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Arduino Uno and HY-SRF05 ultrasonic sensor example

The HY-SRF05 is an ultrasonic emitter/receiver used to measure distance with a precision of ~0.3cm. It sends out a 40 KHz square wave signal that reflects on objects in front of the sensor. This signal is then read back by the sensor and the duration of the received signal is reflected on the ECHO pin.


Supply voltage: 4.5V to 5.5V
Supply current: 10 to 40mA
Trigger pin format: 10 uS digital pulse
Sound frequency: 40 KHz
Echo pin output: 0V-VCC
Echo pin format: digital

How to use

Send a 10Us wide pulse (low to high) to the Trigger pin.
Monitor the ECHO pin.
When the ECHO pin goes HIGH, start a timer.
When the ECHO pin goes LOW, stop the timer and save the elapsed time.
Use the elapsed time in the following formula to get the distance in cm:

Distance (in cm) = (elapsed time * sound velocity (340 m/s)) / 100 / 2

We will see a code example later


Parts List

Name Link
Arduino Uno UNO R3 CH340G/ATmega328P, compatible for Arduino UNO
HY-SRF05 HY-SRF05 SRF05 Ultrasonic Ranging Module Ultrasonic Sensor
connecting wire Free shipping Dupont line 120pcs 20cm male to male + male to female and female to female jumper wire



arduino and HY-SRF05

arduino and HY-SRF05



VCC to +5V
GND to ground
TRIG to digital pin 12
ECHO to digital pin 13
const int TRIG_PIN = 12;
const int ECHO_PIN = 13;
void setup() 
  // initialize serial communication:
void loop()
  long duration, distanceCm, distanceIn;
  digitalWrite(TRIG_PIN, LOW);
  digitalWrite(TRIG_PIN, HIGH);
  digitalWrite(TRIG_PIN, LOW);
  duration = pulseIn(ECHO_PIN,HIGH);
  // convert the time into a distance
  distanceCm = duration / 29.1 / 2 ;
  distanceIn = duration / 74 / 2;
  if (distanceCm <= 0)
    Serial.println("Out of range");
    Serial.print("in: ");



Open the serial monitor and you will something like this depending how close the module is to an object

I was moving the sensor away from an object

4in, 10cm
3in, 9cm
4in, 10cm
4in, 10cm
4in, 10cm
4in, 10cm
4in, 12cm
4in, 12cm
4in, 12cm


ADXL337 accelerometer Arduino Uno example

In this article we connect an ADXL337 accelerometer to an Arduino Uno

The ADXL337 is a small, thin, low power, complete 3-axis accelerometer with signal conditioned voltage outputs. The product measures acceleration with a minimum full-scale range of ±3g. It can measure the static acceleration of gravity in tiltsensing applications, as well as dynamic acceleration resulting from motion, shock, or vibration.

The user selects the bandwidth of the accelerometer using the CX, CY, and CZ capacitors at the XOUT, YOUT, and ZOUTpins. Bandwidths can be selected to suit the application, with a range of 0.5 Hz to 1600 Hz for X and Y axes, and a range of 0.5 Hz to 550 Hz for the Z axis.


Parts List

Name Link
Arduino Uno UNO R3 CH340G/ATmega328P, compatible for Arduino UNO
ADXL337 3-axis ADXL337 GY-61 Replacement ADXL335 Module Analog Output Accelerometer
Connecting wire Free shipping Dupont line 120pcs 20cm male to male + male to female and female to female jumper wire


