commit 3c1e42ac5300958eac45267312cb04f0dd4f5730
Author: wei <weidnite1222@gmail.com>
Date:   Fri Aug 28 23:16:37 2026 +0800

    Update files.

diff --git a/.gitignore b/.gitignore
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+.pio
diff --git a/include/KT0803/CHANGELOG.md b/include/KT0803/CHANGELOG.md
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+# Change Log KT0803
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](http://keepachangelog.com/)
+and this project adheres to [Semantic Versioning](http://semver.org/).
+
+
+## [0.3.1] - 2025-11-26
+- update GitHub actions
+- add derived classes KT0803L and KT0803M (wrappers for now)
+- update readme.md
+- minor edits
+
+## [0.3.0] - 2024-03-27
+- fix #5, getChannel()
+- fix KT0803K setChannel()
+- fix readData()
+- add several KT0803K specific functions (experimental)
+  - bool setMono()
+  - bool setStereo()
+  - bool isStereo()
+  - bool setBass(uint8_t bass)
+  - uint8_t getBass()
+  - bool powerOK()
+  - bool silenceDetected()
+- update GitHub actions
+- update readme.md
+- update keywords.txt
+- minor edits
+
+----
+
+## [0.2.0] - 2024-03-09
+- Fix #2 frequency to channel formula
+- add derived **class KT0803K**
+- add examples
+- add parameter checks functions.
+- add default frequency + mute to **begin()**
+- update documentation
+- update GitHub actions
+- minor edits
+
+----
+
+## [0.1.0] - 2023-12-27
+- initial version
diff --git a/include/KT0803/KT0803.cpp b/include/KT0803/KT0803.cpp
new file mode 100644
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--- /dev/null
+++ b/include/KT0803/KT0803.cpp
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+//
+//    FILE: KT0803.cpp
+//  AUTHOR: Rob Tillaart
+// VERSION: 0.3.1
+// PURPOSE: Arduino Library for KT0803 and KT0803K FM transmitter.
+//     URL: https://github.com/RobTillaart/KT0803
+
+
+#include "src/KT0803.h"
+
+
+//  REGISTERS on page 7 datasheet
+
+
+KT0803::KT0803(TwoWire * wire)
+{
+  _address  = 0x3E;
+  _wire = wire;
+}
+
+
+bool KT0803::begin(float freq, bool mute)
+{
+  if (! isConnected()) return false;
+  if (! setMute(mute)) return false;
+  return setFrequency(freq);
+}
+
+
+bool KT0803::isConnected()
+{
+  _wire->beginTransmission(_address);
+  return (_wire->endTransmission() == 0);
+}
+
+
+///////////////////////////////////////////////////////////
+//
+//  FREQUENCY
+//
+bool KT0803::setFrequency(float MHz)
+{
+  if ((MHz < 70) || (MHz > 108)) return false;
+  //  steps 50 KHz although KT0803 will truncate to 100 KHz.
+  return setChannel(round(MHz * 20));
+}
+
+
+//  MHz
+float KT0803::getFrequency()
+{
+  return getChannel() * 0.05;
+}
+
+
+//  steps of 50 KHz.
+bool KT0803::setChannel(uint16_t channel)
+{
+  if ((channel < 1400) || (channel > 2160)) return false;
+  //  need to split over 3 registers
+  //  register 2 part skipped (always 0) for KT0803
+  uint16_t ch = channel >> 1;
+
+  uint8_t register0 = ch & 0xFF;  //  CHSEL[8:1]
+  if (writeData(0x00, register0) == false) return false;
+
+  ch >>= 8;
+  uint8_t register1 = readData(0x01);
+  register1 &= 0xF8;         //  CHSEL[11:9]
+  register1 |= (ch & 0x07);  //  CHSEL[11:9]
+  return writeData(0x01, register1);
+}
+
+
+uint16_t KT0803::getChannel()
+{
+  uint16_t channel = readData(0x01) & 0x07;
+  channel <<= 8;
+  channel |= readData(0x00);
+  channel <<= 1;
+  return channel;
+}
+
+
+///////////////////////////////////////////////////////////
+//
+//  GAIN
+//
+bool KT0803::setPGA(uint8_t pga)
+{
+  if (pga > 7) return false;
+  uint8_t data = readData(0x01);
+  data &= 0xC7;   //  keep other bits
+  data |= (pga << 3);
+  return writeData(0x01, data);
+}
+
+
+uint8_t KT0803::getPGA()
+{
+  return (readData(0x01) >> 3) & 0x07;
+}
+
+
+bool KT0803::setRFGain(uint8_t rfgain)
+{
+  if (rfgain > 15) return false;
+  //  bits 0 and 1
+  uint8_t data = readData(0x01) & 0x3F;
+  data |= (rfgain & 0x03) << 6;
+  writeData(0x01, data);
+  // bit 2
+  data = readData(0x13) & 0x7F;
+  data |= (rfgain & 0x04) << 5;
+  writeData(0x13, data);
+  // bit 3
+  data = readData(0x02) & 0xBF;
+  data |= (rfgain & 0x08) << 3;
+  writeData(0x02, data);
+  return true;
+}
+
+
+uint8_t KT0803::getRFgain()
+{
+  uint8_t data = readData(0x01) >> 6;      //  bit 0, 1
+  data |= ((readData(0x13) & 0x80) >> 5);  //  bit 2
+  data |= ((readData(0x02) & 0x40) >> 3);  //  bit 3
+  return data;
+}
+
+
+bool KT0803::setPHTCNST(bool on)
+{
+  uint8_t data = readData(0x02);
+  //  is the bit already OK
+  if ((on == true)  && (data & 0x01) == 0x01) return true;
+  if ((on == false) && (data & 0x01) == 0x00) return true;
+  //  otherwise flip the bit
+  data = data ^ 0x01;
+  return writeData(0x02, data);
+}
+
+
+///////////////////////////////////////////////////////////
+//
+//  MISC
+//
+bool KT0803::getPHTCNST()
+{
+  return (readData(0x02) & 0x01) > 0;
+}
+
+
+bool KT0803::setPilotToneAdjust(uint8_t mode)
+{
+  if (mode > 1) return false;
+  uint8_t data = readData(0x02);
+  //  is the bit already OK
+  if ((mode == 1) && (data & 0x04) == 0x04) return true;
+  if ((mode == 0) && (data & 0x04) == 0x00) return true;
+  //  otherwise flip the bit
+  data = data ^ 0x04;
+  return writeData(0x02, data);
+}
+
+
+uint8_t KT0803::getPilotToneAdjust()
+{
+  return (readData(0x02) & 0x04) > 0;
+}
+
+
+///////////////////////////////////////////////////////////
+//
+//  MUTE
+//
+bool KT0803::setMute(bool mute)
+{
+  uint8_t data = readData(0x02);
+  //  is the bit already OK
+  if ((mute == true)  && (data & 0x08) == 0x08) return true;
+  if ((mute == false) && (data & 0x08) == 0x00) return true;
+  //  otherwise flip the bit
+  data = data ^ 0x08;
+  return writeData(0x02, data);
+}
+
+
+bool KT0803::getMute()
+{
+  return (readData(0x02) & 0x08) > 0;
+}
+
+
+///////////////////////////////////////////////////////////////////////
+//
+//  PROTECTED
+//
+bool KT0803::writeData(uint8_t reg, uint8_t data)
+{
+  _wire->beginTransmission(_address);
+  _wire->write(reg);
+  _wire->write(data);
+  return (_wire->endTransmission() == 0);
+}
+
+
+int KT0803::readData(uint8_t reg)
+{
+  _wire->beginTransmission(_address);
+  _wire->write(reg);
+  _wire->endTransmission(false);  //  explicit no STOP  fig 3 page 4
+
+  if (_wire->requestFrom(_address, (uint8_t) 1) == 1)
+  {
+    uint8_t data = _wire->read();
+    return data;
+  }
+  return -1;
+}
+
+
+/////////////////////////////////////////////////////////////////////////////
+//
+//  DERIVED CLASS KT0803K
+//
+KT0803K::KT0803K(TwoWire * wire) : KT0803(wire)
+{
+}
+
+
+bool KT0803K::setChannel(uint16_t channel)
+{
+  if ((channel < 1400) || (channel > 2160)) return false;
+  //  need to split over 3 registers
+  uint16_t ch = channel;
+
+  uint8_t register2 = readData(0x02) & 0x7F;
+  register2 |= (channel & 0x01) << 7;   //  CHSEL[0]
+  if (writeData(0x02, register2) == false) return false;
+  ch >>= 1;
+
+  uint8_t register0 = ch & 0xFF;  //  CHSEL[8:1]
+  if (writeData(0x00, register0) == false) return false;
+
+  ch >>= 8;
+  uint8_t register1 = readData(0x01);
+  register1 &= 0xF8;         //  CHSEL[11:9]
+  register1 |= (ch & 0x07);  //  CHSEL[11:9]
+  return writeData(0x01, register1);
+}
+
+
+uint16_t KT0803K::getChannel()
+{
+  uint16_t channel = readData(0x01) & 0x07;
+  channel <<= 8;
+  channel |= readData(0x00);
+  channel <<= 1;
+  channel |= (readData(0x02) >> 7);
+  return channel;
+}
+
+
+///////////////////////////////////////////////////////////
+//
+//  KT0803K SPECIFIC
+//
+bool KT0803K::setMono()
+{
+  uint8_t register4 = readData(0x04);
+  if (register4 & (1 << 6))
+  {
+    register4 &= ~(1 << 6);
+    return writeData(0x04, register4);
+  }
+  return true;
+}
+
+
+bool KT0803K::setStereo()
+{
+  uint8_t register4 = readData(0x04);
+  if ((register4 & (1 << 6)) == 0)
+  {
