How to Use Accelerometers on the Arduino - Ultimate Guide to the Arduino #42

Summary

The video introduces the 'Three in One Smart Car and IoT, Learning Kit' from SunFounder, an all-inclusive electronics kit designed for mastering Arduino. It includes an Arduino, sensors, modules, and tools for building various projects, such as a remote-controlled smart car, IoT temperature and humidity monitoring, and a plant monitor. The script also covers the ADXL345 accelerometer, detailing its functionality, wiring, and programming with the Arduino, showcasing raw data and G's conversion, and highlighting SunFounder's extensive support for STEM and IoT projects.

Takeaways

• 🚗 The 'Three in One Smart Car and IoT Learning Kit' from SunFounder is an all-inclusive electronics kit designed for mastering Arduino.
• 🔧 The kit includes an Arduino, 22 different sensors and modules, breadboards, jumper wires, and other necessary components for building various projects.
• 🤖 Learn robotics by constructing a remote-controlled smart car that can be operated with an infrared remote or programmed to drive autonomously and avoid obstacles.
• 🌡️ Explore IoT with a project that monitors temperature, humidity, and light levels in a room via a smartphone app.
• 🌱 Build a plant monitor to track temperature, humidity, light intensity, and soil moisture, displaying this information on a smartphone for remote plant care.
• 📈 Accelerometers, like the ADXL345, are used to detect motion and orientation and can be used in various applications, including waking up an Arduino or detecting device falls.
• 🔢 The ADXL345 can measure both static (from gravity) and dynamic (from motion) acceleration and communicates with the Arduino over SPI or I2C.
• 📊 Accelerometers measure acceleration in units of meters per second squared or G's, with 1G being equivalent to 9.8 m/s², the acceleration due to gravity.
• 🔍 The ADXL345 outputs separate acceleration measurements for each axis (x, y, z) and uses changes in capacitance to calculate acceleration values.
• 🛠️ Different accelerometers have varying sensitivities, measured in G's, with ranges from ±1G to ±250G, allowing for detection of subtle to significant forces.
• 🔧 The ADXL345 has four selectable sensitivity ranges: ±2G, ±4G, ±8G, and ±16G, and requires a specific library for programming and interpreting its data.

Q & A

What is the 'Three in One Smart Car and IoT Learning Kit' from SunFounder?

The 'Three in One Smart Car and IoT Learning Kit' from SunFounder is a comprehensive electronics kit designed for learning to master the Arduino platform. It includes an Arduino, 22 different sensors and modules, breadboards, jumper wires, and other necessary components to build various fun and educational projects.

What can you learn from the kit about robotics?

With the kit, you can learn about robotics by building a remote-controlled smart car that can be operated with an infrared remote controller, drive autonomously, avoid obstacles, or follow a line.

How does the kit help in learning about the Internet of Things (IoT)?

The kit includes an IoT project that allows you to monitor temperature, humidity, and light levels of a room from an app on your smartphone, and build a plant monitor that tracks and displays temperature, humidity, light intensity, and soil moisture.

What is an accelerometer and how is it used in the context of the ADXL 345?

An accelerometer is a sensor used to detect motion and orientation. The ADXL 345, which is featured in the script, can be used to wake up an Arduino when tapped or picked up, detect falling devices, and is used in smartphones to turn off the display after a period of inactivity.

How does the ADXL 345 communicate with the Arduino?

The ADXL 345 can communicate with the Arduino over SPI (Serial Peripheral Interface) or I2C (Inter-Integrated Circuit). The script demonstrates using I2C for communication.

What are the two common units of acceleration measurement mentioned in the script?

The two common units of acceleration measurement mentioned are meters per second squared and G's, with 1G being equivalent to the acceleration due to gravity, which is 9.8 meters per second squared.

How does the ADXL 345 measure acceleration?

The ADXL 345 measures acceleration by detecting changes in capacitance along each axis. It has a tiny plate suspended between two micro springs that can move back and forth. When the sensor accelerates, the distance between the plates changes, altering the capacitance, which the sensor measures to calculate the acceleration value.

What are the different sensitivity ranges of the ADXL 345?

The ADXL 345 has four different sensitivity ranges: plus or minus 2G, plus or minus 4G, plus or minus 8G, and plus or minus 16G.

How do you convert the raw sensor readings from the ADXL 345 to G's?

To convert the raw sensor readings to G's, you multiply the two's complement output by the scale factor provided in the datasheet for the selected sensitivity range.

What is the purpose of the SparkFun ADXL 345 library mentioned in the script?

