On Sat, 20 Sep 1997 22:16:16 +0200 Eric van Es writes: >N STEENKAMP [M.ING E&E] wrote: > > >Thank you! EXACTLY what I was looking for! >Thanks a million Niki! There are 2 types of 16x1 modules out there. One type has the HD44780 chip and an LCD driver chip. It uses x8 or x11 drive for a true 16-character by one line. The characters appear sequentially in RAM. The other type has only the HD44780 chip. The controller must be set for x16 drive, since it is logically an 8x2 display. The LCD panel is built so the 2 lines appear end to end rather than above each other. There is a gap in the RAM between the two sides of the display just like the gap in RAM between the two lines of a 2-line display. If you're only seeing the left 8 characters on the display it is likely the x16 type. There is no way to test with software what kind it is. Even without any commands from the PIC, the HD44780 will reset itself into x8 mode and clear the display RAM at power-on. So when the power is turned on and the LCD drive voltage sufficiently high (or low, since it is relative to Vdd), some or all of the characters should change to dim or dark blocks. THis is a pretty good test of the LCD module. If you can't get anything at all on the screen you may have one of the high-temperature modules which requires more than 5V of LCD drive. In that case the LCD drive pin needs to be pulled negative a few volts.