+    register4 |= (1 << 6);
+    return writeData(0x04, register4);
+  }
+  return true;
+}
+
+bool KT0803K::isStereo()
+{
+  uint8_t register4 = readData(0x04);
+  return (register4 & (1 << 6));
+}
+
+
+bool KT0803K::setBass(uint8_t bass)  //  0..3 = 0, 5, 11, 17 dB
+{
+  if (bass > 3) return false;
+  uint8_t register4 = readData(0x04);
+  register4 &= ~0x03;  //  mask off bits
+  register4 |= bass;
+  return writeData(0x04, register4);
+}
+
+
+uint8_t KT0803K::getBass()
+{
+  uint8_t register4 = readData(0x04);
+  return register4 & 0x03;
+}
+
+
+bool KT0803K::powerOK()
+{
+  uint8_t register0F = readData(0x0F);
+  return (register0F & (1 << 4)) > 0;
+}
+
+
+bool KT0803K::silenceDetected()
+{
+  uint8_t register0F = readData(0x0F);
+  return (register0F & (1 << 2)) > 0;
+}
+
+
+/////////////////////////////////////////////////////////////////////////////
+//
+//  DERIVED CLASS KT0803L
+//
+KT0803L::KT0803L(TwoWire * wire) : KT0803K(wire)
+{
+}
+
+
+/////////////////////////////////////////////////////////////////////////////
+//
+//  DERIVED CLASS KT0803M
+//
+KT0803M::KT0803M(TwoWire * wire) : KT0803K(wire)
+{
+}
+
+
+//  -- END OF FILE --
+
diff --git a/include/KT0803/KT0803.h b/include/KT0803/KT0803.h
new file mode 100644
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--- /dev/null
+++ b/include/KT0803/KT0803.h
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+#pragma once
+//
+//    FILE: KT0803.h
+//  AUTHOR: Rob Tillaart
+// VERSION: 0.3.1
+// PURPOSE: Arduino Library for KT0803 and KT0803K FM transmitter
+//     URL: https://github.com/RobTillaart/KT0803
+
+
+#include "Arduino.h"
+#include "Wire.h"
+
+
+#define KT0803_LIB_VERSION          (F("0.3.1"))
+
+
+class KT0803
+{
+public:
+  KT0803(TwoWire * wire = &Wire);
+
+  bool     begin(float freq = 90.0, bool mute = true);
+  bool     isConnected();
+
+
+  //  FM FREQUENCY (70-108)
+  //  KT0803 truncates to 0.1 MHz
+  //  KT0803K (L&M) truncates to 0.05 MHz
+  bool     setFrequency(float MHz);
+  float    getFrequency();
+
+
+  //  FM CHANNEL (1400-2160)
+  //  KT0803 only supports even channels
+  //  KT0803K (L&M) supports all channels
+  bool     setChannel(uint16_t channel);
+  uint16_t getChannel();
+
+
+  //  GAIN
+  bool     setPGA(uint8_t pga);  //  0-3 = 0..-12dB   4-7 = 0..12dB
+  // 111: 12dB
+  // 110: 8dB
+  // 101: 4dB
+  // 100: 0dB
+  // 000: 0dB
+  // 001: -4dB
+  // 010: -8dB
+  // 011: -12dB
+  uint8_t  getPGA();
+
+  bool     setRFGain(uint8_t rfgain);  //  0-15
+  uint8_t  getRFgain();
+
+
+  //  REGION SELECTION
+  //  first four are wrappers
+  void     setEurope()    { setPHTCNST(true); };
+  void     setAustralia() { setPHTCNST(true); };
+  void     setUSA()       { setPHTCNST(false); };
+  void     setJapan()     { setPHTCNST(false); };
+  bool     setPHTCNST(bool on);
+  bool     getPHTCNST();
+
+
+  //  PILOT TONE ADJUST (PLTADJ)
+  bool     setPilotToneAdjust(uint8_t mode);  //  HIGH = 1 LOW = 0
+  uint8_t  getPilotToneAdjust();
+
+
+  //  MUTE software
+  bool     setMute(bool mute);  //  true == muted
+  bool     getMute();           //  isMuted().
+
+
+  //  direct access to registers - debug / develop
+  //  to access not implemented functions.
+  bool     writeData(uint8_t reg, uint8_t data);
+  int      readData(uint8_t reg);
+
+protected:
+
+  uint8_t   _address = 0x3E;  //  fixed address for KT0803.
+  TwoWire * _wire = NULL;
+};
+
+
+/////////////////////////////////////////////////////////////////////////////
+//
+//  DERIVED CLASSES
+//
+class KT0803K : public KT0803
+{
+public:
+  KT0803K(TwoWire * wire = &Wire);
+
+  //  CHANNEL
+  bool     setChannel(uint16_t channel);
+  uint16_t getChannel();
+
+  //  KT0803K SPECIFIC
+  bool     setMono();
+  bool     setStereo();
+  bool     isStereo();
+
+  bool     setBass(uint8_t bass);  //  0..3 = 0, 5, 11, 17 dB
+  uint8_t  getBass();
+
+  bool     powerOK();
+  bool     silenceDetected();
+};
+
+
+class KT0803M : public KT0803K
+{
+public:
+  KT0803M(TwoWire * wire = &Wire);
+};
+
+
+class KT0803L : public KT0803K
+{
+public:
+  KT0803L(TwoWire * wire = &Wire);
+};
+
+
+//  -- END OF FILE --
+
diff --git a/include/KT0803/LICENSE b/include/KT0803/LICENSE
new file mode 100644
index 0000000..0117adb
--- /dev/null
+++ b/include/KT0803/LICENSE
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2023-2025 Rob Tillaart
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/include/KT0803/README.md b/include/KT0803/README.md
new file mode 100644
index 0000000..c757db5
--- /dev/null
+++ b/include/KT0803/README.md
@@ -0,0 +1,377 @@
+
+[![Arduino CI](https://github.com/RobTillaart/KT0803/workflows/Arduino%20CI/badge.svg)](https://github.com/marketplace/actions/arduino_ci)
+[![Arduino-lint](https://github.com/RobTillaart/KT0803/actions/workflows/arduino-lint.yml/badge.svg)](https://github.com/RobTillaart/KT0803/actions/workflows/arduino-lint.yml)
+[![JSON check](https://github.com/RobTillaart/KT0803/actions/workflows/jsoncheck.yml/badge.svg)](https://github.com/RobTillaart/KT0803/actions/workflows/jsoncheck.yml)
+[![GitHub issues](https://img.shields.io/github/issues/RobTillaart/KT0803.svg)](https://github.com/RobTillaart/KT0803/issues)
+
+[![License: MIT](https://img.shields.io/badge/license-MIT-green.svg)](https://github.com/RobTillaart/KT0803/blob/master/LICENSE)
+[![GitHub release](https://img.shields.io/github/release/RobTillaart/KT0803.svg?maxAge=3600)](https://github.com/RobTillaart/KT0803/releases)
+[![PlatformIO Registry](https://badges.registry.platformio.org/packages/robtillaart/library/KT0803.svg)](https://registry.platformio.org/libraries/robtillaart/KT0803)
+
+
+
+# KT0803
+
+Arduino Library for KT0803 and KT0803K FM transmitter.
+
+
+### Legal point of attention
+
+In different countries there are different laws with respect to using transmitting devices 
+and their range. 
+Please inform yourself of the local rules and laws if and how you may or may not use a 
+device like the KT0803 in your projects, either hobby, commercial or otherwise.
+
+
+## Description
+
+**Experimental**
+
+This experimental library allows basic control of the KT0803 and / or the KT0803K 
+FM transmitter device.
+It is primary written to understand the possibilities and the interface of the device.
+
+The library is not tested by me with hardware yet. See future below.
+However it is verified to work by others.
+
+There are newer, more capable, follow up devices like model K, L and M.
+From these only the KT0803K is supported as a derived class.
+The L and the M versions of the device will work with the KT0803K class too
+as their functionality is equal or exceeds the K version. 
+As far as investigated the L and M versions are backwards compatible.
+
+Version 0.3.0 implements a few KT0803K specific functions, see section below.
+These will work for L and M devices too.
+
+For ATTinyX5 series there exists the TinyKT0803 class which is derived from this one.
+It uses a different I2C implementation. See - https://github.com/RobTillaart/TinyKT0803
+
+
+### Hardware
+
+Read datasheet for details.
+
+**Warning**
+The KT0803 is an 3.3 Volt device and cannot be connected directly to 5V MCU's.
+
+
+```
+                   +----------+
+                   |  KT0803  |
+             GND --|  1   16  |-- PA_OUT  RF analog output
+   Crystal    XI --|  2   15  |-- GND
+   Crystal    XO --|  3   14  |-- SCL     I2C Clock
+   3.3V    IOVDD --|  4   13  |-- SCA     I2C Data
+             GND --|  5   12  |-- GND
+   in left   INL --|  6   11  |-- GND
+   in right  INR --|  7   10  |-- RSTB    Reset
+   enable     SW --|  8    9  |-- GND
+                   |          |
+                   +----------+
+```
+
+
+### Frequency range
+
+The frequency range stated on the front page of the datasheet ==> 70 MHz - 108 MHz.
