     int x=1;
     char timeBuffer[9];
 
+  // clear screen before writing new text
+  matrix.fillScreen({0,0,0});
+
   if (RTC.read(tm)) {
     Serial.print("Ok, Time = ");
     print2digits(tm.Hour);

      /* Draw Error Message to SmartMatrix */
      matrix.setFont(font3x5);
      sprintf(timeBuffer, "Stopped");
      matrix.drawString(x, MATRIX_HEIGHT/2, clockColor, "Stopped");
      matrix.swapBuffers();
    } else {
      Serial.println("DS1307 read error!  Please check the circuitry.");
      Serial.println();

      /* Draw Error Message to SmartMatrix */
      matrix.setFont(font3x5);
      matrix.drawString(x, MATRIX_HEIGHT/2, clockColor, "No Clock");
      matrix.swapBuffers();
    }
    delay(9000);
  }
  delay(1000);

    if (hour < 10)
        x = 4;
    matrix.setFont(gohufont11b);
    matrix.drawString(x, MATRIX_HEIGHT/2 - 6, clockColor, timeBuffer);
    matrix.swapBuffers();
  } else {
    if (RTC.chipPresent()) {
