FM_Brocaster/FM_Brocaster.ino

/*
ESP32 Frequency Modulation Broadcaster

Some code is from my old game project but now is almost dead.

Wei - 2026

You can do anything you want to this source code. BUT you MUST cite the original soruce of the code...
*/
#include <SPI.h>
#include <U8g2lib.h>
#include <Wire.h>
#include "KT0803.h"

KT0803L fm(&Wire);

// ======================= Display ======================= 
#define SCREEN_W 128
#define SCREEN_H 64

#define OLED_MOSI 23 // SDA
#define OLED_CLK  18 // SCK
#define OLED_DC   27
#define OLED_CS   5
#define OLED_RST  14 // RES

U8G2_SH1106_128X64_NONAME_F_4W_HW_SPI u8g2(
  U8G2_R0,
  OLED_CS,
  OLED_DC,
  OLED_RST
);

// ======================= Joystick Pins =======================
#define JOY_X  4
#define JOY_Y  13
#define JOY_SW 2

#define FM_SDA 21
#define FM_SCL 22

typedef struct CursorPos {
  int x;
  int y;
} CursorPos;

void setup() {
  // debug
  Serial.begin(115200);

  // Initialize display
  u8g2.begin();

  // fm module
  Wire.begin();
  Wire.setClock(100000);

  // scan i2c devices
  byte error, address;
  int nDevices;

  for(address = 1; address < 127; address++ ) {
    Wire.beginTransmission(address);
    error = Wire.endTransmission();
    if (error == 0) {
      Serial.print("I2C device found at address 0x");
      if (address<16) Serial.print("0");
      Serial.println(address,HEX);
      nDevices++;
    }
  }
  if (nDevices == 0) Serial.println("No I2C devices found\n");

  // Set font and en-able unicode support
  u8g2.enableUTF8Print();
  u8g2.setFont(u8g2_font_6x12_tf);

  u8g2.clearBuffer();

  // Joystick 
  pinMode(JOY_SW, INPUT_PULLUP);
  analogReadResolution(12);

  // Set center position of the joystick 
  Serial.println("Correcting joystick... (Don't touch joystick when processing...)");

  int rawX = analogRead(JOY_X);
  int rawY = analogRead(JOY_Y);
  int cx = 2048;
  int cy = 2048;

  Serial.println("Initialization Finished");
}

void printScreen(int x, int y, const char* text, bool clear_screen, bool send_buffer) {
  if (clear_screen) {
    u8g2.clearBuffer();
  }

  u8g2.setCursor(x, y);
  u8g2.print(text);

  if (send_buffer) {
    u8g2.sendBuffer();
  }
}

struct JoyStickStatus;

JoyStickStatus getJoyStickerStatus(int pin_x, int pin_y, int pin_sw);

struct JoyStickStatus {
  bool up;
  bool down;
  bool left;
  bool right;
  bool pressed;
};

JoyStickStatus getJoyStickerStatus(int pin_x, int pin_y, int pin_sw) {
  JoyStickStatus status = {0};

  int x = analogRead(pin_x);
  int y = analogRead(pin_y);
  bool pressed = (digitalRead(pin_sw) == LOW);

  if (x >= 1800 && y >= 3800) {
    Serial.println("down");
    status.down = true;

  }

  if (x >= 1800 && y <= 500) {
    Serial.println("up");
    status.up = true;
  }

  if (x <= 500 && y >= 1800) {
    Serial.println("left");
    status.left = true;
  }

  if (x >= 3800 && y >= 1800) {
    Serial.println("right");
    status.right = true;
  }

  status.pressed = pressed;

  char buffer[100];
  snprintf(buffer, sizeof(buffer), "X:%d , Y:%d, SW:%s", x, y, pressed ? "PRESSED" : "RELEASED");
  Serial.println(buffer);

  return status;
}

void getJoyStickerDebugInfo(int start_x, int start_y, int pin_x, int pin_y, int pin_sw, bool print_in_serial) {
  int x = analogRead(pin_x);
  int y = analogRead(pin_y);
  bool pressed = (digitalRead(pin_sw) == LOW);

  u8g2.setCursor(start_x, start_y);
  u8g2.print("X: ");
  u8g2.print(x);

  u8g2.setCursor(start_x, start_y + 12);
  u8g2.print("Y: ");
  u8g2.print(y);

  u8g2.setCursor(start_x, start_y + 24);
  u8g2.print("SW: ");
  u8g2.print(pressed ? "PRESSED" : "RELEASED");

