DFPlayer and Arduino

Posted by M. 4Gani under Electronici:

DFplayer  module is quite small and looks good for little project.

The module read only audios in MP3 and WAV formats and all audio files must be placed under /mp3 folder.
It’s required that files are named like 0001.mp3, 0002.mp3…..0255.mp3 (4 letters not 2 or 3 letters)
The file names can have any characters after 4 digits, such as 0001_oclock.mp3


DFPlayer Mini module and Speaker
SD card – 2GB ~ 32GB formatted with FAT or FAT32
MP3 / WAV – audio files
2 x 1kOhm resistors

How to connect the cheap DFPlayer mini module to an Arduino:

The DFPlayer mini has three modes in which mp3 files can be played.
1) The files are stored in the root directory of the SD card.
2) Files are stored in folders, numbered 01-99, with filenames 001-255.mp3
3) Up to 2999 files are stored in the directory “mp3” with four-digit filenames 0001.mp3-2999.mp3
The serial connection need 1K ohm resistor (3.3 volts vs. 5volts arduino)

Reading the DFRobotDFPlayerMini.h is very instructive and easy to read:

void playFolder(uint8_t folderNumber, uint8_t fileNumber);
void playLargeFolder(uint8_t folderNumber, uint16_t fileNumber);
void playMp3Folder(int fileNumber);


mp3_play (74); means play audio file 0074.mp3


Set up an IR Receiver on a Arduino

Posted by M. 4Gani under Electronici:

The IR signal is a series of IR light pulses which are modulate with a high frequency known as the carrier frequency.
The carrier frequency used by most transmitters is 38 kHz.
The IR receiver has a bandpass and filtered 38 kHz than demodulates the IR light signal, pre-amplifier and converts it to a binary signal.
Each button on the remote control generate a unique hexadecimal code.
This is the information that is modulated and sent over IR to the receiver.

Hardware requirements:

– Arduino board
– IR receiver. Such as the TSOP38238
– An IR remote such as you use for controlling your TV,

Connecting the IR receiver is very simple.
The IR Remote Receiver Electronic Brick has 3 pins. GND, VCC and Signal.

There are many different IR remote controls.
All of these may have different encoding methods and number of physical buttons, and different codes received when a button is pressed.

The best way to find the key codes for your remote control you can upload this code to your Arduino and open the serial monitor.

Below an example Software Sketches for a few common IR Remotes.
You press a key on your remote and the program print the hexadecimal code.

Decoding IR Data

#include "IRremote.h"
int receiver = 11;                   // pin 1 of IR receiver to Arduino digital pin 11

IRrecv irrecv(receiver);
decode_results results;

void setup() {
  Serial.println("IR Receiver Raw Data + Button Decode Test");
  irrecv.enableIRIn();               // Start the receiver

void loop() {
  if (irrecv.decode(&results)) {    // have we received an IR signal?
    Serial.println(results.value, HEX);
    irrecv.resume();                // receive the next value

void translateIR() {                // takes action based on IR code received
  switch(results.value) {
    case 0xFF20DF: case 0x202C23D: Serial.println(" 0ff"); break;
    case 0xFFB04F: case 0x20238C7: Serial.println(" v+"); break;
    case 0xFF906F: case 0x202A857: Serial.println(" v-"); break;
    case 0xFF48B7: case 0x202B04F: Serial.println(" ok"); break;
    case 0xFFA857: case 0x202F807: Serial.println(" FORWARD"); break;
    case 0xFF08F7: case 0x20208F7: Serial.println(" LEFT"); break;
    case 0xFFC837: case 0x2028877: Serial.println(" RIGHT"); break;
    case 0xFF10EF: case 0x20220DF: Serial.println(" 4"); break;
    case 0xFF38C7: case 0x202A05F: Serial.println(" 5"); break;
    case 0xFF5AA5: case 0x202609F: Serial.println(" 6"); break;
    case 0xFF30CF: case 0x202807F: Serial.println(" 1"); break;
    case 0xFF18E7: case 0x20240BF: Serial.println(" 2"); break;
    case 0xFF7A85: case 0x202C03F: Serial.println(" 3"); break;
    case 0xFF42BD: case 0x202E01F: Serial.println(" 7"); break;
    case 0xFF4AB5: case 0x20210EF: Serial.println(" 8"); break;
    case 0xFF52AD: case 0x202906F: Serial.println(" 9"); break;
    case 0xFFC23D: case 0x20200FF: Serial.println(" 0"); break;
    default:  Serial.println("-> other button  <-");


DS18B20 & LCD 128×64

Posted by M. 4Gani under Electronici:

Before I start, let’s of a quick review about the differences between DHT22 Temperature and Humidity sensor and DS18B20 Temperature sensor 1-Wire. (DHT22 vs. DS18B20)

سنسور دما دیجیتال DS18B20,  سنسور رطوبت و دما DHT22, دماسنج NTC


DHT22 vs. DS18B20 & NTC

DHT22 vs. DS18B20 & NTC

DHT22 is a digital temperature and humidity sensor.
DHT22 has a capacitive humidity  and a thermistor sensor and measures the surrounding air in one device.
The device only has a digital signal output (NOT any analog output).
The data can be read from the output every 2 seconds .
It comes in different technologies and forms.

