Advice 1: How to connect microphone to Arduino

Connect the module with sound sensor (microphone) to the Arduino.
Module with microphone
You will need
  • - Arduino;
  • module with electret capsule microphone CMA-4544PF-W;
  • - connecting wires.
Electret microphone CMA-4544PF-W, which is the basis of the module that responds to sound waves with frequencies from 20 Hz to 20 kHz. The microphone is omnidirectional, i.e., sensitive to sound coming from all directions, with a sensitivity of -44 dB. Learn more about the device and principle of operation of electret microphones can be read in the article referenced in the list of sources.
Electret microphone CMA-4544PF-W
The module contains electret microphone that requires a power supply of 3 to 10 volts. The correct polarity is important. Connect the module by a simple scheme: the conclusion "V" module to supply +3.3 or +5 volts, the output "G" of the module to GND of the Arduino, the output "S" to analog port "A0" of Arduino.
Connection diagram microphone to Arduino
Write a program for Arduino that will read the readings from microphone and output them to the serial port in the mV. Why might we need it? For example, to measure the level of noise; to control the robot to go for cotton or to stop. Some even manage to "teach" the Arduino to identify different sounds and thus create a more intelligent control: the robot will understand the commands "Stop" and "Go" (as, for example, in the article "voice Recognition using the Arduino" in the sources).
Sketch for the reading of electret microphone
Let's put a kind of equalizer according to the attached scheme.
A simple "equalizer" on Arduino
Some modifications to the sketch. Add LEDs and thresholds were triggered.
Equalizer is ready! Try to talk into the microphone and see how the LEDs light up when you change the volume of speech.
Sketch "equalizer"
Useful advice
The thresholds, after which light up corresponding LEDs depend on the set sensitivity of the microphone. I got 2000, 2125 and 2150 mV. You have to define them yourself.

Advice 2: What is an electret microphone

The principle of operation of electret microphones are similar to condenser principle of operation. The difference is that they do not require external power. The diaphragm of such microphones receives the electric charge in the process. For their food need only a small voltage (about 1.5 Volt), which is created using the installed microphone in the battery.
Electret microphone
Electret microphone is one of the types of condenser microphones. He used part of a set of electronic equipment for professional and household use, professional studios and Amateur conditions in recording and other devices. They are frequently used by radio Amateurs-hams. Electret microphone is very reliable, has low weight and flat frequency response (frequency response).

Device electret microphones

These MICS are made in the form of capacitors, a certain number of plates which are made from very thin plastic film located on the ring. The film is applied to the electron beam. It penetrates to a shallow depth, creates a spatial charge which has the ability to persist for a long time. These materials are called "electret", so the microphone is called an electret.

Then the film is overlaid with a very thin layer of metal that is used as one of the electrodes. The other electrode is a metal cylinder, a flat surface which is located next to the film. Its fluctuations created by acoustic waves, able to create between the electrodes an electric current. Due to the fact that the current in this case is very small and the output resistance reaches a large magnitude (gigamon), the transmission signal generated by the microphone is quite difficult.

For matching the low resistance of the amplifier and the high impedance of the microphone must use a special cascade, which is created on the field (unipolar) transistor. It is placed in the body of the MIC capsule (the so-called device, which is not only the microphone but also the matching cascade). The body should be metallic, having the ability to isolate the microphone and to negotiate the cascade, making protecting it from external fields of electricity.

In order to understand the suitability for connection to the microphone one or the other amplifier, only connect to the input socket of the device (multimer). If, as a result it will show the voltage of 2-3 Volts, this means that the amplifier is suitable to work with an electret microphone.

The principle of operation and design

According to the principle of electret microphones are the same as the capacitor but the DC voltage in them is ensured by the charge of the electret deposited on the membrane in the form of a thin layer. This charge may persist for a long time (30 years or more)

The work of electret microphones is based on the ability of certain materials which have high dielectric constant, to change their surface charge due to the impact of the sound wave. These microphones have very high impedance, resulting in a possibility of their connection to amplifiers with high input impedance. In its design the microphones are divided into several types, when an electret material in them is at the front position is on a flexible diaphragm and is mounted on the back plate.

Advice 3: How to connect a LCD display for Nokia 5110 for Arduino

Deal with connecting a LCD monochrome display with a resolution of 84х48 points from the Nokia 5110 to the Arduino.
LCD screen for Nokia 5110
You will need
  • - Arduino;
  • LCD display for Nokia 5110/3310;
  • - connecting wires.
Connect LCD from Nokia 5110 Arduino according to the diagram above.
Connection diagram of LCD screen Nokia 5110 for Arduino
To work with this LCD screen written a lot of libraries. I suggest to use this: (the downloading of the file
To install rotaryforum the file to the directory of Arduino IDE/libraries/.
The library supports the following features.
LCD5110(SCK, MOSI, DC, RST, CS); - the announcement LCD screen showing the matching Arduino pins;
InitLCD([contrast]); - initialization of the 5110 display with optional indication of the contrast (0 to 127), the default value is 70;
setContrast(contrast); sets the contrast (0 to 127);
enableSleep(); - puts the screen to sleep mode;
disableSleep(); - displays a screen from sleep mode;
clrScr(); - clears the screen;
clrRow(row, [start], [end]); - clear the selected line number of the row, from position start to end;
invert(true); invert(false); - disabling and enabling the inversion of the contents of the LCD screen;
print(string, x, y); - displays the character string with the specified coordinates; the x-coordinates you can use LEFT, CENTER and RIGHT; the height of the standard font is 8 points, so the line should go, with intervals of 8;
printNumI(num, x, y, [length], [filler]); - print the number on the screen at the given position (x, y); length - the desired length of the number; filler - the character to fill the "voids" if the number is less than the desired length; the default is an empty space " ";
printNumF(num, dec, x, y, [divider], [length], [filler]); - display a floating-point number; dec - number of decimal places divider - sign decimal separator, by default a period ".";
setFont(name); - choose the font; the built-in font called SmallFont and TinyFont; you can define your fonts in the sketch;
invertText(true); invertText(false); - invert text on/;
drawBitmap(x, y, data, sx, sy); - bring a picture to the screen coordinates x and y; data - an array containing the image; sx and sy are the width and height of the picture.
Write this sketch. First, attach the library, then declare an instance of the class LCD5110 with the terminal assignment.
In the procedure setup() initialize the LCD screen.
In the procedure loop() clear the screen and write in the small print arbitrary text underneath - medium font, display seconds counter.
The sketch to display text on the LCD screen Nokia 5110
Let's display picture. To do this, prepare a monochrome image that you want to display Nokia 5110. Remember that the screen resolution is 48 by 84 points, and the picture should be no more. On the page convert image to array of bits. Download the resulting file with the extension "*.c" and add it to the project via the menu: Sketch -> Add file... or just put the file in the sketch directory, and then restart the Arduino development environment IDE.
Add the image file to the Arduino project
Now we need the code to declare an array with the image data (in my code this line extern uint8_t mysymb[];) and then use the function drawBitmap() to display the image in the desired location on the screen.
Output to LCD Nokia 5110
Upload the sketch in Arduino. Now the text is replaced by the picture, and every time the counter increases its value.
Text and image on the LCD screen Nokia 5110
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