+The frequency range stated in table 2 ==> 76 MHz - 108 MHz.
+So the datasheet is at least ambiguous on this point.
+
+Keep in mind that the frequency range allowed differs per country.
+The library does not provide this filtering, explicit responsibility of the user.
+
+
+### Differences
+
+The KT0803K device has far more options, which are not all implemented.
+There is one important, the resolution or step-size of the frequency.
+
+|  device   |  step-size  |  Notes  |
+|:---------:|:-----------:|:--------|
+|  KT0803   |  100 KHz    |  in code all math is done with 50 KHz
+|  KT0803K  |   50 KHz    |
+
+Backwards compatible.
+According to the datasheet code for the KT0803 should work for the KT0803K.
+Code with the KT0803K class will probably not work on a KT0803.
+
+
+### Transmit frequency
+
+The transmit frequency can be set with **setFrequency(MHz)** or by **setChannel(channel)**.
+Note that the channel and frequency math of the KT0803 and the KT0803K is aligned 
+in this library. This allows exchange of channel data between device types.
+
+Note that the KT0803 will internally round to use 100 KHz steps.
+
+Some examples:
+
+|  Frequency   |  Channel  |  Notes  |
+|:------------:|:---------:|:-------:|
+|   70.00 MHz  |   1400    |  channel = freq (Mhz) \* 20
+|   70.05 MHz  |   1401    |  freq = channel \* 0.05
+|   70.10 MHz  |   1402    |
+|   76.00 MHz  |   1520    |
+|   80.00 MHz  |   1600    |
+|   89.70 MHz  |   1794    |  default (see registers datasheet)
+|  100.00 MHz  |   2000    |
+|  101.30 MHz  |   2026    |
+|  105.70 MHz  |   2114    |
+|  108.00 MHz  |   2160    |
+
+
+### Related
+
+- https://github.com/RobTillaart/KT0803
+- https://github.com/RobTillaart/TinyKT0803
+- https://www.hackster.io/hesam-moshiri/stereo-digital-fm-transmitter-circuit-arduino-code-2dbd8d
+- https://www.hackster.io/hesam-moshiri/full-digital-fm-receiver-with-arduino-and-tea5767-52be37
+- https://www.hackerstore.nl/Artikel/388
+- https://en.wikipedia.org/wiki/FM_broadcasting
+
+
+## Interface KT0803
+
+```cpp
+#include "KT0803.h"
+```
+
+### Constructor
+
+- **KT0803(TwoWire \*wire = &Wire)** constructor, 
+optional Wire interface.
+- **KT0803K(TwoWire \*wire = &Wire)** constructor, 
+optional Wire interface.
+- **KT0803L(TwoWire \*wire = &Wire)** constructor, 
+optional Wire interface.
+- **KT0803M(TwoWire \*wire = &Wire)** constructor, 
+optional Wire interface.
+- **bool begin(float freq = 90.0, bool mute = true)** initializes the library.
+Furthermore it checks if the deviceAddress is available on the I2C bus.
+Default it sets the frequency to 90 MHz and **mutes the signal**.
+Returns true if deviceAddress is found on the bus, false otherwise.
+- **bool isConnected()** test to see if deviceAddress is found on the I2C-bus.
+
+
+### Frequency
+
+- **bool setFrequency(float MHz)** converts the frequency in MHz to 
+call **setChannel(channel)**. The value of channel is rounded off depending 
+on the resolution of the device.
+Returns false if MHz is out of range or **setChannel()** fails.
+- **float getFrequency()** returns the current frequency in MHz, can be slightly different
+from the set value due to rounding math mentioned above.
+The return value is derived from a call to **getChannel()**
+- **bool setChannel(uint16_t channel)** writes the channel to broadcast on to the device.
+This involves two or three writes to different device registers.
+- **uint16_t getChannel()** reads the selected channel from the device and 
+returns it.
+
+
+### PGA
+
+Read Datasheet.
+
+The KT0803K has a **PGA_LSB** (2 bits) setting, which allows setting the gain
+with single (1) dB steps. This is not yet implemented in the library.
+
+- **bool setPGA(uint8_t pga)** sets gain according to table below.
+Returns false if pga is out of range (0..7).
+- **uint8_t getPGA()** returns 0..7, default 0.
+
+
+|  PGA  |  gain   |  notes  |
+|:-----:|:-------:|:-------:|
+|  111  |  12dB   |
+|  110  |   8dB   |
+|  101  |   4dB   |
+|  100  |   0dB   |
+|  000  |   0dB   |  default 
+|  001  |  -4dB   |
+|  010  |  -8dB   |
+|  011  |  -12dB  |
+
+
+### RFGain
+
+Read Datasheet.
+
+Note: the RFGain value (4 bits) is distributed over three registers.
+PA_BIAS (register 0x05) is only supported in the KT0803K device.
+It is not yet supported in the library.
+
+- **bool setRFGain(uint8_t rfgain)** sets rfgain according to table below.
+Returns false if rfgain is out of range (0..15).
+- **uint8_t getRFgain()** returns 0..15, default 15.
+
+
+|  RFGAIN  |   RFout      |  PA_BIAS = 1 |  notes  |
+|:--------:|:------------:|:------------:|:-------:|
+|   0000   |   95.5 dBuV  |      -       |
+|   0001   |   96.5 dBuV  |      -       |
+|   0010   |   97.5 dBuV  |      -       |
+|   0011   |   98.2 dBuV  |      -       |
+|   0100   |   98.9 dBuV  |      -       |
+|   0101   |  100.0 dBuV  |      -       |
+|   0110   |  101.5 dBuV  |      -       |
+|   0111   |  102.8 dBuV  |      -       |
+|   1000   |  105.1 dBuV  |  107.2 dBuV  |
+|   1001   |  105.6 dBuV  |  108.0 dBuV  |
+|   1010   |  106.2 dBuV  |  108.7 dBuV  |
+|   1011   |  106.5 dBuV  |  109.5 dBuV  |
+|   1100   |  107.0 dBuV  |  110.3 dBuV  |
+|   1101   |  107.4 dBuV  |  111.0 dBuV  |
+|   1110   |  107.7 dBuV  |  111.7 dBuV  |
+|   1111   |  108.0 dBuV  |  112.5 dBuV  |  default
+
+
+### Region selection
+
+Read datasheet for details.
+
+Note that not all frequencies are allowed in all regions / countries!
+
+The first four are convenience wrappers for **setPHTCNST()**
+If some region is missing please let me know the details and I can add 
+a wrapper for it.
+
+- **void setEurope()**
+- **void setAustralia()**
+- **void setUSA()**
+- **void setJapan()**
+- **bool setPHTCNST(bool on)** See table below.
+- **bool getPHTCNST()** returns set value.
+
+|  PHTCNST  |  time   |  Region  |
+|:---------:|:-------:|:--------:|
+|    0      |  75 μs  |  USA, Japan, (default)
+|    1      |  50 μs  |  Europe, Australia
+
+
+### PilotToneAdjust
+
+Read datasheet.
+
+- **bool setPilotToneAdjust(uint8_t mode)**  HIGH = 1 LOW = 0
+- **uint8_t getPilotToneAdjust()**
+
+
+### Mute
+
+Default the device is not muted, but **begin()** will default mute it.
+See interface section above.
+
+- **bool setMute(bool mute)** enables or disables the transmitting
+by muting the signal.
+- **bool getMute()** returns the current state of muting.
+
+
+## Preference channels
+
+The device and library do not implement the persistant store of user 
+selectable preferences (frequencies or channels).
+This can be implemented by the user in EEPROM or another persistent medium.
+
+Think of a class that holds an array of channels and optional descriptions.
+A minimal hardcoded preset sketch is in the examples.
+
+
+## Derived classes
+
+Three derived classes are made:
+
+- KT0803K has some extended functions.
+- KT0803L is backwards compatible with KT0803K. 
+It has far more registers in use than the KT0803/KT0803K.
+For now it is a wrapper around KT0803K.
+- KT0803M is identical to the KT0803K (no new registers).
+
+
+## Interface KT0803K / KT0803L / KT0803M
+
+Added functions in 0.3.0 (not tested), check datasheet.
+
+### Mono Stereo
+
+- **bool setMono()** idem
+- **bool setStereo()** idem
+- **bool isStereo()** idem
+
+### Bass
+
+- **bool setBass(uint8_t bass);  //  0..3 = 0, 5, 11, 17 dB
+- **uint8_t getBass()** idem
+
+### Misc
+
+- **bool powerOK()** idem
+- **bool silenceDetected()** idem
+
+
+## Future
+
+#### Must
+
+- improve documentation
+- buy hardware
+- test and verify.
+
+
+#### Should
+
+- add examples for KT0803K specific functions.
+- investigate KT0803L
+- RESET pin as optional parameter in constructor?
+- SW pin (ON/OFF) as optional parameter in constructor?
+  - add functions for sw on/off, 
+  - what is impact on settings? 
+  - call begin () again? => default
+  - explain well doc.
