4 August 2015

MT8870 DTMF - Dual Tone Multi Frequency Decoder

Project Description

We will be using an MT8870 DTMF module with an Arduino UNO to control a small servo motor in this project. The DTMF module gives the Arduino super-powers and allows you to control the Servo motor in so many ways. For example, this tutorial will show you how to control the servo motor using:
  • a YouTube Video
  • a voice recorder
  • A web application (Online tone generator)
  • A smart phone app (DTMF Pad)
  • A touch-tone phone to cell-phone call
All of these control methods will take advantage of the same exact Arduino code/sketch. But how???
The MT8870 DTMF decoder is quite a neat little module that allows you incorporate DTMF technology into your arduino projects. DTMF stands for Dual-Tone Multi-Frequency. DTMF tones are commonly associated with touch-tone phones and other telecommunication systems. When you press the number "1" on a touch-tone phone, two sine waves with frequencies: 697Hz and 1209Hz are combined to produce a unique DTMF signal which can be transmitted through the phone line. The MT8870 DTMF module can take this signal as an input, and decode it to produce a binary output.
 
 

 
The DTMF module does not care how you produce the DTMF tone. However, if it receives this tone, it will decode it. We can take advantage of this feature to supply the module with tones from different sources. The module has a 3.5mm port for line input. Providing you can connect your DTMF source to this line input in some way, it should work. I must warn you, however that this is a line input and NOT a microphone input. If you wanted to use a microphone, you will need to boost or amplify the signal before sending it to the DTMF module.
 
You will need the following parts for this project
 

Parts Required:

Software/Apps Required

Arduino Sketch


Upload the following sketch to the Arduino.
 

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/* ================================================================================================================================================== Project: MT8870 DTMF Servo sketch Author: Scott C Created: 4th August 2015 Arduino IDE: 1.6.4 Website: http://arduinobasics.blogspot.com/p/arduino-basics-projects-page.html Description: This project will allow you to control a Servo motor using an Arduino UNO and a MT8870 DTMF Module. The DTMF signal is received through the 3.5mm port of the DTMF module and is decoded. We will use the decoded output to control the position of the Servo. A SG-5010 Servo motor was used in this project. ===================================================================================================================================================== */ //This sketch uses the Servo library that comes with the Arduino IDE #include <Servo.h> //Global variables----------------------------------------------------------------------------------------- Servo SG5010; // The SG5010 variable provides Servo functionality int servoPosition = 0; // The servoPosition variable will be used to set the position of the servo byte DTMFread; // The DTMFread variable will be used to interpret the output of the DTMF module. const int STQ = 3; // Attach DTMF Module STQ Pin to Arduino Digital Pin 3 const int Q4 = 4; // Attach DTMF Module Q4 Pin to Arduino Digital Pin 4 const int Q3 = 5; // Attach DTMF Module Q3 Pin to Arduino Digital Pin 5 const int Q2 = 6; // Attach DTMF Module Q2 Pin to Arduino Digital Pin 6 const int Q1 = 7; // Attach DTMF Module Q1 Pin to Arduino Digital Pin 7 /*========================================================================================================= setup() : will setup the Servo, and prepare the Arduino to receive the MT8700 DTMF module's output. ========================================================================================================== */ void setup() { SG5010.attach(9); // The Servo signal cable will be attached to Arduino Digital Pin 9 SG5010.write(servoPosition); // Set the servo position to zero. //Setup the INPUT pins on the Arduino pinMode(STQ, INPUT); pinMode(Q4, INPUT); pinMode(Q3, INPUT); pinMode(Q2, INPUT); pinMode(Q1, INPUT); } /*========================================================================================================= loop() : Arduino will interpret the DTMF module output and position the Servo accordingly ========================================================================================================== */ void loop() { if(digitalRead(STQ)==HIGH){ //When a DTMF tone is detected, STQ will read HIGH for the duration of the tone. DTMFread=0; if(digitalRead(Q1)==HIGH){ //If Q1 reads HIGH, then add 1 to the DTMFread variable DTMFread=DTMFread+1; } if(digitalRead(Q2)==HIGH){ //If Q2 reads HIGH, then add 2 to the DTMFread variable DTMFread=DTMFread+2; } if(digitalRead(Q3)==HIGH){ //If Q3 reads HIGH, then add 4 to the DTMFread variable DTMFread=DTMFread+4; } if(digitalRead(Q4)==HIGH){ //If Q4 reads HIGH, then add 8 to the DTMFread variable DTMFread=DTMFread+8; } servoPosition = DTMFread * 8.5; //Set the servoPosition varaible to the combined total of all the Q1 to Q4 readings. Multiply by 8.5 to amplify the servo rotation. } SG5010.write(servoPosition); //Set the servo's position according to the "servoPosition" variable. }


 
 
 

Fritzing Sketch


Connect the Arduino to the MT8870 DTMF module, and to a Servo.
Use the following Fritzing sketch as a guide.
 