The SparkFun ADXL 345 library is used to interface with the ADXL 345 sensor from within an Arduino sketch. It provides useful functions to initialize the sensor, set its range, and read acceleration data from the sensor.

How can you calibrate the ADXL 345 sensor if the readings seem off?

If the ADXL 345 sensor readings seem off, you can calibrate it by following a tutorial provided by SparkFun, which is mentioned in the script and can be found on their website.

What additional components does SunFounder provide for Arduino and Raspberry Pi projects?

SunFounder provides a wide selection of STEM, robotics, and IoT kits, as well as various useful sensors and modules for Arduino and Raspberry Pi projects. They also offer online tutorials with wiring diagrams and example code for every product.

Outlines

00:00

🛠️ Arduino Smart Car and IoT Kit Overview

The script introduces the 'three in one' smart car and IoT learning kit from SunFounder, an all-inclusive electronics kit designed for mastering the Arduino platform. It includes an Arduino UNO, a variety of sensors and modules, solderless breadboards, jumper wires, and other necessary components to create engaging projects. The kit facilitates learning about robotics through building a remotely controlled smart car with obstacle avoidance capabilities and line-following features. It also covers IoT by enabling the creation of projects that monitor environmental conditions and plant health through smartphone apps. The video encourages viewers to order the kit via a provided link and mentions the exploration of accelerometers, specifically the ADXL 345, in subsequent content.

05:01

📏 Understanding Accelerometers and ADXL 345

This paragraph delves into the functionality of accelerometers, which are sensors used to detect motion and orientation. The ADXL 345 is highlighted as an example, with a focus on its ability to be woken up by tapping or picking up and to detect falling motions, similar to its applications in computers and smartphones. The ADXL 345's breakout module from Adafruit is described, detailing its pin functions, including power supply options (3.3 volts or 5 volts), chip select for SPI, and interrupt pins. The communication protocols available for the ADXL 345, such as SPI and I2C, are mentioned, with I2C being the chosen method for the video. The concept of acceleration, both static due to gravity and dynamic due to motion, is explained, along with the units used to measure it, such as meters per second squared and G's.

10:02

🔍 Connecting and Programming the ADXL 345

The script provides a step-by-step guide on connecting the ADXL 345 accelerometer to an Arduino using I2C communication, with specific pin connections detailed. It also outlines the process of programming the Arduino to interact with the accelerometer, including the installation of the SparkFun ADXL 345 library. The provided sketch demonstrates how to initialize the sensor, set its sensitivity range, and read raw acceleration values from each axis. The script explains the two's complement format of the raw data and how to convert these values to G's using scale factors from the datasheet. Additionally, it discusses the sensitivity ranges of accelerometers and how to select the appropriate range for different applications.

15:03

📊 Interpreting Accelerometer Data in G's

This section of the script focuses on converting the raw accelerometer readings into meaningful measurements in G's. It explains the use of a switch-case statement to select the appropriate scale factor based on the chosen sensitivity range of the ADXL 345. The sketch provided in the script demonstrates how to perform this conversion and output the results in milligs, with an option to adjust for G's by dividing by 1000. The script also touches on the potential need for sensor calibration if readings are inconsistent and references a SparkFun tutorial for calibrating the ADXL 345. Finally, it teases the topic of gyroscopes for future videos and promotes SunFounder as a reliable source for Arduino and Raspberry Pi components, kits, and tutorials.

Keywords

💡Arduino

Arduino is an open-source electronics platform based on easy-to-use hardware and software. It is the central theme of the video as the kit is designed to help users master the Arduino. The Arduino board is used to build various projects, including a smart car and IoT devices, demonstrating its versatility and importance in the script.

💡Sensors

Sensors are devices that detect and respond to some type of input from the environment. In the video, different sensors are included in the kit to help users learn about various aspects of electronics, such as motion, orientation, temperature, humidity, and light. They are integral to the projects described, like the accelerometer and the plant monitor.

💡IoT (Internet of Things)

IoT refers to the network of physical devices, vehicles, and other items embedded with sensors, software, and connectivity that enables these objects to collect and exchange data. The video discusses an IoT project that allows users to monitor environmental conditions via a smartphone app, illustrating the practical application of IoT in everyday life.

💡ADXL345

The ADXL345 is a specific type of accelerometer mentioned in the script, used to detect motion and orientation. It is an example of a sensor that can be integrated with the Arduino to create interactive projects. The video explains how this sensor works and how it can be used in projects to measure acceleration along different axes.

💡SPI (Serial Peripheral Interface)

SPI is a synchronous serial communication interface specification used for short distance communication, primarily in embedded systems. The script mentions SPI as a communication protocol that the ADXL345 can use to interface with the Arduino, although I2C is used in the video's example.