+
+#### Could
+
+- improve error handling
+- unit tests possible?
+- extend settings upon request **bold** are interesting, see table
+
+|  device   |  setting      |  register       |  Notes  |
+|:---------:|:-------------:|:---------------:|:--------|
+|  KT0803   |  PA_CTRL      |  13, bit 2      |  **WARNING in datasheet**
+|           |               |                 |  Should it be added in API?
+|  KT0803K  |  PGA_LSB      |  04, bit 4+5    |  gain fine tuning -> see PGA_MOD
+|  KT0803K  |  FDEV         |  04, bit 2+3    |  Frequency deviation adjustment
+|  KT0803K  |  PDPA         |  0B, bit 5      |  Power Amplifier Power Down ?
+|  KT0803K  |  PA_BIAS      |  0E, bit 1      |  PA bias current enhancement.
+|  KT0803K  |  LMTLVL       |  10, bit 3+4    |  **Internal audio limiter level control**
+|  KT0803K  |  PGAMOD       |  10, bit 0      |  PGA mode selection  (use PGA_LSB/ not)
+|  KT0803K  |  SLNCDIS      |  12, bit 7      |  Silence detection disable
+|  KT0803K  |  SLNCTHL      |  12, bit 4+5+6  |  Silence detection low threshold
+|  KT0803K  |  SLNCTHH      |  12, bit 1+2+3  |  Silence detection high threshold
+|  KT0803K  |  SW_MOD       |  12, bit 0      |  **Switching channel mode selection**
+|  KT0803K  |  SLNCTIME     |  14, bit 5+6+7  |  silence detection time
+|  KT0803K  |  SLNCCNTHIGH  |  14, bit 2+3+4  |  silence detection count high
+|  KT0803K  |  SLNCCNTLOW   |  15, bit 0+1+2  |  silence detection count low
+
+
+#### Wont (for now)
+
+- investigate tea5767 FM receiver (Out of scope for this library).
+- investigate efficiency of register access.
+  - caching all (allowed) registers in **begin()**
+    -  3 bytes for KT0803
+    - 12 bytes for KT0803K
+  - cache frequency.
+  - only writing is needed. 
+- send binary data over FM?
+- preset frequency array in .h file (hardcoded)
+- enums for parameters - readability?
+
+
+## Support
+
+If you appreciate my libraries, you can support the development and maintenance.
+Improve the quality of the libraries by providing issues and Pull Requests, or
+donate through PayPal or GitHub sponsors.
+
+Thank you,
+
diff --git a/include/KT0803/examples/KT0803K_minimal/KT0803K_minimal.ino b/include/KT0803/examples/KT0803K_minimal/KT0803K_minimal.ino
new file mode 100644
index 0000000..073ae83
--- /dev/null
+++ b/include/KT0803/examples/KT0803K_minimal/KT0803K_minimal.ino
@@ -0,0 +1,38 @@
+//
+//    FILE: KT0803K_minimal.ino
+//  AUTHOR: Rob Tillaart
+// PURPOSE: minimal demo
+//     URL: https://github.com/RobTillaart/KT0803
+
+
+#include "Arduino.h"
+#include "Wire.h"
+#include "KT0803.h"
+
+
+KT0803K FM_SEND;
+
+
+void setup()
+{
+  Serial.begin(115200);
+  while(!Serial);
+  Serial.println();
+  Serial.println(__FILE__);
+  Serial.print("KT0803_LIB_VERSION: ");
+  Serial.println(KT0803_LIB_VERSION);
+  Serial.println();
+
+  Wire.begin();
+
+  FM_SEND.begin();
+  FM_SEND.setChannel(2000);  //  * 0.05 100.00 MHz
+  FM_SEND.setMute(false);
+}
+
+void loop()
+{
+}
+
+
+//  -- END OF FILE --
diff --git a/include/KT0803/examples/KT0803K_presets/KT0803K_presets.ino b/include/KT0803/examples/KT0803K_presets/KT0803K_presets.ino
new file mode 100644
index 0000000..95ec1e0
--- /dev/null
+++ b/include/KT0803/examples/KT0803K_presets/KT0803K_presets.ino
@@ -0,0 +1,55 @@
+//
+//    FILE: KT0803K_minimal.ino
+//  AUTHOR: Rob Tillaart
+// PURPOSE: minimal demo hardcoded presets
+//     URL: https://github.com/RobTillaart/KT0803
+
+
+#include "Arduino.h"
+#include "Wire.h"
+#include "KT0803.h"
+
+
+KT0803L FM_SEND;
+
+//  hardcoded presets adjust to your need.
+//  note: presets by channel would take half the memory
+float preset[10] =
+{
+  88.6, 91.3, 92.2, 96.0, 97.3,
+  98.8, 100.1, 100.3, 105.4, 107.6
+};
+
+
+void setup()
+{
+  Serial.begin(115200);
+  while(!Serial);
+  Serial.println();
+  Serial.println(__FILE__);
+  Serial.print("KT0803_LIB_VERSION: ");
+  Serial.println(KT0803_LIB_VERSION);
+  Serial.println();
+
+  Wire.begin();
+
+  FM_SEND.begin(preset[0], false);
+}
+
+
+void loop()
+{
+  if (Serial.available())
+  {
+    char c = Serial.read();
+
+    if (c == 'm') FM_SEND.setMute(false);
+    if (c == 'M') FM_SEND.setMute(true);
+    //  select preset  0..9
+    int  p = c - '0';  //  convert to digit
+    if ((0 <= p) && (p <= 9)) FM_SEND.setFrequency(preset[p]);
+  }
+}
+
+
+//  -- END OF FILE --
diff --git a/include/KT0803/examples/KT0803K_setFrequency/KT0803K_setFrequency.ino b/include/KT0803/examples/KT0803K_setFrequency/KT0803K_setFrequency.ino
new file mode 100644
index 0000000..27d615f
--- /dev/null
+++ b/include/KT0803/examples/KT0803K_setFrequency/KT0803K_setFrequency.ino
@@ -0,0 +1,44 @@
+//
+//    FILE: KT0803_setFrequency.ino
+//  AUTHOR: Rob Tillaart
+// PURPOSE: minimal demo
+//     URL: https://github.com/RobTillaart/KT0803
+
+
+#include "Arduino.h"
+#include "Wire.h"
+#include "KT0803.h"
+
+
+KT0803K FM_SEND;
+
+
+void setup()
+{
+  Serial.begin(115200);
+  while(!Serial);
+  Serial.println();
+  Serial.println(__FILE__);
+  Serial.print("KT0803_LIB_VERSION: ");
+  Serial.println(KT0803_LIB_VERSION);
+  Serial.println();
+
+  Wire.begin();
+
+  FM_SEND.begin();
+  FM_SEND.setFrequency(105.75);
+  FM_SEND.setMute(false);
+
+  Serial.print("Freq: ");
+  Serial.println(FM_SEND.getFrequency());
+  Serial.print("Channel: ");
+  Serial.println(FM_SEND.getChannel());
+}
+
+
+void loop()
+{
+}
+
+
+//  -- END OF FILE --
diff --git a/include/KT0803/examples/KT0803_minimal/KT0803_minimal.ino b/include/KT0803/examples/KT0803_minimal/KT0803_minimal.ino
new file mode 100644
index 0000000..15d9192
--- /dev/null
+++ b/include/KT0803/examples/KT0803_minimal/KT0803_minimal.ino
@@ -0,0 +1,38 @@
+//
+//    FILE: KT0803_minimal.ino
+//  AUTHOR: Rob Tillaart
+// PURPOSE: minimal demo
+//     URL: https://github.com/RobTillaart/KT0803
+
+
+#include "Arduino.h"
+#include "Wire.h"
+#include "KT0803.h"
+
+
+KT0803 FM_SEND;
+
+
+void setup()
+{
+  Serial.begin(115200);
+  while(!Serial);
+  Serial.println();
+  Serial.println(__FILE__);
+  Serial.print("KT0803_LIB_VERSION: ");
+  Serial.println(KT0803_LIB_VERSION);
+  Serial.println();
+
+  Wire.begin();
+
+  FM_SEND.begin();
+  FM_SEND.setChannel(2000);  // * 0.05 = 100.00 MHz
+  FM_SEND.setMute(false);
+}
+
+void loop()
+{
+}
+
+
+//  -- END OF FILE --
diff --git a/include/KT0803/examples/KT0803_setFrequency/KT0803_setFrequency.ino b/include/KT0803/examples/KT0803_setFrequency/KT0803_setFrequency.ino
new file mode 100644
index 0000000..4e224dd
--- /dev/null
+++ b/include/KT0803/examples/KT0803_setFrequency/KT0803_setFrequency.ino
@@ -0,0 +1,43 @@
+//
+//    FILE: KT0803_setFrequency.ino
+//  AUTHOR: Rob Tillaart
+// PURPOSE: minimal demo
+//     URL: https://github.com/RobTillaart/KT0803
+
+
+#include "Arduino.h"
+#include "Wire.h"
+#include "KT0803.h"
+
+
+KT0803 FM_SEND;
+
+
+void setup()
+{
+  Serial.begin(115200);
+  while(!Serial);
+  Serial.println();
+  Serial.println(__FILE__);
+  Serial.print("KT0803_LIB_VERSION: ");
+  Serial.println(KT0803_LIB_VERSION);
+  Serial.println();
+
+  Wire.begin();
+
