pschatzmann · October 21, 2025 10:07 · Oct 21, 2025 · Oct 21, 2025 · Oct 21, 2025
diff --git a/rtttl.md b/rtttl.md
@@ -42,7 +42,7 @@ void setup(void) {
   Serial.println("started...");
 }
 
-// Arduino loop - copy sound to out
+// Arduino loop - play rtttl tune
 void loop() {
   rtttl.setTransposeOctaves(-2);
   rtttl.begin(info);

diff --git a/rtttl.md b/rtttl.md
@@ -12,7 +12,7 @@ The examples usually use a __very high pitch__, so I added the functionality to
 
 ## Example Arduino Sketch
 
-Here is a simple example that uses an AI Thinker AudioKit as output device and the Saxophone provided by STK.
+Here is a simple example that uses an AI Thinker AudioKit as output device and the Saxophone provided by STK. The pitch of the example is too high, so we transpose it down by 2 octaves!
 
 ```C++
 #include "AudioTools.h"

diff --git a/rtttl.md b/rtttl.md
@@ -0,0 +1,53 @@
+Yesterday I was ask to extend my [Arduino AudioTools library](https://github.com/pschatzmann/arduino-audio-tools) to support __RTTTL__. To be honest, I had no clue what this is, so I had to look it up: RTTTL stands for __Ring Tone Text Transfer Language__ and was developed by Nokia to transfer ringtones to cellphones.
+
+It basically descibes the notes and durations in simple text form. My library supports [different sound generators](https://pschatzmann.github.io/arduino-audio-tools/group__generator.html) and also provides the [frequencies of all notes](https://pschatzmann.github.io/arduino-audio-tools/classaudio__tools_1_1_musical_notes.html): so all I needed was to provide a parser for RTTTL and link it up with the existing functionality. 
+
+The new class is called [RTTTOutput](https://pschatzmann.github.io/arduino-audio-tools/classaudio__tools_1_1_r_t_t_t_l_output.html) and you just provide the __generator__ and __output device__ in the constructor and then you can play the audio by printing the RTTTS string.
+
+Apart from the simple sound generators, we can use the STKGenerator class which provides access to [all instruments](https://pschatzmann.github.io/arduino-stk/html/classstk_1_1Instrmnt.html) provided by the STK framework.
+
+You can find a big collections of ringtones on the internet. Here is the link to one [extensive example collection](https://microblocks.fun/mbtest/NokringTunes.txt).
+
+The examples usually use a __very high pitch__, so I added the functionality to transpose the played notes by +-n octaves.
+
+## Example Arduino Sketch
+
+Here is a simple example that uses an AI Thinker AudioKit as output device and the Saxophone provided by STK.
+
+```C++
+#include "AudioTools.h"
+#include "AudioTools/AudioLibs/AudioBoardStream.h"
+#include "AudioTools/AudioLibs/AudioSTK.h" // install https://github.com/pschatzmann/Arduino-STK
+
+AudioInfo info(44100, 2, 16);
+Saxofony instrument(440); // the stk clarinet instrument
+STKGenerator<Instrmnt, int16_t> generator(instrument);    // subclass of SoundGenerator
+AudioBoardStream out(AudioKitEs8388V1);
+RTTTLOutput<int16_t> rtttl(generator, out);
+
+// Arduino Setup
+void setup(void) {
+  // Open Serial
+  Serial.begin(115200);
+  AudioToolsLogger.begin(Serial, AudioToolsLogLevel::Info);
+
+  // start I2S
+  Serial.println("starting I2S...");
+  auto config = out.defaultConfig(TX_MODE);
+  config.copyFrom(info);
+  out.begin(config);
+
+  // Setup generator
+  generator.begin(info);
+  Serial.println("started...");
+}
+
+// Arduino loop - copy sound to out
+void loop() {
+  rtttl.setTransposeOctaves(-2);
+  rtttl.begin(info);
+  rtttl.print("ZoVrolij:d=4,o=5,b=125:8g,8c6,8c6,8c6,8c6,8g,8g,8p,8g,8a,8a,8p,8a,8e,8e,8p,8e,8f,8d,8f,8d,8a,8g,8p,8g,8c,8d,8e,8g,c6,8p,8g,8c6,8c6,8c6,8c6,8g,8g,8p,8g,8a,8a,8p,8a,8e,8e,8p,8e,8f,8d,8f,8d,8a,8g,8p,8g,8c,8d,8e,8g,c6,8p,8c6,8c#6,8c#6,8c#6,8c#6,8g#,8g#,8p,8g#,8a#,8a#,8a#,8a#,8f,8f,8p,8f,8d#,8f,8f#,8d#,8a#,8g#,8p,8g#,8c#,8d#,8f,8g#,c#6,8p,8g#,8c#6,8c#6,8c#6,8c#6,8g#,8g#");
+  delay(3000);
+}
+
+```
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