💡I2C (Inter-Integrated Circuit)

I2C is a multi-master, single-bus, serial computer bus invented by Philips Semiconductor. It is one of the most popular methods for connecting the ADXL345 to the Arduino in the video. It allows for communication between the microcontroller and the sensor with only two wires, simplifying the connection process.

💡Acceleration

Acceleration is the rate of change of velocity of an object. The video explains that accelerometers, like the ADXL345, measure both static and dynamic acceleration. The script uses the concept of acceleration to describe how the sensor can detect motion and the effects of gravity on the sensor's readings.

💡Two's Complement

Two's complement is a mathematical representation of signed numbers in binary form. The video explains that the raw sensor readings from the ADXL345 are in two's complement format, which is necessary to understand when converting the raw data into meaningful acceleration measurements in G's or milligs.

💡Calibration

Calibration is the process of adjusting a system or instrument to ensure that its output is accurate and reliable. The script mentions that if sensor readings seem off, the ADXL345 might need to be calibrated, indicating the importance of this process in achieving accurate measurements.

💡SunFounder

SunFounder is a company mentioned in the script as a source for sensors, modules, and other parts for Arduino and Raspberry Pi projects. The video promotes their learning kit and highlights their offerings, including STEM, robotics, and IoT kits, as well as their online tutorials and free shipping policy.

Highlights

The 'Three in One Smart Car and IoT, Learning Kit' from SunFounder is an all-inclusive electronics kit designed for mastering Arduino.

The kit includes an Arduino, 22 different sensors and modules, breadboards, jumper wires, and other necessary components for project building.

Learn robotics by constructing a remote-controlled smart car that can be operated with an infrared remote or autonomously to avoid obstacles or follow a line.

Explore IoT through a project that monitors room temperature, humidity, and light levels using a smartphone app.

Build a plant monitor that tracks temperature, humidity, light intensity, and soil moisture, displaying this information on a smartphone for remote plant care.

The kit is highly rated for its engaging projects and comprehensive learning experience in electronics and programming.

Accelerometers, such as the ADXL 345, are used to detect motion and orientation and can be utilized to trigger actions in response to movement or changes in position.

The ADXL 345 can be interfaced with the Arduino over SPI or I2C, offering flexibility in project design.

The ADXL 345 has multiple pins for power, interrupts, and data output, supporting both SPI and I2C communication.

Acceleration is measured in meters per second squared or G's, with 1G equal to the acceleration due to gravity at 9.8 m/s².

The ADXL 345 outputs separate acceleration measurements for the X, Y, and Z axes, detecting both static and dynamic acceleration.

ADXL 345 measures acceleration by detecting changes in capacitance between suspended plates, translating movement into electrical signals.

Different accelerometers offer varying sensitivity ranges, from ±1G to ±250G, suitable for detecting subtle vibrations or significant impacts.

The ADXL 345 has four selectable sensitivity ranges: ±2G, ±4G, ±8G, and ±16G, allowing for customization based on the application's needs.

Programming the ADXL 345 involves using a library, such as the SparkFun ADXL 345 library, which simplifies communication and data retrieval.

Raw accelerometer data is in two's complement format, requiring conversion to G's using scale factors provided in the datasheet.

SunFounder is a recommended source for Arduino and Raspberry Pi components, offering a wide selection of STEM, robotics, and IoT kits, along with detailed tutorials and free shipping.

Transcripts

the three in one smart car and iot

learning kit from Sun founder is a

Hands-On all included Electronics kit

that is perfect for anyone who wants to

learn how to master the Arduino

the kit comes with an Arduino 22

different sensors and modules

thread boards jumper wires and

everything else you need to build a

bunch of fun and interesting projects

learn about robotics by building a

remote controlled smart car that can be

controlled with an infrared remote

controller

or drive on its own and avoid obstacles

or Follow The Line

learn about the internet of things with

a project that lets you monitor the

temperature humidity and light level of

a room from an app on your smartphone

[Music]

and build a plant monitor that tracks

the temperature humidity light intensity

and soil moisture

and displays it on your smartphone so

you can keep your plants water remotely

it's a super cool kit and I had lots of

fun building all the projects in it so

click the link in the description below

to order the kit from some founder

foreign

[Music]