+  FM_SEND.begin();
+  FM_SEND.setFrequency(105.75);
+  FM_SEND.setMute(false);
+
+  Serial.print("Freq: ");
+  Serial.println(FM_SEND.getFrequency());
+  Serial.print("Channel: ");
+  Serial.println(FM_SEND.getChannel());
+}
+
+void loop()
+{
+}
+
+
+//  -- END OF FILE --
diff --git a/include/KT0803/examples/KT0803_sweep_2_seconds/KT0803_sweep_2_seconds.ino b/include/KT0803/examples/KT0803_sweep_2_seconds/KT0803_sweep_2_seconds.ino
new file mode 100644
index 0000000..2349e6a
--- /dev/null
+++ b/include/KT0803/examples/KT0803_sweep_2_seconds/KT0803_sweep_2_seconds.ino
@@ -0,0 +1,42 @@
+//
+//    FILE: KT0803_sweep_2_seconds.ino
+//  AUTHOR: Rob Tillaart
+// PURPOSE: minimal demo
+//     URL: https://github.com/RobTillaart/KT0803
+
+
+#include "Arduino.h"
+#include "Wire.h"
+#include "KT0803.h"
+
+
+KT0803 FM_SEND;
+
+
+void setup()
+{
+  Serial.begin(115200);
+  while(!Serial);
+  Serial.println();
+  Serial.println(__FILE__);
+  Serial.print("KT0803_LIB_VERSION: ");
+  Serial.println(KT0803_LIB_VERSION);
+  Serial.println();
+
+  Wire.begin();
+  FM_SEND.begin();
+  FM_SEND.setMute(false);
+}
+
+void loop()
+{
+  //  adjust to your local allowed frequencies
+  for (float freq = 88.0; freq <= 108.0; freq += 0.1)
+  {
+    FM_SEND.setFrequency(freq);
+    delay(2000);
+  }
+}
+
+
+//  -- END OF FILE --
diff --git a/include/KT0803/examples/KT0803_up_down/KT0803_up_down.ino b/include/KT0803/examples/KT0803_up_down/KT0803_up_down.ino
new file mode 100644
index 0000000..3480944
--- /dev/null
+++ b/include/KT0803/examples/KT0803_up_down/KT0803_up_down.ino
@@ -0,0 +1,75 @@
+//
+//    FILE: KT0803_up_down.ino
+//  AUTHOR: Rob Tillaart
+// PURPOSE: minimal demo
+//     URL: https://github.com/RobTillaart/KT0803
+
+
+#include "Arduino.h"
+#include "Wire.h"
+#include "KT0803.h"
+
+
+KT0803 FM_SEND;
+
+//  connect two buttons to GND
+//  adjust pins to your needs,
+uint8_t UP_PIN = 6;
+uint8_t DOWN_PIN = 7;
+float freq = 100.0;
+float newFreq = 100.0;
+
+
+void setup()
+{
+  Serial.begin(115200);
+  while(!Serial);
+  Serial.println();
+  Serial.println(__FILE__);
+  Serial.print("KT0803_LIB_VERSION: ");
+  Serial.println(KT0803_LIB_VERSION);
+  Serial.println();
+
+  pinMode(UP_PIN, INPUT_PULLUP);
+  pinMode(DOWN_PIN, INPUT_PULLUP);
+  Wire.begin();
+
+  FM_SEND.begin(freq, false);
+}
+
+
+void loop()
+{
+  //  adjust frequency with up and down button.
+  uint8_t u = digitalRead(UP_PIN);
+  uint8_t d = digitalRead(DOWN_PIN);
+  if ((u == 0) && (d == 0))
+  {
+    newFreq = 100.0;
+  }
+  else if (u == 0)
+  {
+    newFreq += 0.1;
+    if (newFreq > 108.0) newFreq = 108.0;
+  }
+  else if (d == 0)
+  {
+    newFreq -= 0.1;
+    if (newFreq < 88.0) newFreq = 88.0;
+  }
+  if (newFreq != freq)
+  {
+    freq = newFreq;
+    FM_SEND.setFrequency(freq);
+
+    Serial.print("Freq: ");
+    Serial.print(FM_SEND.getFrequency());
+    Serial.print("\t");
+    Serial.println(FM_SEND.getChannel());
+
+    delay(100);
+  }
+}
+
+
+//  -- END OF FILE --
diff --git a/include/KT0803/keywords.txt b/include/KT0803/keywords.txt
new file mode 100644
index 0000000..a9be2b9
--- /dev/null
+++ b/include/KT0803/keywords.txt
@@ -0,0 +1,55 @@
+# Syntax Colouring Map For KT0803
+
+
+# Data types (KEYWORD1)
+KT0803	KEYWORD1
+KT0803K	KEYWORD1
+KT0803L	KEYWORD1
+KT0803M	KEYWORD1
+
+
+# Methods and Functions (KEYWORD2)
+begin	KEYWORD2
+isConnected	KEYWORD2
+
+setFrequency	KEYWORD2
+getFrequency	KEYWORD2
+setChannel	KEYWORD2
+getChannel	KEYWORD2
+
+setPGA	KEYWORD2
+getPGA	KEYWORD2
+
+setRFGain	KEYWORD2
+getRFgain	KEYWORD2
+
+setEurope	KEYWORD2
+setAustralia	KEYWORD2
+setUSA	KEYWORD2
+setJapan	KEYWORD2
+setPHTCNST	KEYWORD2
+getPHTCNST	KEYWORD2
+
+setPilotToneAdjust	KEYWORD2
+getPilotToneAdjust	KEYWORD2
+
+setMute	KEYWORD2
+getMute	KEYWORD2
+
+
+# KT0803K specific
+setMono	KEYWORD2
+setStereo	KEYWORD2
+isStereo	KEYWORD2
+
+setBass	KEYWORD2
+getBass	KEYWORD2
+
+powerOK	KEYWORD2
+silenceDetected	KEYWORD2
+
+
+# Constants (LITERAL1)
+KT0803_LIB_VERSION	LITERAL1
+
+
diff --git a/include/KT0803/library.json b/include/KT0803/library.json
new file mode 100644
index 0000000..a90066c
--- /dev/null
+++ b/include/KT0803/library.json
@@ -0,0 +1,23 @@
+{
+  "name": "KT0803",
+  "keywords": "FM,Broadcast,KT0803K,KT0803L,KT0803M",
+  "description": "Arduino library for the KT0803 and KT0803K FM transmitter.",
+  "authors":
+  [
+    {
+      "name": "Rob Tillaart",
+      "email": "Rob.Tillaart@gmail.com",
+      "maintainer": true
+    }
+  ],
+  "repository":
+  {
+    "type": "git",
+    "url": "https://github.com/RobTillaart/KT0803.git"
+  },
+  "version": "0.3.1",
+  "license": "MIT",
+  "frameworks": "*",
+  "platforms": "*",
+  "headers": "KT0803.h"
+}
diff --git a/include/KT0803/library.properties b/include/KT0803/library.properties
new file mode 100644
index 0000000..65dd456
--- /dev/null
+++ b/include/KT0803/library.properties
@@ -0,0 +1,11 @@
+name=KT0803
+version=0.3.1
+author=Rob Tillaart <rob.tillaart@gmail.com>
+maintainer=Rob Tillaart <rob.tillaart@gmail.com>
+sentence=Arduino library for the KT0803 and KT0803K FM transmitter.
+paragraph=KT0803K, KT0803L, KT0803M
+category=Communication
+url=https://github.com/RobTillaart/KT0803
+architectures=*
+includes=KT0803.h
+depends=
diff --git a/include/README b/include/README
new file mode 100644
index 0000000..49819c0
--- /dev/null
+++ b/include/README
@@ -0,0 +1,37 @@
+
+This directory is intended for project header files.
+
+A header file is a file containing C declarations and macro definitions
+to be shared between several project source files. You request the use of a
+header file in your project source file (C, C++, etc) located in `src` folder
+by including it, with the C preprocessing directive `#include'.
+
+```src/main.c
+
+#include "header.h"
+
+int main (void)
+{
+ ...
+}
+```
+
+Including a header file produces the same results as copying the header file
+into each source file that needs it. Such copying would be time-consuming
+and error-prone. With a header file, the related declarations appear
+in only one place. If they need to be changed, they can be changed in one
+place, and programs that include the header file will automatically use the
+new version when next recompiled. The header file eliminates the labor of
+finding and changing all the copies as well as the risk that a failure to
+find one copy will result in inconsistencies within a program.
+
+In C, the convention is to give header files names that end with `.h'.
+
+Read more about using header files in official GCC documentation:
+
+* Include Syntax
+* Include Operation
+* Once-Only Headers
+* Computed Includes
+
+https://gcc.gnu.org/onlinedocs/cpp/Header-Files.html
diff --git a/lib/README b/lib/README
new file mode 100644
index 0000000..9379397
--- /dev/null
+++ b/lib/README
@@ -0,0 +1,46 @@
+
+This directory is intended for project specific (private) libraries.
+PlatformIO will compile them to static libraries and link into the executable file.
+
+The source code of each library should be placed in a separate directory
+("lib/your_library_name/[Code]").
