If you don't have a 20x4 (they're really only a few bucks more) you might want to leave out the word wrap and scrolling. Sometimes long words or missed spaces will result in only two words left on your display. Frankly, I don't think scrolling makes sense with only two lines. If you are planning on using a 16x2 you will want to make some changes. This version makes use of the 4 digit parallel method of driving the display. When the bottom line is filled, all lines will scroll up one row and new text will continue to appear at the bottom.

If a word extends beyond the 20 column line, it will drop down to the next line. The sketch includes funtions for word wrap and scrolling. This project is built around the 20x4 LCD display. The more dahs you send at the beginning the sooner it locks into solid copy. The software tracks the speed of the sender's dahs to make its adjustments. If you are not seeing solid copy, press the restart button on your Arduino.

The first few characters may come out wrong while it homes in on the speed.

Arduino cw decoder