   myTympan.println(input_gain_dB); //print text to Serial port for debugging
   myTympan.print("Digital Gain (dB) = "); 
   myTympan.println(digital_gain_dB); //print text to Serial port for debugging
+void setButtonText(String btnId, String text) {
+  myTympan.println("TEXT=BTN:" + btnId + ":"+text);
 }
+
+}

  //Add first page to GUI
  page_h = myGUI.addPage("MyFirstPage");
      card_h = page_h->addCard("Change Loudness");
        #if 0
          card_h->addButton("-","K");   //assumes default ID and default width. 
          card_h->addButton("+","k");   //assumes default ID and default width
        #else
          card_h->addButton("-","K","minusButton",6);  //displayed string, command, button ID, button width (out of 12)
          card_h->addButton("+","k","plusButton",6);   //displayed string, command, button ID, button width (out of 12)
        #endif
        
  //add some pre-defined pages to the GUI
  myGUI.addPredefinedPage("serialMonitor");
  myGUI.addPredefinedPage("plot");
}



    case 'k':
      changeGain(3.0);
      printGainLevels();
      setButtonText("gainIndicator", String(digital_gain_dB));
      break;
    case 'K':
      changeGain(-3.0);
      printGainLevels();
      setButtonText("gainIndicator", String(digital_gain_dB));
      break;
  }
}