  JoyStickStatus status = getJoyStickerStatus(JOY_X, JOY_Y, JOY_SW);

  u8g2.setCursor(start_x, start_y + 36);
  if (status.up) {
    u8g2.print("Direction: UP");
  } 
  else if (status.down) {
    u8g2.print("Direction: DOWN");
  }
  else if (status.left) {
    u8g2.print("Direction: LEFT");
  }
  else if (status.right) {
    u8g2.print("Direction: RIGHT");
  }

  if (print_in_serial) {
    char buffer[100];
    snprintf(buffer, sizeof(buffer), "X:%d , Y:%d, SW:%s", x, y, pressed ? "PRESSED" : "RELEASED");
    Serial.println(buffer);
  }
}

int selectOptionID = 1;
int currentOptionPage = 0; // 0: Home, 1: JoyStick Debug, 2: FM Broadcast
const int optionIDList[] = {1,2};
int buttonPressCount = 0;
bool wasPressed = false;
unsigned long buttonPressTime = 0;

float roundToOneDecimal(float num) {
    return (int)(num * 10 + 0.5) / 10.0;
}

void hanleQuitMenuEvent() {
  JoyStickStatus joyStatus = getJoyStickerStatus(JOY_X, JOY_Y, JOY_SW);

  if (joyStatus.pressed && !wasPressed) {
    // Start time record
    buttonPressTime = millis();
    wasPressed = true;
  }

  if (!joyStatus.pressed && wasPressed) {
    // Quit menu if pressed time more than over 3 sec
    unsigned long duration = millis() - buttonPressTime;

    if (duration >= 1500) {
      currentOptionPage=0;
    }

    wasPressed = false;
  }
}

void setFM(float freq, bool mute) {
  fm.setUSA();
  fm.setFrequency(freq);
  fm.setMute(mute);
}

void fmBroadcast(void) {
  float fm_freq = 98.1;
  float old_freq = 98.1;

  if (!fm.begin(fm_freq, false)) {
    Serial.println("FM Module KT0803 not found. Exiting...");
    printScreen(0, 14, "FM Module KT0803 not", true, false);
    u8g2.setCursor(0, 26);
    u8g2.print(" found. Exiting...");
    u8g2.sendBuffer();
    delay(3500);
    currentOptionPage=0;
    return;
  }

  setFM(fm_freq, false);

  while (currentOptionPage == 2) {
    int adc = analogRead(JOY_X);
    int offset = adc - 2048;

    if (abs(offset) > 200)
    {
        float speed = offset / 2048.0f;

        fm_freq += speed * 0.1f;
        fm_freq = roundToOneDecimal(fm_freq);

        // Max and min value check
        if (fm_freq < 88.0) {
          fm_freq = 88.0;
        }
        else if (fm_freq > 108.0) {
          fm_freq = 108.0;
        }
    }

    if (old_freq != fm_freq) {
      // Update frequency
      setFM(fm_freq, false);
      old_freq = fm_freq;
      Serial.print("Frequency: ");
      Serial.println(fm_freq);
    }

