Published May 4, 2023 © CC BY-NC-SA

Stereo Digital FM Transmitter Circuit (Arduino Code)

IntermediateFull instructions provided2 hours1,764

Story

Without a doubt, FM transmitter and Receiver are among the top favorite electronic project topics, however, building a digital FM transmitter can be a challenging project for electronics enthusiasts. The transmitter can then be connected to a source of audio, such as a phone or computer, to broadcast music or other audio content.

In this project, I have introduced a compact stereo digital FM transmitter circuit that operates in the frequency range of 87MHz to 108MHz. The frequency can be adjusted using two tactile push-buttons, with a 0.1MHz step size. The heart of the circuit is an ATMega8 microcontroller, which communicates with a 0.96-inch SPI OLED display and the KT0803L FM transmitter chip via an I2C interface. You can directly connect a microphone or an AUX cable to the board to broadcast your desired sound, such as playing a piece of music from your cellphone, computer, … etc. After conducting some tests, it was found that the circuit operates quite stable, and the received sound is clear and sharp.

To design the schematic and PCB, I used Altium Designer 23 and shared the project with my friends to get their feedback and updates using Altium-365. The fast component search engine (Octopart) allowed me to quickly consider components’ information and also generate the BOM. To get high-quality fabricated boards, I sent the Gerber files to PCBWay. I am confident that utilizing this circuit will be an enjoyable and fulfilling experience for you.

Full Article + PCB:https://www.pcbway.com/blog/technology/Stereo_Digital_FM_Transmitter_Circuit_64d799f3.html

Code

Code

#include <FMTX.h>
#include <SPI.h>
#include "SSD1306Ascii.h"
#include "SSD1306AsciiSpi.h"


#define CS_PIN 7
#define RST_PIN 9
#define DC_PIN 8
#define Down_Key 15
#define UP_Key 14


float frequency = 87.0;
float tolerance = 0.001;


SSD1306AsciiSpi oled;


void setup() {
  fmtx_init(frequency, EUROPE);
  oled.begin(&Adafruit128x64, CS_PIN, DC_PIN, RST_PIN);
  oled.setFont(Adafruit5x7);


  pinMode(Down_Key, INPUT);
  pinMode(UP_Key, INPUT);


  oled.clear();
  oled.set2X();
  oled.println("   FM-TR   ");
  oled.setRow(3);
  oled.setCol(40);
  oled.set2X();
  fmtx_set_freq(frequency);
  oled.println(frequency, 1);
}


void loop() {
  if (digitalRead(Down_Key) == 0 && frequency > 87.0) {
    delay(130);
    frequency = frequency - 0.1;
    fmtx_set_freq(frequency);
    if (frequency < 100.0) {
      oled.setRow(3);
      oled.println("           ");
      oled.setRow(3);
      oled.setCol(40);
      oled.println(frequency, 1);
    }
    if ((frequency - 100.0) >= -tolerance) {
      oled.setRow(3);
      oled.println("           ");
      oled.setRow(3);
      oled.setCol(35);
      oled.println(frequency, 1);
    }
  }
  if (digitalRead(UP_Key) == 0 && frequency < 108.0) {
    delay(130);
    frequency = frequency + 0.1;
    fmtx_set_freq(frequency);
    if (frequency < 100.0) {
      oled.setRow(3);
      oled.println("           ");
      oled.setRow(3);
      oled.setCol(40);
      oled.println(frequency, 1);
    }
    if ((frequency - 100.0) >= -tolerance) {
      oled.setRow(3);
      oled.println("           ");
      oled.setRow(3);
      oled.setCol(35);
      oled.println(frequency, 1);
    }
  }
}

Credits

Hesam Moshiri

51 projects • 32 followers

https://www.youtube.com/c/MyVanitar/videos

Stereo Digital FM Transmitter Circuit (Arduino Code)

Story

Schematics

PCB

Code

Code

Credits

Hesam Moshiri

Comments

Embed the widget on your own site

Stereo Digital FM Transmitter Circuit (Arduino Code)

Stereo Digital FM Transmitter Circuit (Arduino Code)

Story

Schematics

PCB

Code

Code

Credits

Hesam Moshiri

Comments

Related channels and tags