we're going to learn about

accelerometers

accelerometers are used to detect motion

and orientation

you can use an accelerometer to wake up

an Arduino when it's tapped or picked up

by someone

they can also detect when a device is

falling

computers have accelerometers to turn

off the hard drive if it's dropped

they're also used in smartphones to turn

off the display after it hasn't been

moved in a while

the accelerometer we're going to look at

is the adxl 345

mine is a breakout module from Adafruit

this is the sensor chip right here

these are directional arrows that show

you where each axis points

the x-axis points in this direction

the y-axis points in this direction

and the z-axis points up

the adxl 345 can communicate with the

Arduino over SPI and i2c

in this video we're going to use i2c but

SPI is an option if you want to use it

up here at the top we have the VN pin

where the 5 volt power connects

one down from that is the 3.3 volt pin

you can power the adxl345 with either

3.3 volts or 5 volts

this is where the 3.3 volt power source

would connect

here's the ground pin

this is the Cs pin or chip select pin

for connecting it with SPI

the adxl 345 has two internet pins

N1 and N2

these can be used to trigger Hardware

interrupts on the Arduino

this is the sdo or slave data output pin

it functions the same as a miso pin

which transmits data from the sensor to

the Arduino over SPI

thank you now we have the two i2c pins

SDA and scl

the SDA pin doubles as the most C pin

for SPI

and the scl pin doubles as the scrk PIN

for SPI

acceleration is the rate of increase or

decrease of velocity

when you're driving in your car and you

step on the gas

your car has a positive acceleration

when you step on the brakes it has a

negative acceleration

accelerometers measure both static

acceleration and dynamic acceleration

static acceleration is caused by forces

like gravity

Dynamic acceleration is caused by forces

of motion like the acceleration from a

car speeding up or slowing down

two common units of acceleration are

meters per second squared and G's

1G is defined as the rate of

acceleration of gravity

which is 9.8 meters per second squared

the adxl 345 output separate

acceleration measurements for each axis

x y and z

the adxl345 measures acceleration by

detecting changes in capacitance

along each axis there's a tiny plate

suspended between two micro Springs they

can move back and forth

the mobile plate and the fixed plate are

charged

so an electric field is formed between

them

when the accelerometer is at rest the

electrical field between the plates is

constant

when the sensor accelerates the mobile

plate moves and the distance between the

plates changes

capacitance is a function of the

distance between two charge plates

so when the distance between the plates

changes

the electrical field between the plates

also changes

the sensor measures this changing

capacitance and calculates an

acceleration value

there are a few different kinds of

accelerometers you can get for the

Arduino

the main difference between them is

sensitivity

an accelerometer sensitivity is usually

provided in G's

some accelerometers can measure

acceleration between plus or minus 1G

other accelerometers can measure

acceleration up to plus or minus 250 G's

the smaller the acceleration range the

more sensitive the sensor

to detect small taps or vibrations you

would probably want an accelerometer

with a range of about 2gs

to detect something much stronger like a

rocket launcher a collision

you'd probably want to range closer to

250 G's

the adxl 345 has four different ranges

that you can select

plus or minus two G's plus or minus 4

G's plus or minus 8 G's and plus or

minus 16 G's

in the sketch we're going to use in a

minute you'll be able to set the

sensitivity

now let's connect the accelerometer to

the Arduino and take a look at the raw

values it provides

we're going to connect the accelerometer

with i2c so the wiring is pretty simple

ground connects to ground

and VCC connects to 5 volts

the SDA pin of the accelerometer

connects to analog pin A4 on the Arduino

and the scl pin in the accelerometer

connects to analog pin A5 on the Arduino

to program it we're going to need a

library

SparkFun has a great one with a lot of

useful functions

you can download it from this link

once you get that installed we can take

a look at the sketch

this sketch will output The Rock

accelerometer readings to the serial

monitor

the first thing we do is include the

SparkFun adxl 345 library with a hash

include

sparkphone underscore adxl345.h

next we create an object called adxl

which is a member of the adxl 345 class

we set that object equal to the function

adxl345.

