Why are you only using the top 4 bits ?, the data sheet says 8 bit, so you are only sending high bit data, if your low bits are not tied either hi or low, then they could well oscillate and give you random characters. If you look at the character table to send the letter A you need to send hex 41, this has high and low bits. The controller is totaly different to the LCD controllers, so you cannot use the LCDOUT commands. Your best bet is to try 5v serial.