(Click the image above to enlarge it)



Discussion


You will need to connect a cable from the DTMF module's 3.5mm port to that of your smart phone, computer, voice recorder or any other DTMF source of your choice.
 

 

When you power up your Arduino, the Servo motor should turn all the way to the left to it's zero position. Once the DTMF module receives a DTMF signal, it will identify the relevant frequecies as described in the table at the beginning of this tutorial, and produce a binary like output. You will notice the DTMF module's onboard LEDs light up when a tone is detected. Onboard LED (D5) will turn on for the length of the DTMF tone it just received, and turn off when the tone has stopped. On the other hand, the onboard LEDs (D1 to D4) will light up depending on the tone received, and will remain lit until the module receives another tone. The onboard LEDs are a visual representation of the voltages applied to the DTMF module's pins (Q1 to Q4, and STQ). Q1 matches D1, Q2 matches D2 etc etc. and STQ matches D5.
 
You will notice that there are two STQ pins on the DTMF module. The STQ pin that is closest to Q4 will only go high when a DTMF tone is detected, and will remain high for the duration of the tone. The other STQ pin is the exact opposite. It will switch LOW when a tone is received and remain LOW for the duration of the tone. When there is no tone, this STQ pin will remain HIGH. The table below provides a summary of the DTMF module outputs, with a blue box representing a voltage applied to that pin (HIGH), whereas a black box indicates no voltage applied (LOW).


 
In order to follow this project, you need a source of DTMF tones. You can produce DTMF tones using a touch-tone phone, or through the use of a DTMF Pad app. If you are feeling creative, you can create a DTMF song/tune like the one I posted on YouTube. You can see the video below:
 

 
As you can see from the video, I also recorded the DTMF tune onto a voice recorder, and was able to control the servo that way. If you are not feeling creative, you can visit this website to create DTMF tones from your browser.

Concluding comments


This project was very fun, and shows some novel ways to control your Arduino. After completing the project, I realised that I could use this module to alert me when new emails or messages arrive on my phone or computer. If you have the ability to change the email or message notification sound to a DTMF tone, you should be able to get the module and Arduino to respond accordingly. Oh well, maybe I'll save that project for another day.
 
If this project helped you in anyway or if you use my code within your project, please let me know in the comments below. I would be interested to see what you did.


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18 July 2015

NeoPixel Heart Beat Display


Project Description


In this project, your heart will control a mesmerising LED sequence on a 5 metre Neopixel LED strip with a ws2812B chipset. Every heart beat will trigger a LED animation that will keep you captivated and attached to your Arduino for ages. The good thing about this project is that it is relatively easy to set up, and requires no soldering. The hardest part is downloading and installing the FastLED library into the Arduino IDE, but that in itself is not too difficult. The inspiration and idea behind this project came from Ali Murtaza, who wanted to know how to get an LED strip to pulse to his heart beat.
 
Have a look at the video below to see this project in action.
 
 
 

The Video


 


 
 

Parts Required:


 

Power Requirements

Before you start any LED strip project, the first thing you will need to think about is POWER. According to the Adafruit website, each individual NeoPixel LED can draw up to 60 milliamps at maximum brightness - white. Therefore the amount of current required for the entire strip will be way more than your Arduino can handle. If you try to power this LED strip directly from your Arduino, you run the risk of damaging not only your Arduino, but your USB port as well. The Arduino will be used to control the LED strip, but the LED strip will need to be powered by a separate power supply. The power supply you choose to use is important. It must provide the correct voltage, and must able to supply sufficient current.
 

Operating Voltage (5V)

The operating voltage of the NeoPixel strip is 5 volts DC. Excessive voltage will damage/destroy your NeoPixels.

