HCSR04

Connects over

GPIO pins

Made by

Cytron / generic

Datasheet

cdn.sparkfun.com

Use it

hardware {
    device hcsr04: HCSR04(trig: 16, echo: 17)
}

every 1s {
    let value: float = hcsr04.distance_cm()
    log("hcsr04", "distance_cm={value}")
}

The HCSR04 is wired to ordinary GPIOs: give each of its pins (trig, echo) as a named argument. The compiler checks every pin can do its job.

Methods

• hcsr04.distance_cm() -> float

  Distance in centimeters

Wiring

Specifications

Voltage

5V (not 3.3V tolerant — use level shifter on ECHO)

Current

15 mA active

Range

2 cm – 4 m (practical: 5 cm – 2 m)

Resolution

~3 mm at close range

Beam angle

≈ 15°

Tips

• ECHO line is 5V — use a 10kΩ/20kΩ divider before feeding into a 3.3V MCU.
• Distance = (echo_us × 0.0343) / 2 cm (speed of sound at 20°C).
• Reflective surfaces and angles below 30° cause missed echoes.

Alternatives worth knowing:

• VL53L0X: Time-of-flight laser, more accurate, much smaller, 3.3V, but max ~2 m and pricier.
• JSN-SR04T: Waterproof variant if you need outdoor / wet use.