simple rcwl i2c test serial output

RCWL1601_I2C/arduino_simpletest/arduino_simpletest.ino

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+// SPDX-FileCopyrightText: 2022 Limor Fried for Adafruit Industries
+//
+// SPDX-License-Identifier: MIT
+
+#include <Adafruit_I2CDevice.h>
+// requires https://github.com/adafruit/Adafruit_BusIO
+
+#define SR04_I2CADDR 0x57
+Adafruit_I2CDevice sonar_dev = Adafruit_I2CDevice(SR04_I2CADDR);
+
+
+void setup() {
+  Wire.begin();
+  Serial.begin(115200);
+  while (!Serial);
+
+  if (! sonar_dev.begin(&Wire)) {
+    Serial.println("Could not find I2C sonar!");
+    while (1);
+  }
+  Serial.println("Found RCWL I2C sonar!");
+}
+
+void loop() {
+  Serial.print("Ping mm: "); Serial.println(ping_mm());
+  delay(100);
+}
+
+uint32_t ping_mm()
+{
+  uint32_t distance = 0;
+  byte buffer[3];
+  buffer[0] = 1;
+  // write one byte then read 3 bytes
+  if (! sonar_dev.write(buffer, 1)) {
+    return 0;
+  }
+  delay(10);  // wait for the ping echo
+  if (! sonar_dev.read(buffer, 3)) {
+    return 0;
+  }
+  
+  distance = ((uint32_t)buffer[0] << 16) | ((uint32_t)buffer[1] << 8) | buffer[2];
+  distance /= 1000;
+  
+  if ((distance <= 1) || (distance >= 4500)) {   // reject readings too low and too high
+    return 0;
+  }
+
+  return distance;
+}