Current requirements (9.0 Amps)

OpenLab recommend the use of a 5V 10A power supply. Having more Amps is OK, providing the output voltage is 5V DC. The LEDs will only draw as much current as they need. To calculate the amount of current this 5m strip can draw with all LEDs turned on at full brightness - white:

30 NeoPixel LEDs x 60mA x 5m = 9000mA = 9.0 Amps for a 5 metre strip.

Therefore a 5V 10A power supply would be able to handle the maximum current (9.0 Amps) demanded by a 5m NeoPixel strip containing a total of 150 LEDs.
 
 


Arduino Libraries and IDE


Before you start to hook up any components, upload the following sketch to the Arduino microcontroller. I am assuming that you already have the Arduino IDE installed on your computer. If not, the IDE can be downloaded from here.
 
The FastLED library is useful for simplifying the code for programming the NeoPixels. The latest "FastLED library" can be downloaded from here. I used FastLED library version 3.0.3 in this project.
 
If you have a different LED strip or your NeoPixels have a different chipset, make sure to change the relevant lines of code to accomodate your hardware. I would suggest you try out a few of the FastLED library examples before using the code below, so that you become more familiar with the library, and will be better equipped to make the necessary changes. If you have a 5 metre length of the NeoPixel 30 LED/m strip with the ws2812B chipset, then you will not have to make any modification below.
 

ARDUINO CODE:


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/* ================================================================================================ Project: NeoPixel Heart Beat Display Neopixel chipset: ws2812B (30 LED/m strip) Author: Scott C Created: 8th July 2015 Arduino IDE: 1.6.4 Website: http://arduinobasics.blogspot.com/p/arduino-basics-projects-page.html Description: This sketch will display a heart beat on a 5m Neopixel LED strip. Requires a Grove Ear-clip heart rate sensor and a Neopixel strip. This project makes use of the FastLED library: http://fastled.io/ You may need to modify the code below to accomodate your specific LED strip. See the FastLED library site for more details. ================================================================================================== */ //This project needs the FastLED library - link in the description. #include "FastLED.h" //The total number of LEDs being used is 150 #define NUM_LEDS 150 // The data pin for the NeoPixel strip is connected to digital Pin 6 on the Arduino #define DATA_PIN 6 //Attach the Grove Ear-clip heart rate sensor to digital pin 2 on the Arduino. #define EAR_CLIP 2 //Initialise the LED array CRGB leds[NUM_LEDS]; //Initialise the global variables used to control the LED animation int ledNum = 0; //Keep track of the LEDs boolean beated = false; //Used to identify when the heart has beated int randomR = 0; //randomR used to randomise the fade-out of the LEDs //================================================================================================ // setup() : Is used to initialise the LED strip //================================================================================================ void setup() { FastLED.addLeds<NEOPIXEL,DATA_PIN>(leds, NUM_LEDS); //Set digital pin 2 (Ear-clip heart rate sensor) as an INPUT pinMode(EAR_CLIP, INPUT); } //================================================================================================ // loop() : Take readings from the Ear-clip sensor, and display the animation on the LED strip //================================================================================================ void loop() { //If the Ear-clip sensor moves from LOW to HIGH, call the beatTriggered method if(digitalRead(EAR_CLIP)>0){ //beatTriggered() is only called if the 'beated' variable is false. //This prevents multiple triggers from the same beat. if(!beated){ beatTriggered(); } } else { beated = false; //Change the 'beated' variable to false when the Ear-clip heart rate sensor is reading LOW. } //Fade the LEDs by 1 unit/cycle, when the heart is at 'rest' (i.e. between beats) fadeLEDs(5); } //================================================================================================ // beatTriggered() : This is the LED animation sequence when the heart beats //================================================================================================ void beatTriggered(){ //Ignite 30 LEDs with a red value between 0 to 255 for(int i = 0; i<30; i++){ //The red channel is randomised to a value between 0 to 255 leds[ledNum].r=random8(); FastLED.show(); //Call the fadeLEDs method after every 3rd LED is lit. if(ledNum%3==0){ fadeLEDs(5); } //Move to the next LED ledNum++; //Make sure to move back to the beginning if the animation falls off the end of the strip if(ledNum>(NUM_LEDS-1)){ ledNum=0; } } //Ignite 20 LEDS with a blue value between 0 to 120 for(int i = 0; i<20; i++){ //The blue channel is randomised to a value between 0 to 120 leds[ledNum].b=random8(120); FastLED.show(); //Call the fadeLEDs method after every 3rd LED is lit. if(ledNum%3==0){ fadeLEDs(5); } //Move to the next LED ledNum++; //Make sure to move back to the beginning if the animation falls off the end of the strip if(ledNum>(NUM_LEDS-1)){ ledNum=0; } } //Change the 'beated' variable to true, until the Ear-Clip sensor reads LOW. beated=true; } //================================================================================================ // fadeLEDs() : The fading effect of the LEDs when the Heart is resting (Ear-clip reads LOW) //================================================================================================ void fadeLEDs(int fadeVal){ for (int i = 0; i<NUM_LEDS; i++){ //Fade every LED by the fadeVal amount leds[i].fadeToBlackBy( fadeVal ); //Randomly re-fuel some of the LEDs that are currently lit (1% chance per cycle) //This enhances the twinkling effect. if(leds[i].r>10){ randomR = random8(100); if(randomR<1){ //Set the red channel to a value of 80 leds[i].r=80; //Increase the green channel to 20 - to add to the effect leds[i].g=20; } } } FastLED.show(); }


