M5Stack: UNIT ULTRASONIC-I2C

unit_ultrasonic_i2c.ino

#include <Arduino.h>
#include <Wire.h>

float read_distance() {
  Wire.beginTransmission(0x57);
  Wire.write(0x01);
  Wire.endTransmission();
  ::delay(50);
  if (Wire.requestFrom(0x57, 3) != 3) {
    return -1;
  }
  uint32_t data = Wire.read();
  data = (data << 8) | Wire.read();
  data = (data << 8) | Wire.read();
  return data / 1000.f;
}

void setup() {
  Serial.begin(115200);
  Wire.begin();
}

void loop() {
  auto d = ::read_distance();
  if (d >= 0) {
    Serial.printf("distance: %f mm\r\n", d);
  }
}