+
+For example, see the structure of the following example libraries `Foo` and `Bar`:
+
+|--lib
+|  |
+|  |--Bar
+|  |  |--docs
+|  |  |--examples
+|  |  |--src
+|  |     |- Bar.c
+|  |     |- Bar.h
+|  |  |- library.json (optional. for custom build options, etc) https://docs.platformio.org/page/librarymanager/config.html
+|  |
+|  |--Foo
+|  |  |- Foo.c
+|  |  |- Foo.h
+|  |
+|  |- README --> THIS FILE
+|
+|- platformio.ini
+|--src
+   |- main.c
+
+Example contents of `src/main.c` using Foo and Bar:
+```
+#include <Foo.h>
+#include <Bar.h>
+
+int main (void)
+{
+  ...
+}
+
+```
+
+The PlatformIO Library Dependency Finder will find automatically dependent
+libraries by scanning project source files.
+
+More information about PlatformIO Library Dependency Finder
+- https://docs.platformio.org/page/librarymanager/ldf.html
diff --git a/platformio.ini b/platformio.ini
new file mode 100644
index 0000000..5e23c4f
--- /dev/null
+++ b/platformio.ini
@@ -0,0 +1,31 @@
+; PlatformIO Project Configuration File
+;
+;   Build options: build flags, source filter
+;   Upload options: custom upload port, speed and extra flags
+;   Library options: dependencies, extra library storages
+;   Advanced options: extra scripting
+;
+; Please visit documentation for the other options and examples
+; https://docs.platformio.org/page/projectconf.html
+
+[env:rymcu-esp32-s3-devkitc-1]
+platform = https://github.com/pioarduino/platform-espressif32/releases/download/53.03.11/platform-espressif32.zip
+board = rymcu-esp32-s3-devkitc-1
+framework = arduino
+board_build.flash_mode = dio
+monitor_speed = 115200
+lib_deps = 
+	olikraus/U8g2
+	RobTillaart/KT0803
+	https://github.com/pschatzmann/arduino-libhelix.git
+build_unflags = 
+	-std=gnu++11
+	-std=gnu++14
+	-std=gnu++17
+	-std=c++11
+	-std=c++14
+	-std=c++17
+build_flags = 
+	-std=gnu++20
+	-D CORE_DEBUG_LEVEL=0
+	-D BOARD_HAS_PSRAM
diff --git a/src/main.cpp b/src/main.cpp
new file mode 100644
index 0000000..3b62d36
--- /dev/null
+++ b/src/main.cpp
@@ -0,0 +1,970 @@
+/*
+AudioFMSynth
+This project only tested and working on ESP32 (Original) and ESP32-S3.
+If you would like to use this code to other board. It's necessary to ensue all PINs are able to use for this project.
+Some code may need to be rewritten to support the board.
+
+Some code is from my old game project, but now it is almost dead.
+
+Wei - 2026
+
+You can do anything you want to this source code. BUT you MUST cite the original source of the code.
+*/
+#include <SPI.h>
+#include <SD.h>
+#include <U8g2lib.h>
+#include <Wire.h>
+#include "KT0803.h"
+#include <ESP_I2S.h>
+#include "MP3DecoderHelix.h"
+
+#define VERSION "1.2"
+
+KT0803L fm(&Wire);
+
+// ======================= Display =======================
+#define SCREEN_W 128
+#define SCREEN_H 64
+
+// For esp32 (original)
+// #define OLED_MOSI 23 // SDA ESP32
+// #define OLED_CLK  18 // SCK
+// #define OLED_DC   27
+// #define OLED_CS   5
+// #define OLED_RST  14 // RES
+
+// esp32-s3
+#define OLED_MOSI 11 // SDA ESP32
+#define OLED_CLK  12 // SCK
+#define OLED_DC   16
+#define OLED_CS   14
+#define OLED_RST  17 // RES
+
+U8G2_SH1106_128X64_NONAME_F_4W_HW_SPI u8g2(
+  U8G2_R0,
+  OLED_CS,
+  OLED_DC,
+  OLED_RST
+);
+
+// ======================= Joystick Pins =======================
+// esp32 (original)
+// #define JOY_X  34
+// #define JOY_Y  35
+// #define JOY_SW 32
+
+// esp32-s3
+#define JOY_X     1
+#define JOY_Y     2
+#define JOY_SW    7
+
+// esp32 (original)
+// #define FM_SDA 21
+// #define FM_SCL 22
+
+// esp32-s3
+#define FM_SDA    8
+#define FM_SCL    9
+
+// ======================= SD (microSD) Card =======================
+// esp32 (original)
+// #define SD_MOSI   23 // sd reader shares the same spi pin with the display
+// #define SD_MISO   19
+// #define SD_SCK    18
+// #define SD_CS     33
+
+// esp32-s3
+#define SD_MOSI   11
+#define SD_MISO   13
+#define SD_SCK    12
+#define SD_CS     15
+
+// ======================= PCM5102A DAC =======================
+// esp32 (original)
+// #define I2S_BCLK  26
+// #define I2S_LRCK  25
+// #define I2S_DOUT  17
+
+// esp32-s3
+#define I2S_BCLK  4
+#define I2S_LRCK  5
+#define I2S_DOUT  6
+
+// ====================== Button(s) ==========================
+#define BUTTON_1 10
+
+using namespace libhelix;
+
+constexpr uint32_t SAMPLE_RATE = 44100;
+constexpr float TONE_FREQ = 440.0f;
+constexpr int MAX_MUSIC_FILES = 20;
+constexpr int MAX_FILENAME_LEN = 48;
+
+char musicFiles[MAX_MUSIC_FILES][MAX_FILENAME_LEN];
+int musicFileCount = 0;
+int selectedMusic = 0;
+
+File playingFile;
+bool musicPlaying = false;
+bool musicPaused = false;
+bool musicButtonWasPressed = false;
+uint32_t currentAudioRate = SAMPLE_RATE;
+
+// Audio
+int dacVolume = 12;
+
+// Option & Menu
+int selectOptionID = 1;
+int currentOptionPage = 0; // 0: Home, 1: JoyStick Debug, 2: FM Broadcast, 3: PCM5102 Debug
+const int optionIDList[] = {1,2,3,4,5};
+const char* menuNames[] = {
+  "Debug Joystick",
+  "FM Broadcaster",
+  "Debug PCM5102",
+  "Volume",
+  "Play Music"
+};
+int buttonPressCount = 0;
+bool wasPressed = false;
+unsigned long buttonPressTime = 0;
+
+I2SClass I2S;
+
+void mp3DataCallback(MP3FrameInfo &info, int16_t *pcm, size_t len, void*) {
+  if (!pcm || !len || info.nChans < 1) return;
+
+  if ((uint32_t)info.samprate != currentAudioRate) {
+    if (I2S.configureTX(info.samprate, I2S_DATA_BIT_WIDTH_16BIT, I2S_SLOT_MODE_STEREO))
+      currentAudioRate = info.samprate;
+  }
+
+  constexpr size_t CHUNK_SAMPLES = 256;
+  int16_t out[CHUNK_SAMPLES * 2];
+
+  if (info.nChans == 1) {
+    for (size_t pos = 0; pos < len;) {
+      size_t n = min((size_t)CHUNK_SAMPLES, len - pos);
+      for (size_t i = 0; i < n; i++) {
+        int32_t v = (int32_t)pcm[pos + i] * dacVolume / 255;
+        out[i * 2] = out[i * 2 + 1] = (int16_t)v;
+      }
+      I2S.write(
+          reinterpret_cast<const uint8_t*>(out),
+          n * 2 * sizeof(int16_t)
+      );
+      pos += n;
+    }
+  } else {
+    for (size_t pos = 0; pos < len;) {
+      size_t n = min((size_t)(CHUNK_SAMPLES * 2), len - pos);
+      for (size_t i = 0; i < n; i++)
+        out[i] = (int16_t)((int32_t)pcm[pos + i] * dacVolume / 255);
+      I2S.write(
+          reinterpret_cast<const uint8_t*>(out),
+          n * sizeof(int16_t)
+      );
+      pos += n;
+    }
+  }
+}
+
+MP3DecoderHelix mp3(mp3DataCallback);
+
+typedef struct CursorPos {
+  int x;
+  int y;
+} CursorPos;
+
+void stopMusic() {
+  if (playingFile) playingFile.close();
+  if (musicPlaying) mp3.end();
+  musicPlaying = false;
+}
+
+void pauseMusic() {
+  if (!musicPlaying) return;
+  musicPaused = true;
+}
+
+void resumeMusic() {
+  if (!musicPlaying) return;
+  musicPaused = false;
+}
+
+void feedMusicDecoder() {
+  if (!musicPlaying || !playingFile || musicPaused) return;
+
+  uint8_t input[1024];
+  if (const size_t n = playingFile.read(input, sizeof(input)); n > 0) {
+    mp3.write(input, n);
+  } else {
+    stopMusic();
+    Serial.println("Playback finished");
+  }
+}
+
+/* This function stores some task that needs to be run in the background */
+void moduleLoop() {
+  feedMusicDecoder();
+}
+
+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;
+
+// Change its value if your joystick's position is not same as you expected.