 

NeoPixel Strip connection

The NeoPixel strip is rolled up when you first get it. You will notice that there are wires on both sides of the strip. This allows you to chain LED strips together to make longer strips. The more LEDs you have, the more current you will need. Connect your Arduino and power supply to the left side of the strip, with the arrows pointing to the right. (i.e. the side with the "female" jst connector).
 



NeoPixel Strip Wires

There are 5 wires that come pre-attached to either side of the LED strip.
 

 
You don't have to use ALL FIVE wires, however you will need at least one of each colour: red, white & green.
 

 

Fritzing sketch

The following diagram will show you how to wire everything together
 
(click to enlarge)

Arduino Power considerations

Please note that the Arduino is powered by a USB cable.
If you plan to power the Arduino from your power supply, you will need to disconnect the USB cable from the Arduino FIRST, then connect a wire from the 5V line on the Power supply to the VIN pin on the Arduino. Do NOT connect the USB cable to the Arduino while the VIN wire is connected.
 

 

Large Capacitor

Adafruit also recommend the use of a large capacitor across the + and - terminals of the LED strip to "prevent the initial onrush of current from damaging the pixels". Adafruit recommends a capacitor that is 1000uF, 6.3V or higher. I used a 4700uF 16V Electrolytic Capacitor.
 

 

Resistor on Data Pin

Another recommendation from Adafruit is to place a "300 to 500 Ohm resistor" between the Arduino's data pin and the data input on the first NeoPixel to prevent voltage spikes that can damage the first pixel. I used a 330 Ohm resistor.
 

 

Grove Ear-clip heart rate sensor connection

The Grove Base shield makes it easy to connect Grove modules to the Arduino. If you have a Grove Base shield, you will need to connect the Ear-clip heart rate sensor to Digital pin 2 as per the diagram below.
 

 

Completed construction

Once you have everything connected, you can plug the USB cable into the Arduino, and turn on the LED power supply. Attach the ear-clip to your ear (or to your finger) and allow a few seconds to allow the sensor to register your pulse. The LED strip will light up with every heart beat with an animation that moves from one end of the strip to the other in just three heart beats. When the ear-clip is not connected to your ear or finger, the LEDs should remain off. However, the ear clip may "trigger" a heart beat when opening or closing the clip.
 
Here is a picture of all the components (fully assembled).
 


Concluding comments


This very affordable LED strip allows you to create amazing animations over a greater distance. I thought that having less LEDs per metre would make the animations look "jittery", but I was wrong, they look amazing. One of the good things about this strip is the amount of space between each Neopixel, allowing you to easily cut and join the strip to the size and shape you need.
 
This LED strip is compatible with the FastLED library, which makes for easy LED animation programming. While I used this LED strip to display my heart beat, you could just as easily use it to display the output of any other sensor attached to the Arduino.
 



If you like this page, please do me a favour and show your appreciation :

 
Visit my ArduinoBasics Google + page.
Follow me on Twitter by looking for ScottC @ArduinoBasics.
I can also be found on Pinterest and Instagram.
Have a look at my videos on my YouTube channel.


 
 
             

 
This project would not have been possible without OpenLab's collaborative effort.
Please visit their site for more cool projects.



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