the adxl 345 function configures the

communication mode the sensor we use to

talk to the Arduino

when there are no arguments passed to

the function as in this case

the sensor will use ITC to communicate

with the Arduino

if you're using SPI though put the

number 10 in here

we're using i2c so we can leave this

empty

now we declare a variable called range

this will store the sensitivity range we

want the adxl 345 to have

it can be either 2 4 8 or 16 G's

in the setup section we initialize the

serial monitor with serial begin 9600

now we initialize the adxl 345 with the

function power on

this function is applied to the adxl

object which we created up here

next we call the set range setting

function to set the sensitivity range of

the sensor

we pass out the range variable which

stores the range setting we defined when

we declared it

that's all the setup we needed to do

in the loop section the first thing we

have to do is declare some variables

that will hold the sensor readings

the adxl345 outputs separate

acceleration measurements for each axis

so we need a unique variable for each

axis

here I've declared three int variables x

y and z

next we get the sensor readings from the

accelerometer with the read Excel

function

the arguments are the variables that

hold the axis measurements

it doesn't matter what you name these

variables

the only thing that matters is the order

that they're entered into the function

the x-axis values will be stored in the

variable you put in the first parameter

the y-axis values will be stored in the

variable in the second parameter

and the z-axis values will be stored in

the variable you put as the third

parameter

now all we have to do is print the

variables

it'll be easier to see if we print all

the axes on one line

so I print in x equals with serial print

then I print the X variable

same thing for the Y and Z variables

print a y

then print the Y variable

and a z then print the Z variable

the Z variable is the last thing we

print on the line so we use serial print

line

then we delay 250 milliseconds to slow

down the output a bit

okay let's check this out

I've got my adxl 345 connected to my

Arduino

I also attached the sensor to a block of

wood so it's easier to see which axis is

which

you can see the sensor is outputting

values close to zero for the X and Y

axes

but the z-axis is outputting a value

around 230.

the force of gravity is creating an

acceleration vector along the z-axis

if I turn the sensor so that the y-axis

is perpendicular to the ground it'll

measure the acceleration from Gravity

along the y-axis

of course you can also create

acceleration yourself

watch the values of the X and Y axes

when I move the sensor around

these values aren't like other raw ADC

values we've seen when we read voltages

those values were always between 0 and

10 23.

the numbers you see here are in two's

complement format

two's complement is a way to represent

signed or negative numbers in binary

we can convert these two's complement

values to G's

with the conversion factors in the

datasheet

in the specifications table on page 3

there's a section called sensitivity

this section has the scale factors for

each sensitivity range

to get the acceleration readings in G's

we need to multiply the sensors two's

complement output by one of these scale

factors

each sensitivity range has a different

scale factor

this is the scale factor for the plus or

minus 2G sensitivity range

here's the scale factor when the range

is plus or minus 4 G's

eight G's

and 16 G's

now let's look at a sketch that outputs

the accelerometer readings in G's

foreign

actually this sketch is going to Output

the sensor readings in milligs

if you want the output in G's though

divide the millig's reading by 1000.

the first half of the sketch is the same

as the raw data sketch

we include the smartphone adxl 345

Library

create the adxl object

and configure i2c communication

Define the range variable

initialize the serial monitor

initialize the sensor

and set the range

in the loop we still declare X Y and Z

variables

and get the readings for each axis with

the read Excel function

now we convert the raw sensor readings

to G's

by multiplying the raw sensor readings

by the scale factor

the scale factor is going to be

different depending on which range

setting we choose

so this is a good place for a switch

case statement

we can use the switch statement and put

the range variable as the condition

case statement will Define what happens

when the range is set to 2 4 8 or 16 G's

when the range variable is equal to 2

the code in the first case will be

executed

the scale factor for 2G sensitivity is

3.9

so we have to multiply the output from

each axis by 3.9

then we have the break keyword so the

program exits the case

now we have case statements for all the

other possible values of the range

variable

when the range is set to 4Gs

the scale factor is 7.8

so we multiply each axis output by 7.8

when the range is set to AGS

the scale factor is 15.6

so we multiply all three axis variables

by 15.6

and when the range is set to 16 G's

the scale factor is 31.2 so we have to

multiply everything by 31.2

then we have a default statement at the

end

in case the range variable is set equal

to something different than 2 4 8 or 16.

the default code prints a line that says

please specify a range of 2 4 8 or 16

G's

now we print the X Y and Z variables to

the serial monitor

we print some text that says x equals

then print the X variable

we print some text that says y equals

and print the Y variable

same thing for Z

and print line the Z variable

then we delay for 250 milliseconds

let's take a look at how this works

so now the acceleration readings from

each axis are in milligs instead of

two's complement

the z-axis value is around 910 milligs

that's pretty close to 1G which is the

acceleration due to gravity

if your sensor readings seem a bit off

your sensor might need to be calibrated

there's a good SparkFun tutorial that

shows you how to calibrate an adxl345

visit this link to check it out

accelerometers measure acceleration

along the X Y and Z axes

but in the next video we're going to

look at gyroscopes which measure

rotation around the X Y and Z axes

[Music]

Sun founder is my go-to source for

sensors modules and other parts for the

Arduino and Raspberry Pi

they have a huge selection of stem

Robotics and iot kits and lots of useful

sensors and modules

every product has an online tutorial

with wiring diagrams and example code

they also offer free shipping on all

orders with no minimum give them a try

at

www.sunfounder.com next time you need to

order some parts