DS18B20 Temperature Sensor

DS18B20 is 1-Wire interface Temperature sensor. This sensor has 3 pins and looks like a transistor.
The sensors only requires one port pin for communication and needs NO other external components to work.

Each individual device has its unique ID.
This ID consists of a 64-bit number (8 bytes). The microcontroller calls a unique ID and receive the carry data information in two bytes from the device.

All the other devices connected to the bus remain silent during their ID is not called.
The sending the data bytes for a DS18B20 takes about 750 msec.

The thermometer resolution of DS18B20 is programmable from 9 to 12 bits and it converts 12-bit temperature to digital in less than 750 ms.

For my project I decided to use a DS18B20 Sensor.


– Arduino board
– DS18B20 Temperature Sensor module
– LCD 128×64 (ST7920) with serial mode – SPI



Clock with LCD 1602 & DS1307

Posted by M. 4Gani under Electronici:

Make a clock with DS1307 real clock module and 1602 16×2 LCD panel with back-panel to convert it to I2C protocol. (I2C راه اندازی با)
The time and date will be displayed in alphanumeric on LCD.

Clock with LCD 1602 16x2 & DS1307 real clock

Clock with LCD 1602 16×2 & DS1307

Device: LCD 1602 with back-panel  (نمایشگر LCD 16×2 کاراکتری دو سیمی)

The communication requires only two pins on the microcontroller bord: A4 and A5.
SDA: Analog 4
SCL: Analog5
GND: GND terminals
Contrast Adjust : has a built in potentiometer for contrast adjustment.
I2C Address: in my case is 0x27

You should see the LCD light up by starting, if it dose not happened, you may want to turn down the contrast of the LCD.

LCD has 2 lines, 16 character in each line and each character have 5-pixel in width and 8-pixel in height.
The LCD supports up to 8 custom characters numbered from 0 to 7.

The DS1307 Real time use also I2C Protocol to communicate with arduino.

Driver IC: I2C DS1307 Real Time Clock
Analog 5  (clock line)
SDA: Analog 4   (data line)
Voltage: 3.3V to 5V
GND:  GND of Arduino
I2C Address: in my case was 0x68

Each device on the I2C bus has its own unique address. The LCD display used here has address 0x27.
You can use the scanner script to find  I2C addresses on arduino by using

The I2C address used by a device can be found with the sketch i2c_scanner

I2C device found at address 0x27 !
I2C device found at address 0x68 !

To drive LCD I’m using the LiquidCrystal_I2C library, which seems to be commonly used.



DCF77 Signal with Arduino

Posted by M. 4Gani under Electronic, Ring Clock Projecti:

The DCF77 signal is a puls-signal with AM modulation with carrier frequency 77.5kHz. It has a small bandwidth.

The carries include time and date information and will be transmitted in a simple binary-coded format by on-off modulation of the carriers.  (100ms/200ms)
The Signal time and date code include the following information:

  • year, month, day of month, day of week
  • hour, minute, second, summer time

DCF receiver module with antenna (Radio Controlled Clock)

This module comes in different variants and forms and receive the 77.5 kHz signal from Frankfurt and decodes and sends the data stream to the output. The output signal can be processed by a microcontroller.

The normal inputs/outputs on a DCF receiver module are:

TCON = Digital output of carrier signal
PON (if provided) usually grounded to GND to enable the receiver.
Operating voltage from  +2.5V to +5.5V

The data input should be connected to a digital pin of arduino that uses  a interrupt!

Arduino only has two pins that are digital and each uses an interrupt.


Digital 2 with INT0/0

DCF77 Code

DCF77 Code

Digital 3 with INT0/1


Digital output of carrier signal has to connected to D2 pin OR D3 pin.

If the device dose not received clear signal, make sure the DCF-Antenne is enough away from the interfering source. (At least 2m)
For example:

– Monitor, Computer
– Fluorescent lamps
– Power supplies


The amplitude of the carrier is reduced every second to 25% (- 6db) in order to code “0/1” logic by the length of the amplitude (simple pulse width signal). A 100ms lowering is a logic “0” whereas 200ms is a logic”1″.

Every second is equal to one bit. The start of a new time sequence is signalized by the 59th second after which there is not lowering of the amplitude.
The week-day is coded as “1” for Monday and “7” for  Sunday.





 * DCFSignal.ino - DCF77 debug Example

#include <DCF77.h>
#include <Time.h>
using namespace Utils;
#define DCF_PIN 2         // Connection pin to DCF 77 device
#define DCF_INTERRUPT 0   // Interrupt number associated with pin
#define BLINK_PIN 13

time_t time;
void setup() {
  pinMode(DCF_PIN, INPUT);
  Serial.println("Waiting for DCF77 time ... ");
void loop() {
 time_t DCFtime = DCF.getTime(); // Check if new DCF77 time is available
 if (DCFtime!=0) {
    Serial.println("Time is updated");
void digitalClockDisplay(){
   Serial.print(" ");   Serial.print(day());
   Serial.print(" ");   Serial.print(month());
   Serial.print(" ");   Serial.print(year()); 
void printDigits(int digits){
  // utility function for digital clock display: prints preceding colon and leading 0
  if(digits < 10)



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