+bool swapJoyStickVertical = false;
+bool swapJoyStickHorizontal = false;
+
+JoyStickStatus getJoyStickerStatus(int pin_x, int pin_y, int pin_sw);
+
+struct JoyStickStatus {
+  bool up;
+  bool down;
+  bool left;
+  bool right;
+  bool pressed;
+};
+
+int readJoystickAxis(int pin) {
+    constexpr int SAMPLE_COUNT = 4;
+
+    int sum = 0;
+
+    for (int i = 0; i < SAMPLE_COUNT; i++) {
+        sum += analogRead(pin);
+    }
+
+    return sum / SAMPLE_COUNT;
+}
+
+JoyStickStatus getJoyStickerStatus(int pin_x, int pin_y, int pin_sw) {
+  JoyStickStatus status = {0};
+
+  constexpr int CENTER_LOW  = 1500;
+  constexpr int CENTER_HIGH = 2600;
+
+  int x = readJoystickAxis(pin_x);
+  int y = readJoystickAxis(pin_y);
+  bool pressed = (digitalRead(pin_sw) == LOW);
+
+  status.up = x >= CENTER_LOW && x <= CENTER_HIGH && y < 500;
+  status.down = x >= CENTER_LOW && x <= CENTER_HIGH && y > 3800;
+  status.left = y >= CENTER_LOW && y <= CENTER_HIGH && x < 500;
+  status.right = y >= CENTER_LOW && y <= CENTER_HIGH && x > 3800;
+
+  if (swapJoyStickVertical) {
+      // Wow, c++ have this cool thing
+      std::swap(status.up, status.down);
+  }
+
+  if (swapJoyStickHorizontal) {
+      std::swap(status.left, status.right);
+  }
+
+  status.pressed = pressed;
+  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 = readJoystickAxis(pin_x);
+  int y = readJoystickAxis(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);
+  }
+}
+
+float roundToOneDecimal(const float num) {
+    return (num * 10 + 0.5) / 10.0;
+}
+
+int handleQuitMenuEvent() {
+  const 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 the menu if pressed time more than over 1.5 sec
+    if (const unsigned long duration = millis() - buttonPressTime; duration >= 1000) {
+      currentOptionPage=0;
+    }
+
+    wasPressed = false;
+  }
+  return currentOptionPage;
+}
+
+void setFM(float freq, bool mute) {
+  fm.setUSA();
+  fm.setFrequency(freq);
+  fm.setMute(mute);
+}
+
+void fmBroadcast() {
+  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) {
+    const int adc = analogRead(JOY_X);
+
+    if (const int offset = adc - 2048; abs(offset) > 200)
+    {
+        const float speed = static_cast<float>(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);
+    currentOptionPage = handleQuitMenuEvent();
+  }
+}
+
+void joyStickDebugMenu() {
+  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);
+    currentOptionPage = handleQuitMenuEvent();
+  }
+}
+
+CursorPos printOptionMenu(int lastX, int lastY, int availableHeight, int textSize) {
+  CursorPos pos = {lastX, lastY};
+
+  constexpr int optionCount = std::size(menuNames);
+  const int maxDisplayOptionCount = availableHeight / textSize;
+
+  // Below code is for scrolling menu support
+  int startIndex = selectOptionID - maxDisplayOptionCount / 2;
+
+  // border check
+  if (startIndex < 0) {
+    startIndex = 0;
+  }
+
+  if (startIndex + maxDisplayOptionCount > optionCount) {
+    startIndex = optionCount - maxDisplayOptionCount;
+  }
+
+  if (startIndex < 0) {
+    startIndex = 0;
+  }
+
+  int endIndex = min(startIndex + maxDisplayOptionCount, optionCount);
+
+  for (int i = startIndex; i < endIndex; i++) {
+    pos.y += 12;
+    u8g2.setCursor(pos.x, pos.y);
+
+    // Content
+    u8g2.print(i+1);
+    u8g2.print(": ");
+    u8g2.print(menuNames[i]);
+
+    if (selectOptionID == i + 1) {
+      u8g2.print(" [X]");
+    } else {
+      u8g2.print(" [ ]");
+    }
+  }
+
+  return pos;
+}
+
+int handleOptionSelectEvent() {
+  const JoyStickStatus joyStatus = getJoyStickerStatus(JOY_X, JOY_Y, JOY_SW);
+  constexpr size_t lengthOfOptions = std::size(optionIDList);
+
+  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;
+  }
+
+  return currentOptionPage;
+}
+
+void printLogo(int x, int y) {
+  // Draw background
+  u8g2.setDrawColor(1);
+  u8g2.drawBox(x, y, 128 - x, 1);
+
+  // Draw text
+  u8g2.setCursor(x + 2, y + 10);
+
+  u8g2.print("AudioFMSynth v");
+  u8g2.print(VERSION);
+}
+
+void homeMenu() {
+  bool frameMoment = false;
+  unsigned long lastDisplayUpdate = millis();
+  unsigned long lastTickUpdate = millis();
+  unsigned long lastAnimateUpdate = millis();
+  unsigned long perFrameTime = 33;
+  unsigned long perTickTime = 500;
+  unsigned long perAnimateTime = 500;
+
+  while (currentOptionPage == 0) {
+    moduleLoop();
+    const unsigned long time = millis();
+    if (time - lastTickUpdate >= perTickTime) {
+      lastTickUpdate = millis();
+      currentOptionPage = handleOptionSelectEvent();
+    }
+
+    if (time - lastAnimateUpdate >= perAnimateTime) {
+      lastAnimateUpdate = millis();
+      frameMoment = !frameMoment;
+    }
+
+    if (time - lastDisplayUpdate >= perFrameTime) {
+      lastDisplayUpdate = millis();
+      u8g2.clearBuffer();
+      u8g2.setCursor(0, 14);
+
+      if (frameMoment) {
+        u8g2.print("Running_");
+      } else {
+        u8g2.print("Running ");
+      }
+
+      const auto
+      [x, y] = printOptionMenu(0, 14, 36, 12);
+      printLogo(x, y + 2);
+
+      u8g2.sendBuffer();
+    }
+
+    delay(1);
+  }
+}
+
+void test_pcm5102(float sineFreq, float squareFreq, float triangleFreq) {
+    static float sinePhase = 0.0f;
+    static float squarePhase = 0.0f;
+    static float trianglePhase = 0.0f;
+
+    constexpr size_t FRAMES = 256;
+
+    int16_t samples[FRAMES * 2];
+
+    const float sineStep     = TWO_PI * sineFreq / SAMPLE_RATE;
+    const float squareStep   = TWO_PI * squareFreq / SAMPLE_RATE;
+    const float triangleStep = TWO_PI * triangleFreq / SAMPLE_RATE;
+
+    for (size_t i = 0; i < FRAMES; i++) {
+        float sine = 0.0f;
+        float square = 0.0f;
+        float triangle = 0.0f;
+
+        if (sineFreq > 0.0f) {
+            sine = sinf(sinePhase) * 2500.0f;
+        }
+
+        if (squareFreq > 0.0f) {
+            square = (squarePhase < PI ? 1.0f : -1.0f) * 1000.0f;
+        }
+
+        if (triangleFreq > 0.0f) {
+            triangle = static_cast<float>(trianglePhase < PI ? (2.0f * trianglePhase / PI - 1.0f) : (3.0f - 2.0f * trianglePhase / PI))* 1000.0f;
+        }
+
+        float mixed = sine + square + triangle;
+
+        mixed = constrain(mixed, -32768.0f, 32767.0f);
+
+        const auto sample = static_cast<int16_t>(mixed);
+
+        samples[i * 2]     = sample;
+        samples[i * 2 + 1] = sample;
+
+        sinePhase += sineStep;
+        squarePhase += squareStep;
+        trianglePhase += triangleStep;
+
+        if (sinePhase >= TWO_PI)
+            sinePhase -= TWO_PI;
+
+        if (squarePhase >= TWO_PI)
+            squarePhase -= TWO_PI;
+
+        if (trianglePhase >= TWO_PI)
+            trianglePhase -= TWO_PI;
+    }
+
+    I2S.write(
+        reinterpret_cast<uint8_t *>(samples),
+        sizeof(samples)
+    );
+}
+
+void pcm5102DebugMenu() {
+  unsigned long lastDisplayUpdate = 0;
+  int frameMoment = 0;
+  float frequency = TONE_FREQ;
+  float squareFreq = 0.0f;
+  float triangleFreq = 0.0f;
+
+  while (currentOptionPage == 3) {
+    test_pcm5102(frequency, squareFreq, triangleFreq);
+
+    u8g2.clearBuffer();
+    u8g2.setCursor(0, 14);
+
+    const int adc = readJoystickAxis(JOY_X);
+    int offset = adc - 2048;
+
+    if (abs(offset) > 200)
+    {
+        const float speed = static_cast<float>(offset) / 2048.0f;
+
+        frequency += speed * 0.1f;
+        frequency = roundToOneDecimal(frequency);
+    }
+
+    const int adcY = readJoystickAxis(JOY_Y);
+    offset = adcY - 2048;
+
+    if (offset > 0) {
+      // For triangle
+      offset = abs(offset);
+
+      const float speed = static_cast<float>(offset) / 2048.0f;
+      triangleFreq += speed * 0.1f;
+      triangleFreq = roundToOneDecimal(triangleFreq);
+    } else {
+      // For square
