, OUTPUT);
digitalWrite(echoPin, LOW);
pinMode(echoPin, INPUT);
}

// OR this one

if (distance == 0 && digitalRead(ECHO_PIN) == HIGH) {
pinMode(ECHO_PIN, OUTPUT);
digitalWrite(ECHO_PIN, LOW);
delay(100);
pinMode(ECHO_PIN, INPUT);
}
}

For more see here:
https://forum.arduino.cc/index.php?topic=55119.45
https://bitbucket.org/teckel12/arduino-new-ping/issues/3/hc-sr04-sensor-get-stuck-at-zero

Cost performance ratio is excellent. All 3 sensors arrived in good condition. But be aware: The HC-SR04 has a well-known bug (or is this really a feature???):
The sensor can stuck after measuring our of range. It delivers zero distance values permanently, even if something is quite close. There is a software workaround:
if (distance==0) {
pinMode(echoPin, OUTPUT);
digitalWrite(echoPin, LOW);
pinMode(echoPin, INPUT);
}

// OR this one

if (distance == 0 && digitalRead(ECHO_PIN) == HIGH) {
pinMode(ECHO_PIN, OUTPUT);
digitalWrite(ECHO_PIN, LOW);
delay(100);
pinMode(ECHO_PIN, INPUT);
}
}

For more see here:
https://forum.arduino.cc/index.php?topic=55119.45
https://bitbucket.org/teckel12/arduino-new-ping/issues/3/hc-sr04-sensor-get-stuck-at-zero

Produto de qualidade excelente.

Excellent quality product.

Excellent quality product.