arduino and adxl337

arduino and adxl337



No libraries required – this is a sparkfun example

// Make sure these two variables are correct for your setup
int scale = 3; // 3 (±3g) for ADXL337, 200 (±200g) for ADXL377
void setup()
  // Initialize serial communication at 115200 baud
// Read, scale, and print accelerometer data
void loop()
  // Get raw accelerometer data for each axis
  int rawX = analogRead(A0);
  int rawY = analogRead(A1);
  int rawZ = analogRead(A2);
  // Scale accelerometer ADC readings into common units
  // Scale map depends on if using a 5V or 3.3V microcontroller
  float scaledX, scaledY, scaledZ; // Scaled values for each axis
  scaledX = mapf(rawX, 0, 675, -scale, scale); // 3.3/5 * 1023 =~ 675
  scaledY = mapf(rawY, 0, 675, -scale, scale);
  scaledZ = mapf(rawZ, 0, 675, -scale, scale);
  // Print out raw X,Y,Z accelerometer readings
  Serial.print("X: "); Serial.println(rawX);
  Serial.print("Y: "); Serial.println(rawY);
  Serial.print("Z: "); Serial.println(rawZ);
  // Print out scaled X,Y,Z accelerometer readings
  Serial.print("X: "); Serial.print(scaledX); Serial.println(" g");
  Serial.print("Y: "); Serial.print(scaledY); Serial.println(" g");
  Serial.print("Z: "); Serial.print(scaledZ); Serial.println(" g");
  delay(2000); // Minimum delay of 2 milliseconds between sensor reads (500 Hz)
// Same functionality as Arduino's standard map function, except using floats
float mapf(float x, float in_min, float in_max, float out_min, float out_max)
  return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;



Open the serial monitor and you will see something like this

X: 384
Y: 340
Z: 281

X: 0.41 g
Y: 0.02 g
Z: -0.50 g

X: 410
Y: 345
Z: 345

X: 0.64 g
Y: 0.07 g
Z: 0.07 g




Arduino Uno and HDC1080 humidity and temperature sensor

The HDC1080 is a digital humidity sensor with integrated temperature sensor that provides excellent measurement accuracy at very low power. The HDC1080 operates over a wide supply range, and is a low cost, low power alternative to competitive solutions in a wide range of common applications. The humidity and temperature sensors are factory calibrated.

Relative Humidity Accuracy ±2% (typical)
Temperature Accuracy ±0.2°C (typical)
Excellent Stability at High Humidity
14 Bit Measurement Resolution
100 nA Sleep Mode Current



This was connected an Arduino Uno

 Arduino connection  Module connection
 3v3 3v3
 SDA – A4  SDA
 SCL – A5  SCL



You will need to download the following library and install it from , this is the default example



#include <Wire.h>
#include "ClosedCube_HDC1080.h"
ClosedCube_HDC1080 hdc1080;
void setup()
Serial.println("ClosedCube HDC1080 Arduino Test");
// Default settings:
// - Heater off
// - 14 bit Temperature and Humidity Measurement Resolutions
Serial.print("Manufacturer ID=0x");
Serial.println(hdc1080.readManufacturerId(), HEX); // 0x5449 ID of Texas Instruments
Serial.print("Device ID=0x");
Serial.println(hdc1080.readDeviceId(), HEX); // 0x1050 ID of the device
void loop()
Serial.print("C, RH=");
void printSerialNumber() {
Serial.print("Device Serial Number=");
HDC1080_SerialNumber sernum = hdc1080.readSerialNumber();
char format[12];
sprintf(format, "%02X-%04X-%04X", sernum.serialFirst, sernum.serialMid, sernum.serialLast);





Open the serial monitor window and you should expect to see something like this

T=21.75C, RH=28.00%
T=21.60C, RH=28.21%
T=25.36C, RH=32.17%
T=27.87C, RH=43.27%
T=27.42C, RH=40.23%
T=26.90C, RH=32.15%
T=26.41C, RH=27.84%
T=26.00C, RH=25.77%
T=25.59C, RH=24.80%
T=25.15C, RH=24.43%
T=24.81C, RH=24.34%
T=24.45C, RH=24.47%
T=24.13C, RH=24.68%
T=23.82C, RH=24.89%
T=23.55C, RH=25.30%
T=23.26C, RH=25.72%
T=23.01C, RH=26.14%
T=22.71C, RH=26.64%
T=22.49C, RH=26.96%
T=22.28C, RH=27.27%



1PC 2.7 V to 5.5 V HDC1080 high precision temperature and humidity sensor humidity temperature module


Arduino Uno and BMP280 sensor example

BMP280 is an absolute barometric pressure sensor especially designed for mobile applications. The sensor module is housed in an extremely compact package. Its small dimensions and its low power consumption allow for the implementation in battery powered devices such as mobile phones, GPS modules or watches.

