A GPIO echo meter that sends echo time length over I2C

i2c_meter.ino

#include <Wire.h>

uint32_t ms;
int mode;

#define WIRE_ADDR 0x8

#define TRIGGER 38
#define ECHO 36

void setup() 
{
  // Set up sensor
  pinMode(TRIGGER, OUTPUT);
  pinMode(ECHO, INPUT);
  pinMode(13, OUTPUT);
  mode = 1;
  
  // Start I2C
  Wire.begin(WIRE_ADDR);
  Wire.onRequest(i2cRead);
}

void loop() 
{
  // Make measuremrnt
  digitalWrite(TRIGGER, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIGGER, LOW);
  
  ms = pulseIn(ECHO, HIGH, 1UL << 22);
  digitalWrite(13, mode);
  mode = !mode;
  delay(10);
}

void i2cRead()
{
  Wire.write((const char *)&ms, sizeof(ms));
}