I would like to construct a device to alert me when the device is moved quickly & to ignore slow movement. When fast movement is detected a signal needs to light up an LED, sound an alarm & transmit a message via Bluetooth to my Android.
It should be as small & light as possible. I have purchased a Uno board, what would anyone suggest to complete the project? I think I need an accelerometer, a Bluetooth transceiver & an LED.
What do I need to filter out slow movements? Some sort of control circuit?
What suggestions does anyone have for an audible alarm?
Cheers
:~
Welcome to the forum.
Can you make a led blink with the Arduino Uno ? That is how to start with Arduino.
An accelerometer measures the acceleration, not the speed. You can calculate the speed, but that is inaccurate.
Can you tell more about the project ?
It is like a box that people carry ? That is something that is possible. If the box is handled gently, an accelerometer has low values, and if the box is handled rough, the accelerometer measures a lot of activity.
Thanks for the welcome Peter.
I’m waiting for delivery of the Uno so I haven’t made the LED blink. Just deciding on & buying parts at the moment.
The device will be mounted in a box that will normally be at rest. Sometimes it will move slowly, say 1 movement per second which I want to ignore. I want to be alerted when it moves 2-3 times a second like a tap tap motion. I don’t need to calculate speed but naturally an object moving 2-3 times per second (tap tap tap) will be moving faster than an object moving once per second before it comes back to it’s rest position.
You can detect the 'tap' with an accelerometer.
But it could be hard to determine how strong the 'tap' should be to be detected. That is something you have to experiment with.
Every modern accelerometer has 3 axis (x,y,z). You can calculate the resulting vector.
You can use an analog accelerometer to get a result very fast, but a digital accelerometer is more accurate (and more fun).
The best shops are www.sparkfun.com and www.adafruit.com and if you are willing to risk buying very cheap components, there is an overwhelming amount of sensors on Ebay.
A 20 dollar accelerometer doesn't have to be better than a 2 dollar accelerometer. Any cheap accelerometer is good for your project, as long as it have 3 axis.
Thanks Peter, looking for accelerometers now.
What is required for an alarm or some sound to activate? A speaker, amp, pre amp & sound/tone generator? Is there an Arduino module already available that does all this in one package that I should search for & if so what terminology do I search for?
A speaker or pieze element and a 100 ohm series resistor is often used.
That is the minimal basic.
You can go wild with audio, with mp3 shields, amplifiers and so on.
There are libraries that push the Arduino to its limits and can play music from an SD card without mp3 shield.
Have a look at Adafruit if you want a simple wave shield : Adafruit Wave Shield for Arduino Kit [v1.1] : ID 94 : $22.00 : Adafruit Industries, Unique & fun DIY electronics and kits
But you can start with the speaker and 100 ohm resistor and the Tone library : tone() - Arduino Reference
There is even a library that makes the speaker twice as loud (toneAC).