    printScreen(0, 14, "Brocasting_", true, false);
    u8g2.setCursor(0, 26);
    u8g2.print("Frequency: ");
    u8g2.print(fm.getFrequency());
    u8g2.setCursor(0, 38);
    u8g2.print("Now you can leave");
    u8g2.setCursor(0, 50);
    u8g2.print("this page.");
    u8g2.sendBuffer();
    delay(300);
    printScreen(0, 14, "Brocasting ", true, false);
    u8g2.setCursor(0, 26);
    u8g2.print("Frequency: ");
    u8g2.print(fm.getFrequency());
    u8g2.setCursor(0, 38);
    u8g2.print("Now you can leave");
    u8g2.setCursor(0, 50);
    u8g2.print("this page.");
    u8g2.sendBuffer();
    delay(300);
    hanleQuitMenuEvent();
  }
}

void joyStickDebugMenu(void) {
  while (currentOptionPage == 1) {
    printScreen(0, 14, "Debugging joystick.", true, false);
    getJoyStickerDebugInfo(0, 26, JOY_X, JOY_Y, JOY_SW, true);
    u8g2.sendBuffer();
    delay(300);
    printScreen(0, 14, "Debugging joystick..", true, false);
    getJoyStickerDebugInfo(0, 26, JOY_X, JOY_Y, JOY_SW, true);
    u8g2.sendBuffer();
    delay(300);
    printScreen(0, 14, "Debugging joystick...", true, false);
    getJoyStickerDebugInfo(0, 26, JOY_X, JOY_Y, JOY_SW, true);
    u8g2.sendBuffer();
    delay(300);
    printScreen(0, 14, "Debugging joystick....", true, false);
    getJoyStickerDebugInfo(0, 26, JOY_X, JOY_Y, JOY_SW, true);
    u8g2.sendBuffer();
    delay(300);
    hanleQuitMenuEvent();
  }
}

CursorPos printOptionMenu(int lastX, int lastY) {
  CursorPos pos = {lastX, lastY};
  
  pos.y+=12;
  u8g2.setCursor(pos.x, pos.y);
  u8g2.print("1: Debug Joystick");
  if (selectOptionID == 1) {
    u8g2.print(" [X]");
  } else {
    u8g2.print(" [ ]");
  }

  pos.y+=12;
  u8g2.setCursor(pos.x, pos.y);
  u8g2.print("2: FM Broadcast");
  if (selectOptionID == 2) {
    u8g2.print(" [X]");
  } else {
    u8g2.print(" [ ]");
  }
  return pos;
}

void handleOptionSelectEvent() {
  JoyStickStatus joyStatus = getJoyStickerStatus(JOY_X, JOY_Y, JOY_SW);
  size_t lengthOfOptions = sizeof(optionIDList) / sizeof(optionIDList[0]);

  if (joyStatus.down) {
    if (selectOptionID+1 <= lengthOfOptions) {
      selectOptionID+=1;
    }
  }
  else if (joyStatus.up) {
    if (selectOptionID-1 >= 1) {
      selectOptionID-=1;
    }
  }

  if (joyStatus.pressed) {
    buttonPressCount+=1;
  }

  // Do option page replace if button is pressed twice.
  if (buttonPressCount>=2) {
    buttonPressCount=0;
    currentOptionPage=selectOptionID;

    // Reset
    selectOptionID=1;
  }
}

void homeMenu(void) {
  while (currentOptionPage==0) {
    printScreen(0, 14, "Running_", true, false);
    CursorPos currentPos = printOptionMenu(0, 14);
    printScreen(currentPos.x, currentPos.y+24, "FM Brocaster v1.0", false, false);
    u8g2.sendBuffer();
    delay(300);

    // Handle option select event while the joystick is moving (?)
    handleOptionSelectEvent();

    printScreen(0, 14, "Running ", true, false);
    currentPos = printOptionMenu(0, 14);
    printScreen(currentPos.x, currentPos.y+24, "FM Brocaster v1.0", false, false);
    u8g2.sendBuffer();
    delay(300);
  }
}

void loop(void) {
  if (currentOptionPage == 0) {
    homeMenu();
  }
  else if (currentOptionPage == 1) {
    joyStickDebugMenu();
  }
  else if (currentOptionPage == 2) {
    fmBroadcast();
  }
}