Frustration with SF LCD + atmega8

Development Boards MicroMod
1

atmega8 + SF 16x2 RED/BLACK LCD + Peter Fluery’s library + avr gcc

Here is what I did so far:

  • Wired it up on PORTD (4 bit I/O mode)

  • Compiled Peter Fluery’s LCD library

  • Ran included test. Screen is black.

  • Triple checked wiring

  • Made startup delays longer

  • Checked fuses for default 1MHz

  • Ran included test. Screen is black.

  • Googled, read all the results and verifed that the basics were covered

  • Rechecked wiring

  • Wired on PORTC

  • Recompiled with updated port defines

  • Ran included test. Screen is black

  • Coded up LED blinker as sanity check on ports d & c, worked fine

  • Breathed deep, let out slowly over teeth and started at 1 again

I am now pretty frustrated and need a way to verify the LCD actually works before I continue. The atmega8 has no JTAG fuse (common sighted issue for port not working) so I also need a fresh reason why this isn’t working assuming the LCD is healthy.

This is the exact wiring only mapped to the pins of PC0-6 on PDIP atmega8:

http://homepage.hispeed.ch/peterfleury/ … d-4bit.gif

2

Pins 15 and 16 on the LCD should be connected for the backlight since the character display is inverted. Without the backlight you won’t see anything.

If you’re using a 3 pin pot, try disconnecting the 5v. I remember doing the same thing a few months ago and I believe that having the 5v connected caused me problems. (You don’t need it to be powered anyway, so overall it’s wasteful… just have a variable resistor between the contrast pin and ground).

3

Walter,

I am in the same situation now.

Try to get a 16x2 LCD to work with an ATmega8 it has a HD44780 controller.

the data sheet says pins 15 & 16 are NC

triple checked the wiring and used to different code examples but no luck

any help would be appreciated zzz_murph007@yahoo.com