+      offset = abs(offset);
+
+      const float speed = static_cast<float>(offset) / 2048.0f;
+      squareFreq += speed * 0.1f;
+      squareFreq = roundToOneDecimal(squareFreq);
+    }
+
+    if (millis() - lastDisplayUpdate >= 300) {
+      lastDisplayUpdate = millis();
+
+      u8g2.clearBuffer();
+      u8g2.setCursor(0, 14);
+
+      switch (frameMoment) {
+        case 0:
+          u8g2.print("Debugging PCM5102.");
+          break;
+
+        case 1:
+          u8g2.print("Debugging PCM5102..");
+          break;
+
+        case 2:
+          u8g2.print("Debugging PCM5102...");
+          break;
+
+        case 3:
+          u8g2.print("Debugging PCM5102....");
+          break;
+        default: ;
+      }
+
+      u8g2.setCursor(0, 28);
+      u8g2.print("Sine Freq: ");
+      u8g2.print(frequency);
+      u8g2.setCursor(0, 40);
+      u8g2.print("Square Freq: ");
+      u8g2.print(squareFreq);
+      u8g2.setCursor(0, 52);
+      u8g2.print("Triangle Freq: ");
+      u8g2.print(triangleFreq);
+
+      u8g2.sendBuffer();
+
+      frameMoment = (frameMoment + 1) % 4;
+
+      currentOptionPage = handleQuitMenuEvent();
+    }
+  }
+}
+
+void volumeMenu() {
+  static unsigned long lastVolumeUpdate = 0;
+  while (currentOptionPage == 4) {
+    if (millis() - lastVolumeUpdate >= 30) {
+        lastVolumeUpdate = millis();
+
+        const JoyStickStatus status = getJoyStickerStatus(JOY_X, JOY_Y, JOY_SW);
+        int offset=0;
+        if (status.left) {
+          offset = 1;
+        } else if (status.right){
+          offset = -1;
+        }
+
+        dacVolume += offset;
+
+        dacVolume = constrain(dacVolume, 0, 255);
+
+        const int barWidth = (dacVolume * 84) / 255;
+
+        u8g2.firstPage();
+        do {
+          u8g2.setCursor(0, 14);
+          u8g2.print("Volume");
+
+          u8g2.drawFrame(20, 30, 88, 12);
+          u8g2.drawBox(22, 32, barWidth, 8);
+        } while (u8g2.nextPage());
+
+        currentOptionPage = handleQuitMenuEvent();
+        delay(1);
+    }
+  }
+}
+
+void scanMusicFiles() {
+  musicFileCount = 0;
+  File dir = SD.open("/music");
+  if (!dir || !dir.isDirectory()) return;
+  while (musicFileCount < MAX_MUSIC_FILES) {
+    File file = dir.openNextFile();
+    if (!file) break;
+    if (!file.isDirectory()) {
+      const char* name = file.name();
+      if (const char* ext = strrchr(name, '.'); ext && !strcasecmp(ext, ".mp3")) {
+        strncpy(musicFiles[musicFileCount], name, MAX_FILENAME_LEN - 1);
+        musicFiles[musicFileCount++][MAX_FILENAME_LEN - 1] = '\0';
+      }
+    }
+    file.close();
+  }
+  dir.close();
+}
+
+void handleMusicSelect() {
+  int y = readJoystickAxis(JOY_Y);
+  if (musicFileCount == 0) return;
+  if (y < 500) { selectedMusic = (selectedMusic + musicFileCount - 1) % musicFileCount; delay(200); }
+  else if (y > 3800) { selectedMusic = (selectedMusic + 1) % musicFileCount; delay(200); }
+}
+
+void drawMusicMenu() {
+  u8g2.clearBuffer();
+  u8g2.setCursor(0, 10); u8g2.print("Music");
+  if (!musicFileCount) {
+    u8g2.setCursor(0, 30); u8g2.print("No MP3 files");
+  } else {
+    for (int row = -1; row <= 1; row++) {
+      int index = selectedMusic + row;
+      if (index < 0 || index >= musicFileCount) continue;
+      int y = 32 + row * 12;
+      if (index == selectedMusic) { u8g2.setCursor(0, y); u8g2.print('>'); }
+      const char* name = musicFiles[index];
+      if (!strncmp(name, "/music/", 7)) name += 7;
+      char shown[18];
+      strncpy(shown, name, 17); shown[17] = '\0';
+      u8g2.setCursor(10, y); u8g2.print(shown);
+    }
+  }
+  u8g2.sendBuffer();
+}
+
+bool startMusic(const int index) {
+  stopMusic();
+
+  char path[MAX_FILENAME_LEN + 8];
+  const char* name = musicFiles[index];
+  if (name[0] == '/') snprintf(path, sizeof(path), "%s", name);
+  else if (!strncmp(name, "music/", 6)) snprintf(path, sizeof(path), "/%s", name);
+  else snprintf(path, sizeof(path), "/music/%s", name);
+
+  playingFile = SD.open(path, FILE_READ);
+  if (!playingFile) {
+    Serial.print("Unable to open: ");
+    Serial.println(path);
+    return false;
+  }
+
+  Serial.print("Playing: ");
+  Serial.println(path);
+  mp3.begin();
+  musicPlaying = true;
+  return true;
+}
+
+void musicMenu() {
+  scanMusicFiles();
+  musicButtonWasPressed = digitalRead(BUTTON_1) == LOW;
+  int lastMusic = 0;
+
+  while (currentOptionPage == 5) {
+    if (!musicPlaying) handleMusicSelect();
+    drawMusicMenu();
+
+    const bool pressed = digitalRead(BUTTON_1) == LOW;
+    if (pressed && !musicButtonWasPressed && musicFileCount > 0) {
+      if (!musicPlaying || selectedMusic != lastMusic) {
+        // Handle new music play and music switch
+        if (const bool ok = startMusic(selectedMusic); ok) {
+          lastMusic = selectedMusic;
+          musicPaused = false;
+        }
+      } else {
+        // Handle music pause
+        musicPaused = !musicPaused;
+      }
+    }
+
+
+    musicButtonWasPressed = pressed;
+
+    feedMusicDecoder();
+
+    currentOptionPage = handleQuitMenuEvent();
+    delay(1);
+  }
+
+  // stopMusic();
+}
+
+void setup() {
+  // debug
+  Serial.begin(115200);
+
+  // version info
+  Serial.printf("AudioFMSynth v%s\n", VERSION);
+
+  // Initialize display
+  u8g2.begin();
+  u8g2.setContrast(255);
+
+  // fm module
+  Wire.begin();
+  Wire.setClock(100000);
+
+  // ram check
+  if (psramFound()) {
+    Serial.println("PSRAM found!");
+    Serial.printf("PSRAM size: %f MB\n", roundToOneDecimal(ESP.getPsramSize() / (1024 * 1024)));
+    Serial.printf("Free PSRAM: %f MB\n", roundToOneDecimal(ESP.getFreePsram() / (1024 * 1024)));
+    } else {
+    Serial.println("No PSRAM found. Is highly recommend to enable PSRAM if you will use MP3 Player.");
+  }
+
+  // scan i2c devices
+  int nDevices = 1;
+
+  for(byte address = 1; address < 127; address++ ) {
+    Wire.beginTransmission(address);
+    if (const byte error = Wire.endTransmission(); 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");
+
+  // Set font and enable Unicode support
+  u8g2.enableUTF8Print();
+  u8g2.setFont(u8g2_font_6x12_tf);
+
+  u8g2.clearBuffer();
+
+  // Joystick
+  pinMode(JOY_SW, INPUT_PULLUP);
+  pinMode(BUTTON_1, 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;
+
+  // pcm5102
+  I2S.setPins(I2S_BCLK, I2S_LRCK, I2S_DOUT, -1, -1);
+
+  if (!I2S.begin(
+        I2S_MODE_STD,
+        SAMPLE_RATE,
+        I2S_DATA_BIT_WIDTH_16BIT,
+        I2S_SLOT_MODE_STEREO
+  )) {
+    Serial.println("Unable to init PCM5102 PINs");
+  } else {
+    Serial.println("I2S for PCM5102 is initialized.");
+  }
+
+  // Init SPI bus for sd card reader
+  SPI.begin(SD_SCK, SD_MISO, SD_MOSI);
+
+  // sd card
+  if (!SD.begin(SD_CS, SPI)) {
+    Serial.println("Unable to init SD card module. Did the SD module is installed?");
+  } else {
+    Serial.println("Found SD card module.");
+
+    if (const uint8_t cardType = SD.cardType(); cardType == CARD_NONE) {
+      Serial.println("No SD card detected.");
+    } else {
+      Serial.printf("SD Card Size: %llu MB\n", SD.cardSize() / (1024ULL * 1024ULL));
+      scanMusicFiles();
+
+      for (int i = 0; i < musicFileCount; i++) {
+          Serial.println(musicFiles[i]);
+      }
+    }
+  }
+
+  Serial.println("Initialization Finished");
+}
+
+void loop() {
+  if (currentOptionPage == 0) {
+    homeMenu();
+  }
+  else if (currentOptionPage == 1) {
+    joyStickDebugMenu();
+  }
+  else if (currentOptionPage == 2) {
+    fmBroadcast();
+  }
+  else if (currentOptionPage == 3) {
+    pcm5102DebugMenu();
+  }
+  else if (currentOptionPage == 4) {
+    volumeMenu();
+  }
+  else if (currentOptionPage == 5) {
+    musicMenu();
+  }
+}
\ No newline at end of file