As its predecessor BMP180, BMP280 is based on Bosch’s proven Piezo-resistive pressure sensor technology featuring high accuracy and linearity as well as long term stability and high EMC robustness. Numerous device operation options offer highest flexibility to optimize the device regarding power consumption, resolution and filter performance. A tested set of default settings for example use case is provided to the developer in order to make design-in as easy as possible.


– Enhancement of GPS navigation (e.g. time-tofirst-fix improvement, dead-reckoning, slope detection)

– Indoor navigation (floor detection, elevator detection)

– Outdoor navigation, leisure and sports applications

– Weather forecast

– Health care applications (e.g. spirometry)

– Vertical velocity indication (e.g. rise/sink speed)

Parameter Technical data
Operation range (full accuracy) Pressure: 300…1100 hPa
Temperature: -40…85°C
Absolute accuracy
(Temp. @ 0…+65°C)
~ ±1 hPa
Relative accuracy
p = 700…900hPa
(Temp. @ +25…+40°C)
± 0.12 hPa (typical)
equivalent to ±1 m
Average current consumption (1 Hz data refresh rate) 2.74 μA, typical
(ultra-low power mode)
Average current consumption in sleep mode 0.1 μA
Average measurement time 5.5 msec
(ultra-low power preset)
Supply voltage VDDIO 1.2 … 3.6 V
Supply voltage VDD 1.71 … 3.6 V
Resolution of data Pressure: 0.01 hPa ( < 10 cm)
Temperature: 0.01° C
Temperature coefficient offset
(+25°…+40°C @900hPa)
± 0.12 hPa (typical)
equivalent to ±1 m
Interface I²C and SPI



This is a layout diagram using an adafruit part, my module had clearly marked SDA and SCL connections

In this example we will connect to an Arduino

arduino and bmp280

arduino and bmp280



This example requires and


This is a library for the BMP280 humidity, temperature & pressure sensor
Designed specifically to work with the Adafruit BMEP280 Breakout
These sensors use I2C or SPI to communicate, 2 or 4 pins are required
to interface.
Adafruit invests time and resources providing this open source code,
please support Adafruit andopen-source hardware by purchasing products
from Adafruit!
Written by Limor Fried & Kevin Townsend for Adafruit Industries.
BSD license, all text above must be included in any redistribution
#include <Wire.h>
#include <SPI.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_BMP280.h>
#define BMP_SCK 13
#define BMP_MISO 12
#define BMP_MOSI 11
#define BMP_CS 10
Adafruit_BMP280 bme; // I2C
//Adafruit_BMP280 bme(BMP_CS); // hardware SPI
//Adafruit_BMP280 bme(BMP_CS, BMP_MOSI, BMP_MISO, BMP_SCK);
void setup() {
Serial.println(F("BMP280 test"));
if (!bme.begin()) {
Serial.println("Could not find a valid BMP280 sensor, check wiring!");
while (1);
void loop() {
Serial.print("Temperature = ");
Serial.println(" *C");
Serial.print("Pressure = ");
Serial.println(" Pa");
Serial.print("Approx altitude = ");
Serial.print(bme.readAltitude(1013.25)); // this should be adjusted to your local forcase
Serial.println(" m");





Temperature = 27.65 *C
Pressure = 100592.44 Pa
Approx altitude = 61.17 m

Temperature = 28.72 *C
Pressure = 100589.25 Pa
Approx altitude = 61.44 m

Temperature = 29.31 *C
Pressure = 100590.25 Pa
Approx altitude = 61.35 m

Temperature = 29.70 *C
Pressure = 100588.21 Pa
Approx altitude = 61.53 m

Temperature = 30.01 *C
Pressure = 100581.49 Pa
Approx altitude = 62.09 m

Temperature = 28.95 *C
Pressure = 100601.21 Pa
Approx altitude = 60.44 m



1 piece I2C/SPI BMP280 3.3 Digital Barometric Pressure Altitude Sensor Module High Precision Atmospheric Module for Arduino